Putting speed control on attic fan
Mikepier
in my house caused by my attic fan. The motor I have on the fan is
similiar to this.
I wanted to get somekind of speed controller to slow down the speed of
the fan. I've seen them on Broan's website, and they are rated for 6
amps.
Any issues if I put the motor on a rheostat? Are these motors designed
to work on low voltage?
Ken
If you have negative air pressure in your attic, why don't you simply
add a few more vents? There are probably eaves where a vent could be
added reducing the pressure.
As far as controlling the speed of the fan motor, I think DC motors are
better suited for such control. Of course you could reduce the AC to an
AC motor, but it can present problems for the motor.
Mikepier
> Mikepier wrote:
> > A few weeks ago I posted a problem with too much negative air pressure
> > in my house caused by my attic fan. The motor I have on the fan is
> > similiar to this.
>
>
> > I wanted to get somekind of speed controller to slow down the speed of
> > the fan. I've seen them on Broan's website, and they are rated for 6
> > amps.
> > Any issues if I put the motor on a rheostat? Are these motors designed
> > to work on low voltage?
>
> If you have negative air pressure in your attic, why don't you simply
> add a few more vents? There are probably eaves where a vent could be
> added reducing the pressure.
>
> As far as controlling the speed of the fan motor, I think DC motors are
> better suited for such control. Of course you could reduce the AC to an
> AC motor, but it can present problems for the motor.
That's the problem, I think I have adequate vents. I have 2 roof
vents, and a gable vent. I'm not sure if adding another vent would fix
it.
beecrofter
> A few weeks ago I posted a problem with too much negative air pressure
> in my house caused by my attic fan. The motor I have on the fan is
> similiar to this.
>
>
> I wanted to get somekind of speed controller to slow down the speed of
> the fan. I've seen them on Broan's website, and they are rated for 6
> amps.
> Any issues if I put the motor on a rheostat? Are these motors designed
> to work on low voltage?
Open a window.
beecrofter
down in a place out of sight is a scary proposition even when
thermally protected.
I am guessing the living area is air conditioned otherwise you would
just open access to the attic .
Finding a slower replacement motor might be a better option.
Jim Elbrecht
Without getting to that point, I'd say that the desirability of those
fans is that they move vast amounts of air. I wouldn't slow that
process down.
The problem is in the basement. I'd address it there. If
leaving a window open isn't an option, then a small vent bringing some
outside air in would cure it.
If you've got a furnace down there, it is even more important. *It*
will also benefit from an unrestricted amount of air for combustion.
Jim
Home Guy
> > A few weeks ago I posted a problem with too much negative air
> > pressure in my house caused by my attic fan.
>
> If you have negative air pressure in your attic, why don't you simply
> add a few more vents? There are probably eaves where a vent could be
> added reducing the pressure.
There's a couple things going on here.
Normally, an attic space is supposed to be sealed from the house and air
isin't supposed to move between the attic and interior house air space.
Now, sometimes people put a fan in the ceiling to pull air from the
house and push it into the attic, which is useful to pull cooler
exterior air into the house to cool it down in the evening when there
isin't enough of a breeze to accomplish that. The OP doesn't say where
the fan is placed. The picture he shows is typical of a roof-mounted
fan, but I suppose could also be a house exhaust fan.
So if this is a roof-mounted fan, then the house shouldn't experience a
negative air pressure, and any air infiltration into the attic should be
sealed. It's hard to imagine that there wouldn't be enough soffit or
gable-end venting to allow proper attic air flow and air balance.
If this is a house exhaust fan that's exhasting air into the attic, then
it's normal to expect a negative air pressure in the house if you don't
open any windows to allow proper air balance. The whole point of having
a house exhaust fan is that you must allow exterior (outside) air into
the house to balance the airflow.
> As far as controlling the speed of the fan motor, I think DC motors
> are better suited for such control. Of course you could reduce the
> AC to an AC motor, but it can present problems for the motor.
I have a ceiling fan that's connected to an ordinary wall-mounted dimmer
switch (mainly to dim the lights that are part of the fan unit) but the
dimmer does change the fan's RPM along with the brightness of the
lights.
The downside of having a speed-controlled AC motor is RF noise created
by the controller or dimmer that gets injected into your power lines and
can mess up AM radio and sometimes OTA tv reception.
The solution is not to put a speed controller on the fan motor. The
solution is to allow proper air balance.
Mk
"Mikepier" <mike...@optonline.net> wrote in message
news:689bed80-27fc-433f...@c29g2000yqd.googlegroups.com...
Are you talking too much negative pressure inside the thermal envelope? If
so, the problem is your thermal envelope isn't _tight_. Slowing down the
attic fan isn't the solution to fixing the envelope problem.
Mikepier
I don't have issues with my furnace since in the cold weather, the
attic fan is off anyway. Its my water heater I have issues with.
I have a pull-down attic stairs in the second floor hallway. I know
it's not 100% sealed, but for the most part its pretty tight.
Vic Smith
I already asked about this, but I'll try again.
You just put in the water heater, right?
You posted about venting, but I don't know what you did.
Did you change the venting?
Did you have a problem with the old water heater pilot?
If not, you should look at your venting.
I've got no idea how you let that water heater chase you up to the
attic.
--Vic
Home Guy
I really have to wonder how you know that you have a negative pressure
issue when the attic roof fan is running.
Unless you have a really small attic space, or you know that your doors
and windows and walls are really well sealed, I would think that most
homes are leaky enough so that a single roof-mounted attic fan can't
cause a negative air pressure situation inside the house.
Do you know if your kitchen (stove) or bathroom exhaust fans run
straight through to the outside? Or do they exhaust directly into the
attic? If they do (exhaust into the attic) then that's where your
connection is between the attic and household airspace is.
Do you have a whole-house (built-in) vacuum cleaner system?
What sort of HVAC system does your home have? Does it have a makeup air
intake or combustion air heat exchanger? Is it open or closed?
Gas water heater?
Fire place / wood stove?
Tony Hwang
Hmmm,
You think about only output side, think about input side of the air
movement. Law of physics. Often times even vent size is not adequate.
What kind of soffit do you have? Now you are not venting the attic, you
are venting the house.
Bob F
Obviously, from the symptoms described, you don't have enough vents, or your fan
is way too big. IIRC, the required venting is 3 square feet / 100 sq. feet of
attic space. Half of that should be high in the space, and half should be very
low, like soffit vents. Do you have that? If all your vents are high in the
attic, that does not work well. Screen and louvers in the vents reduce the
effective area for your calculations.
You could contact Broan with your specific fan model # and ask them what would
work to control its speed.
Home Guy
> Obviously, from the symptoms described, you don't have enough vents,
> or your fan is way too big.
>
> You could contact Broan with your specific fan model # and ask them
> what would work to control its speed.
Why are all of you (except MK) overlooking the fact that he should not
be drawing interior house air into his attic in the first place?!
Yes, most probably he needs more attic venting, probably lower down
towards the soffit (he doesn't even say that he has soffits). I'm
guessing he has no roof over-hang at all.
But a roof fan shouldn't be able to create a negative pressure in the
house. I'd like to know more about what observations or measurements
he's made that makes him think he does have a negative pressure caused
by the roof fan.
Encouraging him or giving him pointers about a fan speed controller is
stupid and is a bad tangent to follow here.
Mikepier
wrote:
>
> - Show quoted text -
I thought I answered this last time, but the water heater is vented
through an exterior brick chimney. Its not going through the attic at
all. And the water heater is right underneath the chimney vent, so
total length of ducting from the water heater to the chimney is maybe
1 - 1 1/2 feet
Tony Hwang
Hmm,
I don't think I saw an attic fan under speed control. Most are on
thermostat switch which turns fan on or off depending on the temp.
inside the attic.
Vic Smith
<mike...@optonline.net> wrote:
>On Aug 22, 10:29 am, Vic Smith <thismailautodele...@comcast.net>
>>
>> I already asked about this, but I'll try again.
>> You just put in the water heater, right?
>> You posted about venting, but I don't know what you did.
>> Did you change the venting?
>> Did you have a problem with the old water heater pilot?
>> If not, you should look at your venting.
>> I've got no idea how you let that water heater chase you up to the
>> attic.
>>
>
>I thought I answered this last time, but the water heater is vented
>through an exterior brick chimney. Its not going through the attic at
>all. And the water heater is right underneath the chimney vent, so
>total length of ducting from the water heater to the chimney is maybe
>1 - 1 1/2 feet
You don't say if you changed the HW vent, either location relative to
the furnace vent, or angle of entry into the chimney, or went to a
different size.
And whether you had the problem with the previous tank.
I'm no expert on venting HW tanks.
I've always left them as I found them.
But you were talking about changing the venting.
If you did, that's where I'd look, not the attic.
Besides blowing out the pilot, wrong flue draft is a safety issue.
--Vic
Joe
> A few weeks ago I posted a problem with too much negative air pressure
> in my house caused by my attic fan. The motor I have on the fan is
> similiar to this.
>
>
> I wanted to get somekind of speed controller to slow down the speed of
> the fan. I've seen them on Broan's website, and they are rated for 6
> amps.
> Any issues if I put the motor on a rheostat? Are these motors designed
> to work on low voltage?
Don't you have any soffit vents? Reread the book on attic venting and
follow the best practices and the problem should resolve itself.
Joie
Mk
You also may want to look into sizing of the flue, meaning the chimney is
_too_ big. It may have been ok for the previous WH, but not this one.
Here's an article, which explains it better. Around here, we are not
allowed to vent into a brick or masonry chimney.
http://www.totalhomeinspection.com/hints_chimneys.shtml
Mikepier
wrote:
>
> - Show quoted text -
Vic, the venting is the same, I changed nothing. It is a 3" rigid duct
(per water heater spec) that leaves the water heater on an upward
pitch and goes directly into the chimney. It is not tied into the
furnace vent, which is on a seperate duct run.
The water heater was installed in January. I first noticed problems
when I started using the attic fan in the summer. If I do a match test
by the draft hood with the attic fan on, the flame is blown out. After
I shut off the attic fan, the flame test is fine, no issues.
Mikepier
> I don't think I saw an attic fan under speed control. Most are on
> thermostat switch which turns fan on or off depending on the temp.
> inside the attic.
This is the one on Broan's website
Vic Smith
<mike...@optonline.net> wrote:
>
>Vic, the venting is the same, I changed nothing. It is a 3" rigid duct
>(per water heater spec) that leaves the water heater on an upward
>pitch and goes directly into the chimney. It is not tied into the
>furnace vent, which is on a seperate duct run.
>The water heater was installed in January. I first noticed problems
>when I started using the attic fan in the summer. If I do a match test
>by the draft hood with the attic fan on, the flame is blown out. After
>I shut off the attic fan, the flame test is fine, no issues.
Okay, just checking.
Now I'm stumped too.
--Vic
Bob F
Obviously, the attic fan is drawing air through the house, which it shouldn't.
Even adding an external intake vent near the water heater will unlikely solve
the problem as long as the leakage occurs. You need to seal all the leaks into
the attic, and add more low intake vents to the attic, or just remove the attic
fan.
If the attic fan is being used as a whole house fan, you need to open more
windows when you run it. If you are using air conditioning at the same time as
the attic fan, the leakage into the attic is just throwing cooling money away
through it.
Mikepier
> windows when you run it. If you are using air conditioning at the same time as
> the attic fan, the leakage into the attic is just throwing cooling money away
> through it.
In my situation however, I think the attic fan helps with the A/C on.
My house was originally installed with force hot air heat, with the
supply ducts low to the ground. Like many other people in my
neighborhood, I added on Central A/C using the existing ductwork.
Because the return vent is low on the floor along with the supply
vents, I think the attic fan "draws" that air upwards, making it feel
cooler. I could be wrong though.
Vic Smith
Mike, I read up a bit on drafts, and found your attic fan issue isn't
unique. But I didn't find any simple solutions.
Your old water heater had a horizontal diverter, which probably did a
better job of keeping downdraft from the pilot.
Dumps any downdraft away from the heater.
These were common pre-1992, if not the norm.
That explains why the flame didn't blow out before.
Besides that, newer water FVIR heaters might use a smaller pilot
flame.
I don't know if horizontal diverters meet code now, but if they do,
putting that back on solves your flame-out problem.
I see no reason they won't meet code, since the new diverters are no
better that I can see.
Shouldn't change heater operation at all since you keep the supplied
hood. Just dumps the downdraft elsewhere.
I found one place selling horizontal diverters on the net, but can't
find it now. Very little can be found about them.
I saw the one on the pic you posted and remembered I tossed a couple
of them when I put in the new style heaters, but everybody else who
knows about them must have died before the net got going.
Strange.
You should turn up the heat on the water heater to go on when the
attic fan is running to see how quickly a draft is established,
Just for kicks.
If you don't put a horizontal diverter back in, I'd check to see if a
chimney cap can improve draft. I don't know about that.
I'd do all that before messing with the attic fan.
You should have CO detectors if you don't already.
--Vic
Home Guy
> Obviously, the attic fan is drawing air through the house, which
> it shouldn't.
I've said that about 5 times now in this thread.
Home Guy
> In my situation however, I think the attic fan helps with the
> A/C on.
The attic fan will help increase the life of your shingles, and it will
probably lower by a few degrees the air temp of the upper layer or
strata of air near the ceiling under the attic. You don't say if this
is a 2-story with basement, single story, etc.
> Because the return vent is low on the floor along with the supply
> vents, I think the attic fan "draws" that air upwards, making it
> feel cooler. I could be wrong though.
You are wrong.
There is no way that you would be feeling the effects (air currents)
inside your house caused by the roof fan - unless you had a massive hole
(several square feet) somewhere in your ceiling leading to your attic
space.
Home Guy
> Mike, I read up a bit on drafts, and found your attic fan issue
> isn't unique. But I didn't find any simple solutions.
There is no way his house is so well sealed such that his roof fan is
pulling interior house air into the attic, causing a negative pressure
that can only be relieved through the water heater flue pipe.
His water heater exhaust is vented directly into his chimney. Does the
chimney pass through the attic?
Why isin't anyone telling him to install a water-header draft motor?
How do we know that his furnace fan isin't causing negative pressure
around the general area of the furnace / water heater, causing reverse
air flow through the water heater flue pipe?
Is the furnace air-handler properly sealed?
Are there any return air vents/ducts near the furnace that can be
closed?
Is the furnace filter clear, or clogged?
Does the furnace have a humidifier? Is the humidifier housing sealed,
or leaky?
Vic Smith
>Vic Smith wrote:
>
>> Mike, I read up a bit on drafts, and found your attic fan issue
>> isn't unique. But I didn't find any simple solutions.
>
>There is no way his house is so well sealed such that his roof fan is
>pulling interior house air into the attic, causing a negative pressure
>that can only be relieved through the water heater flue pipe.
>
You can plug water heater downdraft attic fan into google and find
other cases.
Probably only happens when the chimney draft is just marginal without
an established flow.
>His water heater exhaust is vented directly into his chimney. Does the
>chimney pass through the attic?
>
What do you mean by that?
>Why isin't anyone telling him to install a water-header draft motor?
>
I don't know if you can retrofit them. Seems you can't, but I might
be wrong. Got a link?
>How do we know that his furnace fan isin't causing negative pressure
>around the general area of the furnace / water heater, causing reverse
>air flow through the water heater flue pipe?
>
>Is the furnace air-handler properly sealed?
>
>Are there any return air vents/ducts near the furnace that can be
>closed?
>
>Is the furnace filter clear, or clogged?
>
>Does the furnace have a humidifier? Is the humidifier housing sealed,
>or leaky?
He never mentioned if his A/C was running, so that might be worth
looking into.
--Vic
Home Guy
> > There is no way his house is so well sealed such that his roof
> > fan is pulling interior house air into the attic, causing a
> > negative pressure that can only be relieved through the water
> > heater flue pipe.
> You can plug water heater downdraft attic fan into google and find
> other cases.
A lot of people say "attic fan" and the answers seem to indicate
"whole-house" fan.
I have to wonder if most of these situations that you're finding on
google search are really just whole-house fan and NOT roof fan.
> Probably only happens when the chimney draft is just marginal without
> an established flow.
I'm thinking it's the HVAC fan.
Anyone with a conventional furnace will have enough convection heat from
the furnace combustion exhaust to establish a flow up the chimney to
pull the water-heater combustion exhaust. That's why most codes don't
call for water heater draft motor when the water heater is vented into
the chimney with existing conventional furnace. When you have a high
efficiency furnace, I think most codes will call for water heater draft
motor.
In the summer when the furnace is not on, you might have more of a
problem with chimney convection.
If the furnace is near the water heater, in a small enclosed space, I
can tell you for sure that the HVAC fan will definately try to pull air
from the closest source if the air handler plenum or air filter housing
is not sealed or if there are return air intakes nearby. A clogged air
filter will make this worse.
> > His water heater exhaust is vented directly into his chimney.
> > Does the chimney pass through the attic?
>
> What do you mean by that?
Never mind. I was thinking that a leaky chimney might be the cause of
his problem, but in fact it would actually help. If his chimney does
pass through the attic (on it's way out and above the roof) then the
roof exhaust fan would only help pull air out of the chimney if there
was a "leak" in the chimney. That would create a negative pressure at
the water heater flue intake - not a postive pressure like he's claiming
to have.
> > Why isin't anyone telling him to install a water-header
> > draft motor?
>
> I don't know if you can retrofit them. Seems you can't,
> but I might be wrong. Got a link?
I don't see why it wouldn't be easy to get ahold of a draft motor and
stick it on top of the water heater and connect it's ducting in-line
with the water heater exhaust stack and the chimney flue stack. It's
just a matter of "plumbing". Why do you think it's more complicated
than that?
> > Is the furnace air-handler properly sealed?
>
> He never mentioned if his A/C was running, so that might be
> worth looking into.
Not just the A/C, but is the HVAC fan running? (sometimes you just want
air circulation in the house, without the AC running)
gregz
> A few weeks ago I posted a problem with too much negative air pressure
> in my house caused by my attic fan. The motor I have on the fan is
> similiar to this.
>
>
> I wanted to get somekind of speed controller to slow down the speed of
> the fan. I've seen them on Broan's website, and they are rated for 6
> amps.
> Any issues if I put the motor on a rheostat? Are these motors designed
> to work on low voltage?
I always call my whole house fan, an attic fan, because that's what it is,
in the attic.
I use a green plug to slow it down a bit.
Greg
Vic Smith
>
>A lot of people say "attic fan" and the answers seem to indicate
>"whole-house" fan.
>
You're probably right. I didn't look close at first.
But Mike has said his attic fan causes a downdraft, and said it's just
an attic fan.
Pretty clear from his description.
>>
>> I don't know if you can retrofit them. Seems you can't,
>> but I might be wrong. Got a link?
>
>I don't see why it wouldn't be easy to get ahold of a draft motor and
>stick it on top of the water heater and connect it's ducting in-line
>with the water heater exhaust stack and the chimney flue stack. It's
>just a matter of "plumbing". Why do you think it's more complicated
>than that?
>
You'd have to figure how to turn it on and off automatically.
Don't know if downdraft would still blow out his pilot.
Seems the horizonal diverter is the easiest path.
--Vic
Home Guy
> > A lot of people say "attic fan" and the answers seem to indicate
> > "whole-house" fan.
>
> You're probably right. I didn't look close at first.
> But Mike has said his attic fan causes a downdraft, and said
> it's just an attic fan.
> Pretty clear from his description.
Actually, no.
Mike said this in his second response:
> This is a roof mouted fan, not a whole -house fan.
> > It's just a matter of "plumbing". Why do you think it's more
> > complicated than that?
>
> You'd have to figure how to turn it on and off automatically.
http://www.electricmotorwarehouse.com/fasco/hot_water_heater_blower.htm
Well, they probably sell these things where-ever you can buy a gas water
heater (home despot around here at least).
I don't know how they're controlled when you've got a hot water heater
with a standing pilot. Maybe some sort of thermostatic switch that can
detect when the burners are turned on.
> Don't know if downdraft would still blow out his pilot.
?
These draft motors pull air up out of the flue - they don't
"down-draft". They up-draft.
> Seems the horizonal diverter is the easiest path.
He needs to put a piece of paper to cover the flue opening at the top of
the water heater and see if the paper is really being pushed down / away
from the flue opening. Or go on the roof and put a piece of paper or
cardboard over the stack opening and see if it gets sucked or pulled
down. If it is, then something in his house is pulling air down
through his chimney, and it's not his roof-mounted ventillation fan. A
kitchen or bathroom fan, or his furnace fan is doing it. Maybe he's got
a window-mounted fan (or A/C unit?) somewhere doing it.
Mikepier
> the water heater and see if the paper is really being pushed down / away
> from the flue opening. Or go on the roof and put a piece of paper or
> cardboard over the stack opening and see if it gets sucked or pulled
> down. If it is, then something in his house is pulling air down
> through his chimney, and it's not his roof-mounted ventillation fan. A
> kitchen or bathroom fan, or his furnace fan is doing it. Maybe he's got
> a window-mounted fan (or A/C unit?) somewhere doing it.
I have confirmed multiple times its my attic fan.
Also my Central air has no effect on the downdraft. If the A/C is on
and the attic fan is off, the draft is fine.
My water heater has a sealed chamber for the pilot, so I don't know if
it would blow out that easily.
tra...@optonline.net
You said that the water heater is on it's own chimney. What
is that flue size? If it's a large size flue, typically used with
an old furnace, it's likely that the flue is too large. That presents
a problem of another kind. If it's too large, the exhaust gas
will cool off on the way out and condense back into water.
Natural gas exhaust is acidic and over time, that condensate
eats away at the mortar joints, causing the chimney to fail.
With a furnace on the same chimney flue, that was not a
problem because the chimney could only get cold enough
in winter to cause this to happen and then the furnace is
also running. That prevents it from happening. But with
no furnace, you don't want a gas water heater venting into
a chimney that is too large, unless the entire chimney is
surrounded by heated living space.
The solution is to put in a chimney liner, which is easy
to do. Having a chimney that is too large also means that it
will not draft properly, which could also be part of the
problem here.
Home Guy
> I have confirmed multiple times its my attic fan.
You've never really stated what problem you have (or you think you have)
because of this so-called negative pressure.
The one thing you've said is this:
> If I do a match test by the draft hood with the attic fan on,
> the flame is blown out
Does your water heater have a standing pilot, or electronic pilot?
Did you do this match test when the main burners on the water heater
were on, or off?
> Also my Central air has no effect on the downdraft. If the A/C
> is on and the attic fan is off, the draft is fine.
What is the condition of your home's windows and doors?
Do you think you have an ultra-sealed house? A house that's so air
tight that the only place that negative pressure can be relieved is
through your water heater flue stack?
Is your furnace near your water heater? Does it have open or closed
combustion venting (ie - is it high efficiency?).
> My water heater has a sealed chamber for the pilot, so I
> don't know if it would blow out that easily.
You really can't have a sealed chamber because combustion air has to be
able to enter the pilot and burner area (from somewhere) or you'll get
no burning.
> Also my Central air has no effect on the downdraft. If the A/C
> is on and the attic fan is off, the draft is fine.
What happens when you have the attic fan turned on, and you open a
window (a high window - second floor if you have one - you haven't said
if this is a single story or 2 story home). What happens with this
match test if the attic fan is on and you have a window open?
If you have pull-down stairs to get into the attic, then that's a large
area to seal compared to just an access hatch.
But I still wouldn't expect an attic (roof) fan to significantly
depressurize an entire house, unless you have the following MAJOR
problems:
1) you have insufficient passive soffit or gable venting (you haven't
said if you have soffits or a roof overhang)
2) you have gaps in the ceiling that connects your household airspace
with the attic airspace (perhaps where interior walls meet the attic, in
closets, etc). Generally hard to see areas.
3) Where are interior fans (kitchen, bathroom) vented? Into the attic,
or through the attic directly to the outside?
You need to tell us more about 1, 2 and 3. If you're too disinterested,
motivated or lazy to come up with an answer to those questions, then you
are not really serious about fixing your home and making it right, and
all of our efforts here are wasted on you.
Home Guy
> The solution is to put in a chimney liner
What the fuck is wrong with you?
If he really does have a reverse airflow through his flue caused by his
roof fan, then a chimney liner is going to do fuck-all to help that
situation.
tra...@optonline.net
Excuse me, ignoramus, but first, if you look at that in context,
which you did not, the problem I was specifically referring
to the chimney liner solving is the case where the chimney
is too large for the water heater. That problem can exist
regardless of any backdrafting issue and it can lead to long
term damage and failure of the chimney.
And second, having the flue correctly sized to the appliance
helps create the correct draft. If the flue is sized correctly
the hot gas stays hot and rises. If you dump a smaller
exhaust load into a chimney that is too large, the natural
draft action does not occur. So, yes the chimney liner
can help with a water heater that is having problems
with the exhaust backdrafting.
So, have another beer, maybe you'll feel better. More
likely though, it will just result in more profanity.
tra...@optonline.net
> Mikepier wrote:
> > I have confirmed multiple times its my attic fan.
>
> You've never really stated what problem you have (or you think you have)
> because of this so-called negative pressure.
He did in the other thread that he referred to and I think
most of us here have read it. Let me help you out:
http://groups.google.com/group/alt.home.repair/browse_frm/thread/9f9b9220ffb7845e?hl=en#
>
> The one thing you've said is this:
>
> > If I do a match test by the draft hood with the attic fan on,
> > the flame is blown out
>
> Does your water heater have a standing pilot, or electronic pilot?
Matters not a wit.
More attitude, eh? Why is this guy's problem of such emotional
interest
to you?
Home Guy
> > If he really does have a reverse airflow through his flue caused
> > by his roof fan, then a chimney liner is going to do fuck-all to
> > help that situation.
>
> Excuse me, ignoramus, but first, if you look at that in context,
> which you did not, the problem I was specifically referring
> to the chimney liner solving is the case where the chimney
> is too large for the water heater.
You can't say that his chimney is too large unless you know if he lives
in a northern climate and if he has a high-efficiency furnace.
In a northern climate, you can have condensation inside the chimney if
there is not enough total combustion flow (furnace + water heater).
Normally for a regular furnace, it's putting out enough exhaust to keep
a good convective heat flow going and "help" the water heater flue stack
flow.
In the summer, there really isin't a problem with needed help from the
furnace (which you won't get anyways because the furnace doesn't run in
the summer). The water heater exhaust flow should have no problem
getting up and out the chimney in the summer. Now if you have a reverse
air-flow in the chimney, then nothing you can do to the chimney
(including using a liner) is going to help with that.
So unless you know what type of furnace he has, and just how cold it
gets where he lives, then you can't say that he *needs* a liner for his
water heater exhaust.
And like I said before, even in cold climates it's standard to have a
non-lined chimney and have furnace and water-heater exhaust run
passively up and out the chimney. It's only when you have a
high-efficiency furnace do you start to look at using a draft motor or a
liner to help the water-heater exhaust.
> And second, having the flue correctly sized to the appliance
> helps create the correct draft.
Fuck the draft, and the sizing. This isn't rocket science.
When you've got something creating a negative pressure in the house,
causing reverse air-flow through the water heater flue, then you put
down your books and graphs and tables and you fix the reverse air
problem.
> If the flue is sized correctly the hot gas stays hot and rises.
Again, you're completely disregarding the whole point that started this
thread.
This boob thinks that he's getting a breeze flowing into his water
heater exhast flue and blowing out a match that he holds against the
draft intake vent (presumably the gap between the water heater and the
flue intake above it).
None of your correctly-sized shit is going to make that breeze go away.
gregz
> A few weeks ago I posted a problem with too much negative air pressure
> in my house caused by my attic fan. The motor I have on the fan is
> similiar to this.
>
> http://www.amazon.com/gp/product/B001XD0X4Q/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000BKQGDE&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=123R2NTM0Q87VFEGEJM8
>
> I wanted to get somekind of speed controller to slow down the speed of
> the fan. I've seen them on Broan's website, and they are rated for 6
> amps.
> Any issues if I put the motor on a rheostat? Are these motors designed
> to work on low voltage?
I already told about my green plug, slows fan down 10-30% depending on
motor and load.
Grab the old incense stick and check all wall outlets, switches, pot
lights, etc. With Ac off also check all air vents. Most tend to have leaks
to the attic when mounted in walls.
While your at it, you can do a check of leaks in windows, doors, etc.
I use my fans to do an energy audit.
Greg
Mk
"Mikepier" <mike...@optonline.net> wrote in message
news:bca0617c-adc4-4f17...@p5g2000vbl.googlegroups.com...
>
> attic fan is off anyway. Its my water heater I have issues with.
>
> I have a pull-down attic stairs in the second floor hallway. I know
> it's not 100% sealed, but for the most part its pretty tight.
I hadn't read about your match test, b/4 I posted about the flue size. I
would suggest as I seen someone else suggest, open a window or two when
your attic fan is on. Then, do the match test at the flue hood of WH. If it
doesn't go out, you know you have a deficiency in your thermal envelope.
I would also do a match test with the attic fan running, away from the
exhaust hood, with windows closed. Think close to the wall where a _chase_
for the chimney would be.
Depending on the test with a window open, I would start thinking leakage
around light fixtures, electrical going into attic through top plates, the
pull down staircase for starters.
Mikepier
> Does your water heater have a standing pilot, or electronic pilot?
Standing pilot
> Did you do this match test when the main burners on the water heater
> were on, or off?
Both, and both times the flame was blown out with the attic fan on
> What is the condition of your home's windows and doors?
Fairly new
> Do you think you have an ultra-sealed house? A house that's so air
> tight that the only place that negative pressure can be relieved is
> through your water heater flue stack?
I honestly don't think my house is air-tite, but obviously the attic
fan is pulling the air somehow.
> Is your furnace near your water heater? Does it have open or closed
> combustion venting (ie - is it high efficiency?).
I don't believe it's high efficiency. It's a Trane XR80, the exhaust
goes out on its own 6" duct, which by the way when I do a flame test
on the furnace duct without the water heater or furnace running, the
flame gets blown out also.
> What happens when you have the attic fan turned on, and you open a
> window (a high window - second floor if you have one - you haven't said
> if this is a single story or 2 story home). What happens with this
> match test if the attic fan is on and you have a window open?
If I open a window or door, the backdraft problem goes away. Once I
close the door or window, it takes a couple of minutes for the
backdraft problem to appear again.
This is in a 2 story split house.
> But I still wouldn't expect an attic (roof) fan to significantly
> depressurize an entire house, unless you have the following MAJOR
> problems:
>
> 1) you have insufficient passive soffit or gable venting (you haven't
> said if you have soffits or a roof overhang)
I have vented soffits, but I mentioned I also have 2 roof vents and a
gable vent.
> 2) you have gaps in the ceiling that connects your household airspace
> with the attic airspace (perhaps where interior walls meet the attic, in
> closets, etc). Generally hard to see areas.
I can't really see anything unusual.
> 3) Where are interior fans (kitchen, bathroom) vented? Into the attic,
> or through the attic directly to the outside?
Through the attic to the outside , and they are sealed rigid duct.
> You need to tell us more about 1, 2 and 3. If you're too disinterested,
> motivated or lazy to come up with an answer to those questions, then you
> are not really serious about fixing your home and making it right, and
> all of our efforts here are wasted on you.
You've obviously misjudged me for someone else.
Vic Smith
wrote:
Probably getting around the basement sill plates, HVAC ducting and
piping, then up through the walls and into the attic.
In my house, circa 1959, none of that is sealed.
Haven't looked at the attic sills, but I'm sure they're not sealed
either.
I don't think they sell green plugs any more.
You have the right idea, but he should go after the basement overhead
first if wants to solve the attic fan induced downdraft in the water
heater vent.
Somebody wrote about a thermal switch between HW and attic fan and
that's a good solution too.
Personally, if the draft didn't take long to be established with the
attic fan running, I'd put the horizontal diverter back in.
This is what they look like, and Mike had one on his old heater.
http://www.standexadp.com/specs.php?spec=28
That would prevent pilot blow-out and overheating the top of the tank.
I never had a pilot blow out with these but have with the hood style
diverter.
I'm not sure about spillage, but just guess it would be less.
You also need a CO detector nearby to play it safe.
This isn't a new draft problem, just a new water heater and venting.
--Vic
Mikepier
wrote:
> On Tue, 23 Aug 2011 15:45:36 +0000 (UTC), gregz <ze...@comcast.net>
> wrote:
>
>
>
>
>
> >Mikepier <mikep...@optonline.net> wrote:
> >> A few weeks ago I posted a problem with too much negative air pressure
> >> in my house caused by my attic fan. The motor I have on the fan is
> >> similiar to this.
>
> That would prevent pilot blow-out and overheating the top of the tank.
> I never had a pilot blow out with these but have with the hood style
> diverter.
> I'm not sure about spillage, but just guess it would be less.
> You also need a CO detector nearby to play it safe.
> This isn't a new draft problem, just a new water heater and venting.
>
>
> - Show quoted text -
What exactly does that diverter do? It is open on the bottom, right?
Thats what I had on my old water heater. Plus whoever installed the
previous water heater eliminated the draft hood for some reason, and
just put the 3" duct directly on top of the exhaust outlet. Now I'm
wondering if they did this because of the backdraft problem.
tra...@optonline.net
Is there any path direct from the basement to the attic?
A chimney chase? Other chase? Unconnected extra
HVAC duct?
It would seem more likely that would be needed to
draw significant air from the basement to the attic than for it
to happen by going through the living space.
tra...@optonline.net
> "trad...@optonline.net" wrote:
> > > If he really does have a reverse airflow through his flue caused
> > > by his roof fan, then a chimney liner is going to do fuck-all to
> > > help that situation.
>
> > Excuse me, ignoramus, but first, if you look at that in context,
> > which you did not, the problem I was specifically referring
> > to the chimney liner solving is the case where the chimney
> > is too large for the water heater.
>
> You can't say that his chimney is too large unless you know if he lives
> in a northern climate and if he has a high-efficiency furnace.
That is why I never said that his chimney is too large.
I only stated that the chimney needs to be correctly
sized to the appliance, in this case a water heater.
>
> In a northern climate, you can have condensation inside the chimney if
> there is not enough total combustion flow (furnace + water heater).
> Normally for a regular furnace, it's putting out enough exhaust to keep
> a good convective heat flow going and "help" the water heater flue stack
> flow.
>
> In the summer, there really isin't a problem with needed help from the
> furnace (which you won't get anyways because the furnace doesn't run in
> the summer). The water heater exhaust flow should have no problem
> getting up and out the chimney in the summer. Now if you have a reverse
> air-flow in the chimney, then nothing you can do to the chimney
> (including using a liner) is going to help with that.
Answer me this. Have you ever lit a fire in a fireplace?
Does the fireplace draw air the same when you light
the first piece of paper as it does when the fire is hot?
Do you think this principle is unique to a fireplace?
Or will a water heater on a correctly sized chimney have
a better draft because the hot air stays hot, fills the whole
chimney and rises, pulling more combustion products
behind it?
>
> So unless you know what type of furnace he has, and just how cold it
> gets where he lives, then you can't say that he *needs* a liner for his
> water heater exhaust.
Again, you must have a reading comprehension problem.
I never said he needs a chimney liner. I only said that
if the chimney is too large for what's connected to it,
then he needs a chimney liner.
>
> And like I said before, even in cold climates it's standard to have a
> non-lined chimney and have furnace and water-heater exhaust run
> passively up and out the chimney.
Uh huh.
> It's only when you have a
> high-efficiency furnace do you start to look at using a draft motor or a
> liner to help the water-heater exhaust.
Don't know what you're talking about here. I've never
heard of anyone looking at using a "draft motor" to
help the water heater exhaust. I've
heard of people buying high efficiency furnaces or
water heaters that have them.
>
> > And second, having the flue correctly sized to the appliance
> > helps create the correct draft.
>
> Fuck the draft, and the sizing. This isn't rocket science.
So says you, the ignoramus. The NFPA and local codes
say that while it isn't rocket science, it is science and
there are standards for chimney sizing related to what
it's connected to for safety and proper operation. A
chimney needs to be in a certain size range. Too big
or too small, neither is good.
>
> When you've got something creating a negative pressure in the house,
> causing reverse air-flow through the water heater flue, then you put
> down your books and graphs and tables and you fix the reverse air
> problem.
>
> > If the flue is sized correctly the hot gas stays hot and rises.
>
> Again, you're completely disregarding the whole point that started this
> thread.
Not disregarding anything here.
>
> This boob thinks that he's getting a breeze flowing into his water
> heater exhast flue and blowing out a match that he holds against the
> draft intake vent (presumably the gap between the water heater and the
> flue intake above it).
>
> None of your correctly-sized shit is going to make that breeze go away.
I'll leave it for others to decide who the real boob is here.
Vic Smith
<mike...@optonline.net> wrote:
>On Aug 23, 12:26 pm, Vic Smith <thismailautodele...@comcast.net>
>>
>> Probably getting around the basement sill plates, HVAC ducting and
>> piping, then up through the walls and into the attic.
>> In my house, circa 1959, none of that is sealed.
>> Haven't looked at the attic sills, but I'm sure they're not sealed
>> either.
>> I don't think they sell green plugs any more.
>> You have the right idea, but he should go after the basement overhead
>> first if wants to solve the attic fan induced downdraft in the water
>> heater vent.
>> Somebody wrote about a thermal switch between HW and attic fan and
>> that's a good solution too.
>> Personally, if the draft didn't take long to be established with the
>> attic fan running, I'd put the horizontal diverter back in.
>> This is what they look like, and Mike had one on his old heater.http://www.standexadp.com/specs.php?spec=28
>> That would prevent pilot blow-out and overheating the top of the tank.
>> I never had a pilot blow out with these but have with the hood style
>> diverter.
>> I'm not sure about spillage, but just guess it would be less.
>> You also need a CO detector nearby to play it safe.
>> This isn't a new draft problem, just a new water heater and venting.
>>
>> --Vic- Hide quoted text -
>>
>> - Show quoted text -
>
>What exactly does that diverter do? It is open on the bottom, right?
Diverts the backdraft, same thing the vertical hood diverter is
supposed to do.
But it works better.
There's a flat baffle plate that runs half way down the box,
interrupting the air/gas flow.
A backdraft hits that plate and dumps out the bottom of the box.
Never hits the top of the heater flue, where it can blow out the
pilot.
Hot gasses from the heater also hit the baffle, and drop down.
But those hot gases rise back up at the bottom of the baffle, and
continue up the vent..
Elegantly simple.
>Thats what I had on my old water heater. Plus whoever installed the
>previous water heater eliminated the draft hood for some reason, and
>just put the 3" duct directly on top of the exhaust outlet. Now I'm
>wondering if they did this because of the backdraft problem.
I saw somewhere that the hood type diverters came into play in 1992.
Your old heater was probably just an original installation.
Unless you know the heater was put in after that time.
I noticed the one in the pic showing your old installation, and
remembered examining and moving mine while doing some chimney sealing
in my old house. I figured out its purpose out of curiousity.
I also think I left it on when I put in a new heater with a dome vent.
But it is really amazing how you can find absolutely no information on
horizontal diverters on the net.
Everything I said is from memory, not the net.
All the so-called experts in the HVAC forums never mention it when
answering questions about how to stop downdraft from blowing out
pilots or melting plastic on the top of tanks.
Now me and the other folks in this group who happened to read this are
the only ones who know about horizontal diverters.
--Vic
Home Guy
> Now me and the other folks in this group who happened to read this
> are the only ones who know about horizontal diverters.
This guy doesn't need a horizontal diverter.
His pilot isin't being blown out.
If you've got a constant down-draft in the chimney caused by negative
air pressure inside the house, your horizontal divertor will do squat at
helping exhaust from the water heater to make it up and out the chimney.
So are you going to keep telling him he needs a horizontal divertor?
Vic Smith
>Vic Smith wrote:
>
>> Now me and the other folks in this group who happened to read this
>> are the only ones who know about horizontal diverters.
>
>This guy doesn't need a horizontal diverter.
>
>His pilot isin't being blown out.
>
I must have confused that with the match blowing out during his
testing, and all the crap I've read on the net.
>If you've got a constant down-draft in the chimney caused by negative
>air pressure inside the house, your horizontal divertor will do squat at
>helping exhaust from the water heater to make it up and out the chimney.
>
Maybe, maybe not. It for sure would dump the heat elsewhere instead
of melting the plastic atop his heater.
And he never said how long it took the draft to get established when
the heater went on with the attic fan running.
My reading indicates spillage is pretty standard for up to a minute.
>So are you going to keep telling him he needs a horizontal divertor?
Only if it's acceptable to him, and it works for him.
Since his pilot isn't blowing out it would just move spillage away
from the heater top. Burnt plastic atop the heater appears to be a
fairly common occurrence.
Here's my order of preference, "by the book."
1. Crack open a basement window during attic fan season.
Easy, and he said that works.
2. Thermal switch between heater and attic fan. Moderate job.
3. Seal the basement so attic fan has no effect. Big job.
4. Modify chimney for better draft - if possible. Big job.
Throwing out most of the book, here's what I'd do.
1. Crack open a window if it doesn't affect anything else.
2. If the cracked open window wasn't acceptable, I'd measure how long
it took a draft to establish with attic fan running.
If less than a minute I'd forget about it except to make sure I had a
working CO detector near the heater.
If the heat melting the plastic bothered me, I'd add a horizontal
diverter. Then I'd check spillage again.
That would the interesting part.
Anything I did that wouldn't keep spillage under a minute would get me
back to the "by the book" list.
--Vic
Home Guy
> > This guy doesn't need a horizontal diverter.
> >
> > His pilot isin't being blown out.
>
> I must have confused that with the match blowing out during his
> testing, and all the crap I've read on the net.
What the hell is wrong with you people?
He holds a match near the gap where his draft hood meets the water
heater, and the match goes out.
He says his pilot (way down at the bottom of the heater) does not get
blown out.
Why he even thought he should even check to see if he's getting a breeze
blowing out of the draft hood - I don't know.
> > If you've got a constant down-draft in the chimney caused by
> > negative air pressure inside the house, your horizontal divertor
> > will do squat at helping exhaust from the water heater to make
> > it up and out the chimney.
>
> Maybe, maybe not.
I see that basic physics is beyond your grasp.
> It for sure would dump the heat elsewhere
He doesn't have a problem with "dumping heat".
And by the way, if a divertor is dumping heat to some other place
besides the flue, what does that tell you about where you're dumping the
combustion exhaust gases?
> And he never said how long it took the draft to get established
> when the heater went on with the attic fan running.
I don't think he even said it ever gets established with the roof fan
running.
> > So are you going to keep telling him he needs a horizontal divertor?
>
> Only if it's acceptable to him, and it works for him.
He's a boob because he doesn't want to climb a ladder or pick up a saw
and cut some more holes in his soffit.
I wonder if he really knows how much of his soffet venting is actually
clear vs obstructed?
Does he have insulation jammed into the corners of the roof line,
obstructing his soffits?
He obviously must have a direct path in his house from attic to basement
that he doesn't know about.
> Since his pilot isn't blowing out it would just move spillage away
> from the heater top.
What spillage?
WTF are you talking about?
> Burnt plastic atop the heater appears to be a fairly common
> occurrence.
The OP (Mikepier) has NOT SAID (at least not in this thread) anything
about burnt or melted plastic on his water heater.
> Here's my order of preference, "by the book."
> 1. Crack open a basement window during attic fan season.
Bullshit.
If you don't have enough ventilation in the attic (soffits, gable ends)
then why bother running the roof fan in the first place?
> 2. Thermal switch between heater and attic fan. Moderate job.
More bullshit.
> 3. Seal the basement so attic fan has no effect. Big job.
He should find out why there is such an easy path between his attic
space and the rest of the house / basement, and close that path.
> 4. Modify chimney for better draft - if possible. Big job.
That won't help if there's still a negative pressure inside the house or
basement caused by the roof fan. Why is that concept so hard for you to
understand?
The **ONLY** way you can have proper drafting for the furnace and water
heater in his case if he allows his house to achieve a negative pressure
is to seal the room or the area where his furnace and water heater is,
and give them a new combustion air intake from the outside.
Or he can turn his furnace and water heater into a closed system by
bringing sealed ductwork directly to the combustion air intake vents or
the cabinets and running that ductwork to a dedicated outside air
intake, and then use lots of aluminized tape to seal up his furnace and
water heater so there is a completely closed path from from the outside
air intake to the furnace / WH to the exaust flue to the chimney.
tra...@optonline.net
> Vic Smith wrote:
> > > This guy doesn't need a horizontal diverter.
>
> > > His pilot isin't being blown out.
>
> > I must have confused that with the match blowing out during his
> > testing, and all the crap I've read on the net.
>
> What the hell is wrong with you people?
>
> He holds a match near the gap where his draft hood meets the water
> heater, and the match goes out.
>
> He says his pilot (way down at the bottom of the heater) does not get
> blown out.
>
> Why he even thought he should even check to see if he's getting a breeze
> blowing out of the draft hood - I don't know.
What the hell is wrong with you people? He told us he
started checking because he noticed the plastic
on the pipes at the top of the water heater were melted.
He sure did in the other thread he referred to when he made
the first post in this thread. I even gave you a link to it
yesterday. I would think a guy who's so interested in this
and spends half his time cursing and calling other people
lazy boobs would have read it by now. But obviously that is
expecting too much
>
> > Here's my order of preference, "by the book."
> > 1. Crack open a basement window during attic fan season.
>
> Bullshit.
>
> If you don't have enough ventilation in the attic (soffits, gable ends)
> then why bother running the roof fan in the first place?
>
> > 2. Thermal switch between heater and attic fan. Moderate job.
>
> More bullshit.
>
> > 3. Seal the basement so attic fan has no effect. Big job.
>
> He should find out why there is such an easy path between his attic
> space and the rest of the house / basement, and close that path.
>
> > 4. Modify chimney for better draft - if possible. Big job.
>
> That won't help if there's still a negative pressure inside the house or
> basement caused by the roof fan. Why is that concept so hard for you to
> understand?
>
> The **ONLY** way you can have proper drafting for the furnace and water
> heater in his case if he allows his house to achieve a negative pressure
> is to seal the room or the area where his furnace and water heater is,
> and give them a new combustion air intake from the outside.
Nonsense. You can get proper drafting by providing a fixed
ventilation
opening to outside for the basement in the area of the water heater
and furnace.
>
> Or he can turn his furnace and water heater into a closed system by
> bringing sealed ductwork directly to the combustion air intake vents or
> the cabinets and running that ductwork to a dedicated outside air
> intake, and then use lots of aluminized tape to seal up his furnace and
> water heater so there is a completely closed path from from the outside
> air intake to the furnace / WH to the exaust flue to the chimney.
I'm sure that hack job with tape will impress the code inspector
or the home inspector if he sells the place.
But what should we expect from the guy who claims that proper
chimney sizing for appliances doesn't matter.
Home Guy
> What the hell is wrong with you people? He told us he
> started checking because he noticed the plastic
> on the pipes at the top of the water heater were melted.
I don't know what you're talking about.
The ONLY posts that I see Mikepier posting in is this thread, with the
subject "Putting speed control on attic fan". If he started an older
thread about melted plastic on water heaters, then I didn't read it at
the time, or he didn't post it to this newsgroup.
He hasn't said anything about melted plastic in this thread.
> > The OP (Mikepier) has NOT SAID (at least not in this thread)
> > anything about burnt or melted plastic on his water heater.
>
> He sure did in the other thread he referred to when he made
> the first post in this thread.
Read my statement more carefully. I said "at least not in this thread".
My 4-year-old water heater also has melted disks of read and blue
plastic surrounding the two water pipes (hot and cold) at the top of the
tank. I don't have a negative air-pressure situation in the house. The
melted plastic doesn't bother me.
> > The **ONLY** way you can have proper drafting for the furnace and
> > water heater in his case if he allows his house to achieve a negative
> > pressure is to seal the room or the area where his furnace and water
> > heater is, and give them a new combustion air intake from the outside.
>
> Nonsense. You can get proper drafting by providing a fixed
> ventilation opening to outside for the basement in the area of
> the water heater and furnace.
Why can't you read properly?
Look what I said:
"and give them a new combustion air intake from the outside"
Look what you just wrote:
"by providing a fixed ventilation opening to outside for the basement"
You look like a fool when you disagree with me, and then go on to give
the same answer using different wording.
> > Or he can turn his furnace and water heater into a closed system by
> > bringing sealed ductwork directly to the combustion air intake
> > vents or the cabinets and running that ductwork to a dedicated
> > outside air intake, and then use lots of aluminized tape to seal up
> > his furnace and water heater so there is a completely closed path
> > from from the outside air intake to the furnace / WH to the exaust
> > flue to the chimney.
>
> I'm sure that hack job with tape will impress the code inspector
> or the home inspector if he sells the place.
If he doesn't want to actually fix his home's internal air circulation
and attic venting problem, then he doesn't have many other alternatives
to deal with a negative air pressure. I'm not saying that pulling a
rube-goldberg ductwork job on his water heater and furnace is the first
thing he should do - I'm saying it's the last thing he should do.
> But what should we expect from the guy who claims that proper
> chimney sizing for appliances doesn't matter.
It doesn't matter when you've got a negative air-pressure situation in
the house that you need to deal with first.
tra...@optonline.net
> "trad...@optonline.net" wrote:
> > What the hell is wrong with you people? He told us he
> > started checking because he noticed the plastic
> > on the pipes at the top of the water heater were melted.
>
> I don't know what you're talking about.
>
> The ONLY posts that I see Mikepier posting in is this thread, with the
> subject "Putting speed control on attic fan". If he started an older
> thread about melted plastic on water heaters, then I didn't read it at
> the time, or he didn't post it to this newsgroup.
>
> He hasn't said anything about melted plastic in this thread.
His first words in this thread were:
"A few weeks ago I posted a problem with too much negative air
pressure
in my house caused by my attic fan."
I even provided youi with a direct link to that post yesterday.
Seems for someone so interested you would take a look.
>
> > > The OP (Mikepier) has NOT SAID (at least not in this thread)
> > > anything about burnt or melted plastic on his water heater.
>
> > He sure did in the other thread he referred to when he made
> > the first post in this thread.
>
> Read my statement more carefully. I said "at least not in this thread".
Still to lazy to read the other thread?
>
> My 4-year-old water heater also has melted disks of read and blue
> plastic surrounding the two water pipes (hot and cold) at the top of the
> tank. I don't have a negative air-pressure situation in the house. The
> melted plastic doesn't bother me.
>
> > > The **ONLY** way you can have proper drafting for the furnace and
> > > water heater in his case if he allows his house to achieve a negative
> > > pressure is to seal the room or the area where his furnace and water
> > > heater is, and give them a new combustion air intake from the outside.
>
> > Nonsense. You can get proper drafting by providing a fixed
> > ventilation opening to outside for the basement in the area of
> > the water heater and furnace.
>
> Why can't you read properly?
>
> Look what I said:
>
> "and give them a new combustion air intake from the outside"
>
> Look what you just wrote:
>
> "by providing a fixed ventilation opening to outside for the basement"
>
> You look like a fool when you disagree with me, and then go on to give
> the same answer using different wording.
Not the same answer at all, you claimed he had to seal
the area around the water heater or the room. He's already
proven that just opening a basement window fixes it.
>
> > > Or he can turn his furnace and water heater into a closed system by
> > > bringing sealed ductwork directly to the combustion air intake
> > > vents or the cabinets and running that ductwork to a dedicated
> > > outside air intake, and then use lots of aluminized tape to seal up
> > > his furnace and water heater so there is a completely closed path
> > > from from the outside air intake to the furnace / WH to the exaust
> > > flue to the chimney.
>
> > I'm sure that hack job with tape will impress the code inspector
> > or the home inspector if he sells the place.
>
> If he doesn't want to actually fix his home's internal air circulation
> and attic venting problem, then he doesn't have many other alternatives
> to deal with a negative air pressure. I'm not saying that pulling a
> rube-goldberg ductwork job on his water heater and furnace is the first
> thing he should do - I'm saying it's the last thing he should do.
You didn't specify first or last, you just said he should do
it. Whether it's first or last, I think everyone else here
would agree that it's wrong to be using tape to fashion
some kind of hack job connection from the water heater
and furnace to outside air. You think that will pass
inspection?
>
> > But what should we expect from the guy who claims that proper
> > chimney sizing for appliances doesn't matter.
>
> It doesn't matter when you've got a negative air-pressure situation in
> the house that you need to deal with first.
Again, there was no qualification in your blanket statement saying
that correct chimney sizing does not matter. Correct chimney
sizing does matter, as you've apparently now learned, so you're
trying to now get around it with a qualification.
That's like saying it doesn't matter
if you use a ground conductor to carry current because someone
is having a problem with a switch. Code is code and it always
applies.
Vic Smith
>Vic Smith wrote:
>
>
>> > If you've got a constant down-draft in the chimney caused by
>> > negative air pressure inside the house, your horizontal divertor
>> > will do squat at helping exhaust from the water heater to make
>> > it up and out the chimney.
>>
>> Maybe, maybe not.
>
>I see that basic physics is beyond your grasp.
>
You've probably never seen a horizontal diverter.
I can make a good case why they're better than a dome for establishing
draft, but won't
And why do you think a downdraft that blows out a match can't be
overcome with heat to establish an updraft?
Lots of houses have negative pressure.
Depends how bad it is.
>> It for sure would dump the heat elsewhere
>
>He doesn't have a problem with "dumping heat".
>
That's what melted the plastic on top of his heater.
He seems to think that's a problem.
I wouldn't like it if it happened to mine.
>And by the way, if a divertor is dumping heat to some other place
>besides the flue, what does that tell you about where you're dumping the
>combustion exhaust gases?
>
I don't want to confuse you here, and since I don't have all the info
from Mike I could be wrong.
This assumes he had the same attic fan running before with the old
heater and hasn't tightened up the house.
The downdraft existed before and nobody was poisoned by CO.
He only noticed it now because with the horizontal diverter gone
the dome diverter on the new tank spilled enough heat before it
established a draft to eventually melt the plastic.
If he has a working CO alarm and there was no draft established
it would have went off.
Mine went off when a squirrel got in the vent.
Mike can say if my assumptions are wrong.
>> And he never said how long it took the draft to get established
>> when the heater went on with the attic fan running.
>
>I don't think he even said it ever gets established with the roof fan
>running.
>
I don't think he tried. He's not too talkative.
But if he has a CO alarm and no draft with a firing heater it would go
off. And he'd most likely smell it and feel the heat if he was
nearby.
snip soffit vent stuff.
>
>> Since his pilot isn't blowing out it would just move spillage away
>> from the heater top.
>
>What spillage?
>
>WTF are you talking about?
>
That's what HVAC guys call gases escaping diverters until draft is
established.
They also test with negative pressure in the appliance room.
http://virginiahomeperformance.com/yahoo_site_admin/assets/docs/Gold_Sheet.185172811.pdf
You can get an idea of how many houses are under negative pressure
here. Pretty good study they did when homes were near an airport were
soundproofed.
http://www.state.mn.us/mn/externalDocs/Commerce/Ventilation_and_Depressurization_Research_022003031343_VentilationReport.pdf
>> Burnt plastic atop the heater appears to be a fairly common
>> occurrence.
>
>The OP (Mikepier) has NOT SAID (at least not in this thread) anything
>about burnt or melted plastic on his water heater.
>
He mentioned it in a prior thread.
>> Here's my order of preference, "by the book."
>> 1. Crack open a basement window during attic fan season.
>
>Bullshit.
>
Got no idea why you say that. It already worked for him.
>If you don't have enough ventilation in the attic (soffits, gable ends)
>then why bother running the roof fan in the first place?
>
So you think that because an attic fan causes some negative pressure
in the basement it's not cooling the attic? Nonsense.
>> 2. Thermal switch between heater and attic fan. Moderate job.
>
>More bullshit.
>
Somebody else did it to solve the problem.
>> 3. Seal the basement so attic fan has no effect. Big job.
>
>He should find out why there is such an easy path between his attic
>space and the rest of the house / basement, and close that path.
>
Already been covered, And it doesn't have to be an "easy" path.
Older houses have hundreds of paths where air can migrate.
>> 4. Modify chimney for better draft - if possible. Big job.
>
>That won't help if there's still a negative pressure inside the house or
>basement caused by the roof fan. Why is that concept so hard for you to
>understand?
>
You still don't understand a negative draft can be reversed by heat.
--Vic
Vic Smith
>
>My 4-year-old water heater also has melted disks of read and blue
>plastic surrounding the two water pipes (hot and cold) at the top of the
>tank. I don't have a negative air-pressure situation in the house. The
>melted plastic doesn't bother me.
>
Sound like you have bad draft. Shouldn't be that much spillage.
Probably won't matter though.
Do you have a CO alarm? That's a good safety measure.
--Vic
Sjouke Burry
> A few weeks ago I posted a problem with too much negative air pressure
> similiar to this.
>
>
> I wanted to get somekind of speed controller to slow down the speed of
> the fan. I've seen them on Broan's website, and they are rated for 6
> amps.
> Any issues if I put the motor on a rheostat? Are these motors designed
> to work on low voltage?
No. The frequency of the mains controls the speed.
The voltage has minor influence, and low voltage can damage the motor
by overheating it.
Bob F
>> If the attic fan is being used as a whole house fan, you need to
>> open more windows when you run it. If you are using air conditioning
>> at the same time as the attic fan, the leakage into the attic is
>> just throwing cooling money away through it.
>
> In my situation however, I think the attic fan helps with the A/C on.
> My house was originally installed with force hot air heat, with the
> supply ducts low to the ground. Like many other people in my
> neighborhood, I added on Central A/C using the existing ductwork.
> Because the return vent is low on the floor along with the supply
> vents, I think the attic fan "draws" that air upwards, making it feel
> cooler. I could be wrong though.
It may make it feel cooler, but it most likely makes the A/C run a lot more.
Bob F
> I always call my whole house fan, an attic fan, because that's what
> it is, in the attic.
>
Which may totally mislead people you are trying to communicate with.
There is a difference.
rma...@gmail.com
gfre...@aol.com
>Why doesn't sombody answer the original question. Can you put a speed control on a roof fan
determine speed based on the windings in the motor and the frequency
of the line voltage. You could do some adjustment with a VFD but at a
certain point the motor will not be going fast enough to limit
current.
It would be cheaper to buy a 4 speed blower motor and use a rotary
switch.
Scott Lurndal
>Why doesn't sombody answer the original question. Can you put a speed control on a roof fan
to make a workable recommendation.
For example, one needs to know exactly what _kind_ of motor (e.g. universal
or induction) is being used. The brand and model of the fan would also
be useful.
trader_4
find a replacement multi-speed motor that fits. Easier solution is
probably to get a fan with less CFM or even better, increase the available
air inlets. If it's a reasonable size fan to begin with, what's the
point to slowing it down? It's going to move less air and not do what
it's supposed to do.
Tony944
Motors which use start capacitor or internal switch no you can not, but you
can
get taped motor and use of switch from one tap to other, or you can use
same motor
hooked up to highest speed and use Variable speed control on it with (Triac)
out put
Variable Light dimmer that have Triac output will also work on Shaded pole
Motor
wrote in message
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cl...@snyder.on.ca
More info required.
hig...@aol.com
Tony944
sucked carbon monoxide in
because you are making up air through the exhaust of HWH. Suggestion get
some one who knows
how Ventilation works. It is better to pay then being dead.
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