Radiators sucking air in?
Peter A. Chapman
I have three third-floor radiators. Rather than expelling air or hot water
when you open the little screw valve on the side, they have now started
to suck air in. The system was turned on just about a month ago and it
started getting much colder this past week. At present, the radiators on
the 3rd floor never get hot, just warm half-way up from the floor. Can
anybody explain what's happening? I don't buy my daughter's, "well, Dad,
maybe radiators just suck," hypothesis. Thanks!
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Peter A. Chapman pe...@bankrupt.com http://bankrupt.com
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richard deno
In <56mtf5$5...@earth.njcc.com> pe...@bankrupt.com (Peter A. Chapman)
writes:
>I have three third-floor radiators. Rather than expelling air or hot
water
>when you open the little screw valve on the side, they have now
started
>to suck air in. The system was turned on just about a month ago and
it
>started getting much colder this past week. At present, the radiators
on
>the 3rd floor never get hot, just warm half-way up from the floor.
Can
>anybody explain what's happening? I don't buy my daughter's, "well,
Dad,
>maybe radiators just suck," hypothesis. Thanks!
>
>----------------------------------------------------------------------
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http://bankrupt.com
>----------------------------------------------------------------------
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>
probably the presure reducing valve is pluged with dirt, or some one
has tured the water off.
Danny Bolt
The boiler pressure is too low. Is the valve open to the pressure
limiting valve? Pressure should be about 12 psi. Maybe a little more
if you have third floor radiators.
Dan Bolt, Des Moines
Jeffrey C. May
In article <56mtf5$5...@earth.njcc.com>, pe...@bankrupt.com (Peter A.
Chapman) wrote:
> I have three third-floor radiators. Rather than expelling air or hot water
> when you open the little screw valve on the side, they have now started
> to suck air in. The system was turned on just about a month ago and it
> started getting much colder this past week. At present, the radiators on
> the 3rd floor never get hot, just warm half-way up from the floor. Can
> anybody explain what's happening? I don't buy my daughter's, "well, Dad,
> maybe radiators just suck," hypothesis. Thanks!
>
> ------------------------------------------------------------------------------
> Peter A. Chapman pe...@bankrupt.com http://bankrupt.com
> ------------------------------------------------------------------------------
Peter,
the pressure is not high enough. Gauge reading of 15 psi is equivalent
of one atmsophere of pressure, or 35 feet of water column height.
Alternatively, feed may be clogged, so even though you have bleed open, no
water pressure available to fill. Check fill valve, pressure.
Mick Natco
Your hot water heating system has two components (among many others)
that need to be operating properly to get heat to your third floor.
There is a pressure reducing valve that is set when the boiler is cold
and not operating to 12 psi. Why 12 psi? Because, at that pressure you
are able to drive a column of water (the heating water in your pipes)
30 feet above the lowest point in the system.
Secondly, depending on the age of your system (I'm assuming older if
you meant cast iron radiators) you will have an expansion tank that is
either a large (20 to 40 gallon) tank suspended laterally between the
joists, probably above the boiler, or you will have a much smaller
(physically maybe 2 to 4 gallons) bladder type expansion tank that is
the equivalent (by virtue of its internal pressurized bladder) of the
first type. (Very early system used an attic mounted open tank in an
open system for expansion of water or a column of mercury mounted high
in the system)
1. If your pressure reducing valve is not maintaining the minimum
pressure when the boiler is cold than it can't push the water to the
third floor.
2. If the expansion tank isn't functioning properly (standard tank
filled with water leaving no room for expansion, or bladder broken in
bladder tank) you will have a situation where the system pressure
during heating will exceed the normal range (12 to 15 or 20 psi) and
may even go high enough (30 plus psi) for the blow-off valve to
release the excess pressure by blowing off some water. When that
happens cold water is brought into the system reducing the temperature
and pressure in the system. Unfortunately, most water has considerable
dissolved oxygen which eventually works it's way out adding air to the
system which settles in the highest point, your third floor radiators.
So, what should you do?
Most pressure reducing valves have either a bypass loop around the
valve or a bail handle on the valve itself that allows the
introduction of water at house pressure. If your working alone, enable
this bypass till the system pressure reads 30 psi (GOOD time to check
and see if your emergency relief is working properly, it should blow
around 30 psi or a little above and reset itself when the pressure
drops a little. If it doesn't or doesn't reset properly after a short
while REPLACE it). When you've reached 30 psi shut off the bypass
circuit ( but not the main 12 psi circuit) and go to the third floor
radiators and bleed them. You'll probably have to do this several
times before you get them bled.
If your working with someone else, have them control the bypass and
maintain pressure at a constant 30 psi while you bleed the radiators.
You can release the excess pressure after you've bled the radiators
from the drain valve on the boiler.
Now let the system go cold, adjust pressure to 12 psi and shut off the
water supply to the boiler (CAUTION HERE don't do this unless your
going to be there to observe), fire it up and let it run hard for
several hours (crank the thermostat all the way up) to get the whole
system hot (180 plus °), than shut it off and let it cool. If the
pressure drops below 12 psi on the way down, it probably also went
pretty high on the way up, and your blow-off may have tripped at some
point. If all your radiators were hot during this test than you can
assume your bladder tank needs replacement or your standard tank needs
to be drained. Standard expansion tanks work on the principle of
maintaining a cushion of air above the water in the tank, this cushion
is used to stabilize the pressure in the system. Over time the air in
the tank can be absorbed into the water thus reducing the tanks
capacity to buffer this expansion. Hopefully there will be a valve
that will allow you to turn off the standard tank (so you don't have
to drain the whole system just to drain the tank).
PS Don't discount the pessibility of a leak somewhere.
Two personal observations
1. In a system with cast iron radiators, your dealing with a much
larger volume of water and I have always preferred a standard type
expansion tank or the LARGEST bladder tank available. ( If your system
requires a 20 gallon bladder tank, get something twice that size if
possible (depending on how your system is set up [available space]).
You will notice less pressure fluctuation.
2. I've always used 14 or 15 psi as my base rather than 12. I've
always found 12 psi marginal at maintaining full radiators on the
third floor.
Hope this helps
Mick Natco
mna...@pantek.com
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Bill Burdick
I have a similar system in my house, third floor and all. To add to
the other posters' suggestions: the problem is that you need to add
water to the boiler to displace the air you will bleed out. For a
three story house, you want about 13-15 psi cold fill pressure (i.e.
when the radiators are cool); a bit more when the system is hot. Add
water when the system is cool and the burner is not firing. I usually
shut off the burner and start the circulator before adding cold water,
to prevent thermal shock to the boiler. Most modern systems have a
pressure reducing valve between the domestic cold water piping and the
boiler, which acts as an automatic fill valve to maintain correct
boiler pressure, even when you bleed air out. Many older systems,
however, have only a manual fill valve. You may need to add water
manually to bring up the pressure when bleeding air.
pe...@bankrupt.com (Peter A. Chapman) wrote:
>I have three third-floor radiators. Rather than expelling air or hot water
>when you open the little screw valve on the side, they have now started
>to suck air in. The system was turned on just about a month ago and it
>started getting much colder this past week. At present, the radiators on
>the 3rd floor never get hot, just warm half-way up from the floor. Can
>anybody explain what's happening? I don't buy my daughter's, "well, Dad,
>maybe radiators just suck," hypothesis. Thanks!
>------------------------------------------------------------------------------
>Peter A. Chapman pe...@bankrupt.com http://bankrupt.com
>------------------------------------------------------------------------------
-------------------------------------------------------------
"In Vino Veritas"
Bill Burdick
The email address in my header is false. Reply to:
bburd AT voicenet.com (insert @ symbol)
Nobody has permission to send me email advertising or
put me on a mass mailing list of any kind!
dri...@slic.com
jm...@cybercom.net (Jeffrey C. May) wrote:
>In article <56mtf5$5...@earth.njcc.com>, pe...@bankrupt.com (Peter A.
>Chapman) wrote:
>> I have three third-floor radiators. Rather than expelling air or hot water
>> when you open the little screw valve on the side, they have now started
>> to suck air in. The system was turned on just about a month ago and it
>> started getting much colder this past week. At present, the radiators on
>> the 3rd floor never get hot, just warm half-way up from the floor. Can
>> anybody explain what's happening? I don't buy my daughter's, "well, Dad,
>> maybe radiators just suck," hypothesis. Thanks!
>>
>> ------------------------------------------------------------------------------
>> Peter A. Chapman pe...@bankrupt.com http://bankrupt.com
>> ------------------------------------------------------------------------------
>Peter,
> the pressure is not high enough. Gauge reading of 15 psi is equivalent
>of one atmsophere of pressure, or 35 feet of water column height.
>Alternatively, feed may be clogged, so even though you have bleed open, no
>water pressure available to fill. Check fill valve, pressure.
>jm...@cybercom.net
Yup...
I've had that problem with tall houses in the past. Bring your
pressure up to 20 psi at the boiler. It'll help keep the water up
where it belongs.
Just for arguement..... 1 psi is equal to 2.31 ft of water and for
every foot of water in any column you incur .4333 pouinds of pressure.
So.....if the highest radiator in your place is say, 40 feet at the
top of the radiator to the guage in the cellar you'd need at least
17.5 lbs. on your guage in the cellar. Crank it up to 20 and you
should be alright.
scott
Bill Burdick wrote:
>
> I have a similar system in my house, third floor and all. To add to
> the other posters' suggestions: the problem is that you need to add
> water to the boiler to displace the air you will bleed out. For a
> three story house, you want about 13-15 psi cold fill pressure (i.e.
> when the radiators are cool); a bit more when the system is hot. Add
> water when the system is cool and the burner is not firing. I usually
> shut off the burner and start the circulator before adding cold water,
> to prevent thermal shock to the boiler. Most modern systems have a
> pressure reducing valve between the domestic cold water piping and the
> boiler, which acts as an automatic fill valve to maintain correct
> boiler pressure, even when you bleed air out. Many older systems,
> however, have only a manual fill valve. You may need to add water
> manually to bring up the pressure when bleeding air.
>
>
> >I have three third-floor radiators. Rather than expelling air or hot water
> >when you open the little screw valve on the side, they have now started
> >to suck air in. The system was turned on just about a month ago and it
> >started getting much colder this past week. At present, the radiators on
> >the 3rd floor never get hot, just warm half-way up from the floor. Can
> >anybody explain what's happening? I don't buy my daughter's, "well, Dad,
> >maybe radiators just suck," hypothesis. Thanks!
>
> >------------------------------------------------------------------------------
> >Peter A. Chapman pe...@bankrupt.com http://bankrupt.com
> >------------------------------------------------------------------------------
>
> "In Vino Veritas"
> Bill Burdick
>
> The email address in my header is false. Reply to:
> bburd AT voicenet.com (insert @ symbol)
>
> Nobody has permission to send me email advertising or
> put me on a mass mailing list of any kind!
I agree with bill burdick..no bias here.....
Robert Thompson
In article <56qo5t$5...@winthrop.slic.com>, dri...@slic.com says...>>In article <56mtf5$5...@earth.njcc.com>, pe...@bankrupt.com (Peter A.
>>Chapman) wrote:
>
>>> I have three third-floor radiators. Rather than expelling air or hot
water
>>> when you open the little screw valve on the side, they have now
started
>>> to suck air in. The system was turned on just about a month ago and
it
>>> started getting much colder this past week. At present, the radiators
on
>>> the 3rd floor never get hot, just warm half-way up from the floor.
Can
>>> anybody explain what's happening? I don't buy my daughter's, "well,
Dad,
>>> maybe radiators just suck," hypothesis. Thanks!
>>>
>>>
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---
>-
>>> Peter A. Chapman pe...@bankrupt.com
http://bankrupt.co
>m
>>>
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---
>-
>
>> the pressure is not high enough. Gauge reading of 15 psi is
equivalent
>>of one atmsophere of pressure, or 35 feet of water column height.
>>Alternatively, feed may be clogged, so even though you have bleed open,
no
>>water pressure available to fill. Check fill valve, pressure.
>
>>jm...@cybercom.net
>Yup...
>I've had that problem with tall houses in the past. Bring your
>pressure up to 20 psi at the boiler. It'll help keep the water up
>where it belongs.
>Just for arguement..... 1 psi is equal to 2.31 ft of water and for
>every foot of water in any column you incur .4333 pouinds of pressure.
>So.....if the highest radiator in your place is say, 40 feet at the
>top of the radiator to the guage in the cellar you'd need at least
>17.5 lbs. on your guage in the cellar. Crank it up to 20 and you
>should be alright.
>
>
Well.... If you are pumping 40ft up in a closed system, you have 40 ft of
water pressing down on the inlet of the pump so height doesn't really
matter. The only real pressure loss you will have will be from your air
sperator. radiator, piping, boiler, balancing valves etc.
Robert Thompson
>>
>>>Peter,
>>> the pressure is not high enough. Gauge reading of 15 psi is
>equivalent
>>>of one atmsophere of pressure, or 35 feet of water column height.
>>>Alternatively, feed may be clogged, so even though you have bleed open,
>no
>>>water pressure available to fill. Check fill valve, pressure.
>>
>>>jm...@cybercom.net
>>Yup...
>>I've had that problem with tall houses in the past. Bring your
>>pressure up to 20 psi at the boiler. It'll help keep the water up
>>where it belongs.
>>Just for arguement..... 1 psi is equal to 2.31 ft of water and for
>>every foot of water in any column you incur .4333 pouinds of pressure.
>>So.....if the highest radiator in your place is say, 40 feet at the
>>top of the radiator to the guage in the cellar you'd need at least
>>17.5 lbs. on your guage in the cellar. Crank it up to 20 and you
>>should be alright.
>>
>>
>
>Well.... If you are pumping 40ft up in a closed system, you have 40 ft of
>water pressing down on the inlet of the pump so height doesn't really
>matter. The only real pressure loss you will have will be from your air
>sperator. radiator, piping, boiler, balancing valves etc.
>
>
Okay.. I've been behind my desk for too long today. please disregard
my last message. Just trying to sound more intelligent than I am. How do
you delete these newsgroup messages anyways?
Patrick May
pe...@bankrupt.com (Peter A. Chapman) wrote:
>I have three third-floor radiators. Rather than expelling air or hot water
>when you open the little screw valve on the side, they have now started
>to suck air in. The system was turned on just about a month ago and it
>started getting much colder this past week. At present, the radiators on
>the 3rd floor never get hot, just warm half-way up from the floor. Can
>anybody explain what's happening? I don't buy my daughter's, "well, Dad,
>maybe radiators just suck," hypothesis. Thanks!
>------------------------------------------------------------------------------
>Peter A. Chapman pe...@bankrupt.com http://bankrupt.com
>------------------------------------------------------------------------------
The first place to check for your problem is the water pressure in the
system. On the third floor your radiators are probably 20-30 feet
above your recirc pump. Water column water pressure is lost at a rate
of .433 PSI per foot. Every 27.75 inches of rise in the water column
you lose one pound per square inch. Therefore to get water to a
radiator 30 feet above the recirc pump your system pressure should be
at least 15 PSI. You will lose 13 pounds of that pressure in the rise.
Check to see what your relief valve pressure is before raising the
pressure. The probable cause for this problem is the feed water
regulator gets mucked up with residue and quits feeding the system to
the set pressure over time. Hope this helps ya.
Take care
Ric May Service Tech
Craft Mechanical
Lafayette Indiana
Ric May
Service Technician for Craft Mechanical, Lafayette Indiana
Plumbers & Pipefitters Local 157
Steve...
Hey Pete
I think you are low on water. Do you have a pump on the system...If so,
are you checking on the suction side of the pump or the discharge. I am
willing to bet you are out of water. How do you heat the water with a tube
bundle(heat exchanger) or a boiler. Let me know some of the particulars
and maybe I can help you out a little better. Steve
Peter A. Chapman <pe...@bankrupt.com> wrote in article
<56mtf5$5...@earth.njcc.com>...
Trelane
On 17 Nov 1996 11:38:13 GMT, pe...@bankrupt.com (Peter A. Chapman)
wrote:
>I have three third-floor radiators. Rather than expelling air or hot water
>when you open the little screw valve on the side, they have now started
>to suck air in. The system was turned on just about a month ago and it
>started getting much colder this past week. At present, the radiators on
>the 3rd floor never get hot, just warm half-way up from the floor. Can
>anybody explain what's happening? I don't buy my daughter's, "well, Dad,
>maybe radiators just suck," hypothesis. Thanks!
Boiler pressure is too low! It should be 20 to 25 psi for a three
story building.
Rick Rogers
What pressure are you operating the system at?