Fan Blowing Over Hot-Water Radiator?
Bob77869
Hi,
I have an old fashioned hot-water room radiator. I want to increase the heat
output into the room. My question is, will it help any to have a fan blowing
over the radiator? Say, a very small fan sitting on the floor behind the
radiator blowing into the room?
I have read many things that are suppose to help increase the heat transfer and
heat ouput. I read about removing the radiator cover, stripping and repainting
with matte black radiator paint, bleeding the radiator periodically, keeping it
clean and dusted, and adding radiator reflectors on the floor and walls behind
the radiator. However, I have not heard mention of the use of a fan. Why does
no one talk about it? A car uses a fan over the radiator. Doesnt it make sense
that a fan over a home radiator would increase heat transfer in the same way as
a car?
Also, if anyone has any ideas on how to get more output from a radiator, I
would greatly appreciate it! I dont want to freeze again this winter!
Thanks very much.
Bob
Don Ocean
These radiator
cases are about 2 feet by 2 feet by 8 inches....contain a car type
radiator and a 115v
fan with a permanent set thermodisk to control fan when hot. Usually
within very close proximity to the boiler and usually pointed toward
laundry area. Soooo... I would guess
a fireplace type circulator would enhance your heating experience.
Should you try out some experimantal fans....Please keep us posted as to
your findings.
Don Ocean
Sioux Falls, SD
Dan Murphy
Bob77869 wrote:
> A car uses a fan over the radiator. Doesnt it make sense
> that a fan over a home radiator would increase heat transfer in the same way as
> a car?
>
> Also, if anyone has any ideas on how to get more output from a radiator, I
> would greatly appreciate it! I dont want to freeze again this winter!
>
> Thanks very much.
>
> Bob
Makes sense to a point. But you cannot get more heat out of something than it has
going into it. That could ultimately be your problem. Give it a shot and let us
know how it did.
Dan
Bob77869
Thanks Dan.
Maye you are right. But, those things I listed, I havent tried any of them yet.
So, Im sure there is more I can get out of it. I mean, my radiators are dusty,
have massive covers on them, havent been bleed... Last year I just worked on
insulating my windows and getting the drafts down. So, this year Im going to
focus on the radiators. If anyone knows if putting a small fan on them will
help or not I would like to know. I wondered if the physics of home radiators
was somehow different from cars or what. Maybe what you are saying is the
problem, maybe home radiators are pleanty good at transfering the heat when you
give them the chance and blowing more air wont help. I just thought someone
here might know. If it wont help, I really dont want to do it. Then it will
just be a waste of electricity.
Alan Muller
bob7...@aol.com (Bob77869) wrote:
>
> Hi,
>
> I have an old fashioned hot-water room radiator. I want to increase
the heat
> output into the room. My question is, will it help any to have a fan
blowing
> over the radiator? Say, a very small fan sitting on the floor behind
the
> radiator blowing into the room?
Yes, this will work well, and is very easy to try. Just get a box fan
and set it in front of the radiator, raised a few inches. This will
greatly increase heat transfer to the air. This is not very neat as a
permanent solution but it will probably keep you warm.
am
Sent via Deja.com http://www.deja.com/
Before you buy.
Bob77869
Thanks Alan!
Please excuse my stupidty, but what exactly is a box fan? And where can I get
one? I was just going to go to radio shack or somewhere like that and see what
they had. Actually I was thinking a fan like are use inside computers would be
nice. Just a little thing that would be very quiet and small. But, I dont know
if I could find a 110v fan like that.
Alan Muller
bob7...@aol.com (Bob77869) wrote:
>
> Thanks Alan!
>
> Please excuse my stupidty, but what exactly is a box fan? And where
can I get
> one? I was just going to go to radio shack or somewhere like that and
see what
> they had. Actually I was thinking a fan like are use inside computers
would be
> nice. Just a little thing that would be very quiet and small. But, I
dont know
> if I could find a 110v fan like that.
ventilate in warm weather. They are cheap, especially at this time of
year. Remember, you want to move air over as much of the radiator as
you can. I suppose you could use a row of computer cooling fans under
the radiator, but it would be a lot more trouble to set up, and somewhat
noisy.
The Building Inspectors, Inc.
should be sized for the room. I'd make surer it isn't full of air and
consider removing the radiator cover. Radiator covers convert radiators
into convectors and generally screw up the characteristics of the system.
Radiator covers are a work of the devil, IMHO.
Dan
"Bob77869" <bob7...@aol.com> wrote in message
news:20001005194402...@ng-cg1.aol.com...
>
> Hi,
>
> I have an old fashioned hot-water room radiator. I want to increase the
heat
> output into the room. My question is, will it help any to have a fan
blowing
> over the radiator? Say, a very small fan sitting on the floor behind the
> radiator blowing into the room?
>
> I have read many things that are suppose to help increase the heat
transfer and
> heat ouput. I read about removing the radiator cover, stripping and
repainting
> with matte black radiator paint, bleeding the radiator periodically,
keeping it
> clean and dusted, and adding radiator reflectors on the floor and walls
behind
> the radiator. However, I have not heard mention of the use of a fan. Why
does
> no one talk about it? A car uses a fan over the radiator. Doesnt it make
VOJ
would be almost useless.
The reason a fan would help is that heat transfer (from radiator to air) is
dependant on the difference in temperature. With perfectly still air, a
layer of hot air sits around the radiator. If the radiator is not confined,
that air should rise pulling cold air from the floor.
The first thing you should do is make sure that there is no restriction of
airflow around, under or over the radiator.
Example: Little lady stuffed rags under the radiator preventing air from
coming up through the bottom. Why? Because the radiator got hotter. Of
course, the air wasn't taking the heat away.
If you have a ceiling fan in the room, switch it to have air go up and put
it on the lowest speed. I can do wonders where radiators are concerned and
also are good in the summer when reversed.
Bob77869 <bob7...@aol.com> wrote in message
news:20001006013636...@ng-ci1.aol.com...
Bob77869
would be almost useless. >>
Awe.... you think? You say below that perfectly still air is bad. A tiny 3 inch
fan would do a great job of keeping the air from being perfectly still. And if
there is not much more advantage to having more air flow, then a small fan
should be good enough. No? But, I would try to get maybe a little bigger fan,
like 4" or 5".... The fan on my computer blows quite a bit of air. Not all
computer fans are created equal.
<< The reason a fan would help is that heat transfer (from radiator to air) is
dependant on the difference in temperature. With perfectly still air, a
layer of hot air sits around the radiator. If the radiator is not confined,
that air should rise pulling cold air from the floor.
>>
This makes prefect sense. I was hoping someone would explain the physics, thank
you.
<< The first thing you should do is make sure that there is no restriction of
airflow around, under or over the radiator.
>>
Yeah, thanks, I will do that. In one place my radiator is between a sink
cabinet and the wall. I cant move either one. I wonder if that one will benefit
the most from a fan.
Bob
Bob77869
you can. >>
I do? I dont want a wind in there, its drafy enough as it is. I thought I
wanted just enough to get some air movement over the radiator.
Bob
Bob77869
<< Unless you're installation was grossly screwed up originally, the radiator
should be sized for the room. >>
Well, another issue is that I dont have control over the thermostat. The
thermostat is shared by 3 apartments, and mine is the coldest. This is why I am
taking these measures because these are things I can control. I actually
wouldnt have a problem if I could just turn it up. So, I want to do everything
I can myself before I go bother everyone else about how the thermostat is set
too low for me........
<< I'd make surer it isn't full of air and
consider removing the radiator cover. >>
Yeah, I plan on definitely doing this. From what you said and everything else I
read, Im hopful this will help a lot. And my cover is massive, with only tiny
holes! Im sure it is greatly cutting the heat transfer.
Thanks Dan.
Bob
Marc O'Brien
>
> Hi,
>
> I have an old fashioned hot-water room radiator. I want to increase the
heat
> output into the room. My question is, will it help any to have a fan
blowing
> over the radiator? Say, a very small fan sitting on the floor behind the
> radiator blowing into the room?
>
transfer and
> heat ouput. I read about removing the radiator cover, stripping and
repainting
> with matte black radiator paint, bleeding the radiator periodically,
keeping it
> clean and dusted, and adding radiator reflectors on the floor and walls
behind
> the radiator. However, I have not heard mention of the use of a fan. Why
does
> no one talk about it? A car uses a fan over the radiator. Doesnt it make
sense
> that a fan over a home radiator would increase heat transfer in the same
way as
> a car?
>
> Also, if anyone has any ideas on how to get more output from a radiator, I
> would greatly appreciate it! I dont want to freeze again this winter!
I'm not the expert on hydronic systems, I'm a vapour compression
refrigeration specialist, so my comments may be out of place here. Since I
cannot comment from experience I have to come in from the angle of first
principles and my own intuitive guesses.
It's called a radiator ? Why is it called a radiator and not a heat
exchanger ?
The sensation of warmth is derived 66% from radiated energy and 33%
conducted energy.
This is to say that in a room where the surrounding fabric (walls, floors,
furniture etc.) are at 32F and the air is at 72F the body will sense the
room temperature to be an equivalent to (1/3 of 72) plus (2/3 of 32)
equalling a perceived temperature of 44.88F
Then, on the other hand, if the fabric were 72F and the air 32F the
perceived temperature would be (1/3 of 32) plus (2/3 of 72) equalling 58.08F
So this to me says the radiator and the air surrounding should be permitted
to get as hot as possible. This would require that the air travel very slow
so that it be an extension of the radiator rather than the radiator be a
heat exchanger.
By the above principles, if someone were to tell me their radiator was
warming the room too much and they couldn't reduce the hot water flow
through it nor reduce the water temperature, apart from placing a shield in
front of it, I would suggest fanning it to cool it to reduce it's radiation
power. With the fan, the air warming slightly with the radiator cooling
would probably act to cool the occupants by reducing the perceived
temperature even though the room temperature was rising.
Bob77869
Hi Marc,
"Marc O'Brien" mlob...@fridgetech.fsnet.co.uk wrote:
<< This is to say that in a room where the surrounding fabric (walls, floors,
furniture etc.) are at 32F and the air is at 72F the body will sense the
room temperature to be an equivalent to (1/3 of 72) plus (2/3 of 32)
equalling a perceived temperature of 44.88F
>>
Hmm, but if the air is 72, wont that warm the interior surfaces to nearly 72?
Assuming everything is insulated well enough, wont it be true that the warmer I
make the air, the warmer everything will be? I know things get heated by
ratiation also, but not everything is in a straight shot from the radiator
either. A couch, for example, that is around the corner from the radiator will
only be heated by the air. Right?
<<With the fan, the air warming slightly with the radiator cooling
would probably act to cool the occupants by reducing the perceived
temperature even though the room temperature was rising.>>
Wow, thats quite a conclusion!
A very interesting post Marc. Thanks. Maybe I wont use the fan after all.
Bob
Marc O'Brien
>
> Hi Marc,
>
> "Marc O'Brien" mlob...@fridgetech.fsnet.co.uk wrote:
> << This is to say that in a room where the surrounding fabric (walls,
floors,
> furniture etc.) are at 32F and the air is at 72F the body will sense the
> room temperature to be an equivalent to (1/3 of 72) plus (2/3 of 32)
> equalling a perceived temperature of 44.88F
> >>
>
> Hmm, but if the air is 72, wont that warm the interior surfaces to nearly
72?
That would tend to happen, how close to "happen" would "tend to happen"
get, depends on the relative rates.
> Assuming everything is insulated well enough, wont it be true that the
warmer I
> make the air, the warmer everything will be?
Hmmm, let me see, damn, the more I sit here thinking about this the more
complicated it gets...
I'm wondering, which method aids heat retention more? Radiating an amount at
the bodies in the room or blowing that amount at the bodies in the room.
Which method slows heat loss through the fabric which is exposed to cold.
Heat flow through your insulated walls depends on temperature difference,
blowing at the bodies also increases that heat leaking contributing
temperature difference, I think radiating would be the winner here.
> I know things get heated by
> ratiation also, but not everything is in a straight shot from the radiator
> either. A couch, for example, that is around the corner from the radiator
will
> only be heated by the air. Right?
Yes, around the corner it'll be heated by the air and radiation reflections
and radiation from warming bodies that are in sight of both that couch and
the radiator.
I recon you need to give that radiator a clear view of as much of the room
as possible, let it get as warm as possible.
> <<With the fan, the air warming slightly with the radiator cooling
> would probably act to cool the occupants by reducing the perceived
> temperature even though the room temperature was rising.>>
>
> Wow, thats quite a conclusion!
>
> A very interesting post Marc. Thanks. Maybe I wont use the fan after all.
I'm only going by logic here, I myself would not accept what I say until
experiment proves it.
Bob77869
<< Yes, around the corner it'll be heated by the air and radiation reflections
and radiation from warming bodies that are in sight of both that couch and
the radiator. >>
Oh, okay. I didnt think of that. That makes sense.
<< I recon you need to give that radiator a clear view of as much of the room
as possible, let it get as warm as possible. >>
A good reason not to use a radiator cover like I have!
<< I'm only going by logic here, I myself would not accept what I say until
experiment proves it. >>
Hehe... Okay. Thanks Marc.
Bob
Dan Murphy
Bob77869 wrote:
Grainger has a wonderful low profile squirrel cage with about 300 cfm that
requires only 3 inches of height clearance. Maybe you could conceal that
underneath the radiator if you want something permanent and unobtrusive. Those
dayton fans don't move much air.
RonH
converting 10 small convector's , into forced air convector's. Using small
4" muffin fan's , 5 per unit at 106 cfm's per fan. These unit's temp's are
based on outdoor air temp. I have many question's yet on how well these
will work. They are located by the front entrance, and will get a blast of
cold air each time the door's open and close.
RonH
'
Bob77869 wrote in message <20001006173616...@ng-fi1.aol.com>...
dand...@gmail.com
> Hi,
>
> I have an old fashioned hot-water room radiator. I want to increase the heat
> output into the room. My question is, will it help any to have a fan blowing
> over the radiator? Say, a very small fan sitting on the floor behind the
> radiator blowing into the room?
>
> heat ouput. I read about removing the radiator cover, stripping and repainting
> with matte black radiator paint, bleeding the radiator periodically, keeping it
> clean and dusted, and adding radiator reflectors on the floor and walls behind
> the radiator. However, I have not heard mention of the use of a fan. Why does
> no one talk about it? A car uses a fan over the radiator. Doesnt it make sense
> that a fan over a home radiator would increase heat transfer in the same way as
> a car?
>
> Also, if anyone has any ideas on how to get more output from a radiator, I
> would greatly appreciate it! I dont want to freeze again this winter!
>
>
> Bob
Have the same problem, Radiators with covers (wood in this case - to look like furniture) . I placed small low-velocity PC type cooling fan blowing into cover, In theory, air going in has to come out, It helped to get some of the heated air into the room. I also wired in a toggle switch to turn on/off when I want. You could get real fancy and wire in a thrmo controlled switch. Stay with a low CFM fan, you may get a cooling effect is you blow too much air.
Dan
Wilm., DE
Congoleum Breckenridge
track3...@gmail.com
Has anyone put computer fans behind a radiator yet and found it has worked???
mike
> Hahaha yea probably
>
> Has anyone put computer fans behind a radiator yet and found it has worked???
>
The more air you blow across the radiator, the more energy you get out...
up to the point where you reduce the radiator surface temperature to
that of the incoming air...for an enclosed heat source.
With an open radiator, it' gets a little more complex because there
is actually radiation into the room.
As a practical matter, blow air across it until the output air
isn't much hotter than the input air. If you stay away from
the limiting case, the nitpickers won't have any reason to nitpick,
because the deviation from ideal is in the noise.
Decide ahead of time what you're trying to achieve. In a hvac system,
the cost of moving the air around isn't trivial.
TimR
>
> Decide ahead of time what you're trying to achieve. In a hvac system,
> the cost of moving the air around isn't trivial.