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I lived all my life with forced air heating and cooling, but my house now has steam radiators. They perform ok, I suppose, but I know from trying that just letting the convection cause the airflow leaves them very inefficient.

With a small 6 inch fan blowing at low speed on a radiator, the room temperature will go up 5-10 degrees F.

I would prefer not to have to run power and fans to every rad in the house. I was wondering what the options were for fans to improve the radiators performance.

Standard round fans are the wrong shape, and only target a small portion of the radiator surface.

I would love something that could draw power from the heat difference, since all it needs is low speed fans to move air better than convection does.

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6 Answers 6

An alternative that might work in some rooms is a ceiling fan that has a low speed (we have some 6-speed models in our home where the lowest speed just circulates the air slightly). This would help move air around in the room (and thereby helping to move some heat away from the radiators) and has the added plus that you can use it on higher speeds for summer cooling.

We have forced hot air heat, and our master and living room have high ceilings, so we run the fans year-round.

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All the bed rooms have ceiling fans, 3 speeds, and the slowest speed is not too bad, but the downstairs (Working from home today) has no fans. –  geoffc Jan 5 '12 at 3:17
    
ceiling fans are a great option. You can reverse them each season and definitely help even out the temp in a home. –  DA01 Jun 24 '13 at 0:10

I saw some small heat-powered fans for wood stoves in a Lehman's catalog a few years ago. I'm not sure if a radiator would put out enough heat to spin one.

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Found the Lehmans reference and they have big wood stove ones for $100 and up which is more than I wanted to spend. You would think this would be a more common request? –  geoffc Jan 5 '12 at 0:11

you could make a sterling engine that powers a little crossflow fan and a shroud that guides the airflow

but sterling engines don't start easily, powering the fan (or starting the sterling) from the flow in the pipe might be more reliable

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The best thing you could do is build a radiator cover (see the following This Old House article How To Build A Radiator Cover). The key component to the cover is the reflective material used behind the radiator which reflects the heat back into the room as opposed to being absorbed by the wall as waste. You could, of course, just fabricate a simple backing to the radiator as opposed to creating the entire cover.

A second option is to tile the wall behind the radiator as opposed to placing a metallic material behind the radiator. This might look better than a metallic material in some rooms such as a bathroom.

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Thanks Evan. Already have the reflective material behind all of them. I still think increasing air flow is the key. –  geoffc Jun 24 '13 at 0:43
    
in that case, have you thought about utilizing computer case fans? the largest "standard" size is 120mm still i believe, which is just shy of 5 inches. –  Evan Jun 24 '13 at 1:04

From what I've read and experienced with household radiators: Building a cover over a radiator, according to everything I can find about radiator efficiency, will absolutely decrease efficiency about 30%. This is true even if reflective material is added. Radiator shelves and enclosures were often meant for this purpose - to control an oversized radiator.
A radiator is most efficient when air can flow through it unobstructed, and even more so when the air that flows through it is the coldest in the space. That is why radiators are ideally placed near entrances and windows.

Fans are the answer for increased efficiency and a simple box fan can make a HUGE difference in room temperature. I find that blowing the fan into the radiator, such that air also makes contact with the wall behind, is more effective that sucking air through it. Adding box fans to my current house radiators last winter literally cut my heating bill in half, and kept my house evenly warm.

I am also looking for a quieter solution including 400mm computer cooling fans. Would love to hear ideas from others.

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There is a pretty new product in the UK market at least, which is a radiator fan unit. It does need a power source but it has a built in thermostat so it only turns on when the radiator gets hot. Seems to be quite effective, we have one and it made a real difference to our living room. Not sure if they are in any stores or anything yet but we just got ours direct from their website. It's called a RadFan. Basically blows the warm air from the radiators into the middle of the room instead of going up to the ceiling or out of the window.

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