radiator insulation

Old 01-21-09, 03:48 PM
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radiator insulation

I live in a house built in the 1930's that has the steam radiators built into the exterior walls. I just finished insulating the backside of the radiators with reflectice foil bubble insulation. I think this will help since I do not know how much (if any) insulation was installed at these locations by the builder. My guess is there is probably none since energy was so cheap back then.
I have some of this reflective foil left over and was thinking it might make sense to install some on the inside of the front radiator covers. The covers are heavy gage metal with vent holes at the top and bottom only. Since I am paying to heat the air and not the cover, does it make sense to reflect some of the heat back across the airspace back to the radiator? Sort of like a chimney effect. Does this make sense or am I wasting my time?
Old 01-21-09, 06:27 PM
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Hi Frank, and welcome to the forum. Here is my opinion. Radiators serve two purposes, one to heat the air as mentioned and two, to directly radiate heat across an open space and heat the objects on the other side. I have always questioned why baseboard HW units are white. Black or any darker color does a much better job of radiating heat. To place the foil reflector where you suggest, would reduce the heat absorbed by the cabinet and reduce the radiant distribution of heat. It might also increase the heat loss to the wall behind the cabinet.

As an inexpensive way to direct more heat into a room and away from the cold walls, I have recommended that foil be placed behind the radiator, between it and the wall. The foil/bubble material you are using works well as it provides a foil surface and an air gap.

I hope this helped,
Old 01-23-09, 06:03 PM
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Radiator Heat Reflectors

If I'm understanding correctly you have already put bubble foil between the wall and the radiator. As for adding foil to the inside of the radiator front cover, I think that would be a waste of time and could (as mentioned) send the radiant heat the wrong way (back toward the outside wall).

It's okay that the front cover gets hot. That heat will be transferred to the room, through convection. It's not lost heat.

BTW: Here's how I build my steam radiator heat reflectors, with pictures and the story if anyone is interested. I did quite a bit of research into the subject of radiator reflectors.

Old 01-27-09, 10:47 AM
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Insulation behind radiators

Hello all,

Thanks Peter for the informative site - will be researching more. Our situation is much like the original post - our radiators are actually recessed into the wall. With some gymnastic peeking we can see that nothing is between the radiator and the exterior masonry. We think is it is worth the effort to move the radiator and insulate behind it... Just curious as to the best material to use - a) the reflective foil type or b) the closed-cell rigid panels.

I think it is probable that when we move the radiators, we will find the wall cavity is open around the radiator - should we close things up?

BTW - what do you think of a quick fix of "Great Stuff" foam into the spaces we can reach without moving the beast.

Thanks for any help

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