Insulating old recessed convectors
Sublux
| Posted in Energy, Heating & Insulation on
I have recessed convector radiators with only a thin layer of plaster behind them against the outer sheathing. I want to air seal and insulate it somewhat. I think that replacing the plasterboard with polyisocyanurate or some other rigid foam might not be up to code and I don’t want to replumb the radiators to bring them out into the room. Are there any other options?
Replies
Air. The only insulation....sometimes?
More than 50% of the heat you are paying for is being wasted through the wall.
The only way to stop that loss is, to fit insulation behind the radiator.
All generally available insulation works the same way, tiny bubbles of air, trapped or loose in some product or another.
The best insulators are all man made, and of these the sheet materials like polystyrene, polyurethane are widely available and the easiest to use. But, they only slow the loss of heat, they don't stop it. To get the best result you need thickness, and this means 6 or more inches of polystyrene.10 inches will make a difference.
So there you have it....the only insulation better than air is a vacuum, some commercial firms are making vacuum insulation for industry. Possibly if you can weld, you can make your own vacuum panels.
There are only a couple options for rigid foam that can be installed uncovered by GWB. Unfortunately, they are so expensive that its a special order item and you can't just order one or two sheets. So now I'm thinking about getting rid of them all together. I don't know how to evaluate the merits of switching to hot water baseboard because I don't know how much more efficient a distribution system it would be compared to the convectors I have now. Obviously, part of the equation is that I would be able to insulate the recesses and close them up. Any thoughts on hot water distribution systems? There is a ton of info about the most efficient boilers but not nearly as much about distribution...
In theory a sheet metal backing plate behind the units would help, even without additional insulation. If you could space it away from the plaster by a half-inch or so, so much the better, and form it at the top and sides to both prevent air leaks and reflect into the room (by angling the sides and top slightly).