How should I insulate the pipes leading from our boiler to the steam radiators upstairs?

September 14, 2004 1:51 PM

Last year we had all the asbestos removed from the basement of our house. Most of it was on the pipes that lead from our boiler to the steam radiators upstairs. I'm thinking I should replace the old insulation. [more downstairs]

The outgoing pipes are about 2 1/8" diameter and the return pipes are 1 1/4" diameter. The guys at Home Depot said I would need to use the more expensive fiberglass insulation because of the heat.
1. How thick should the insulation be? 1 inch thick? 2? more?
2. Should I use the kind where you wrap the stuff around and around and then wrap duct tape over that - or should I go with the preformed kind?
3. On the smaller return lines can I get away with the cheaper plastic foam insulation? Or should I use fiberglass for everything?
4. Home Depot doesn't carry the preformed stuff for the larger pipes. Where can I get that stuff if that's what I should get?

posted by ssmith to Home & Garden (4 answers total)

Around Portland, Oregon, there's an entity (perhaps a joint effort from the utility companies) called the Energy Trust. This organization will, at no cost or obligation, send somebody out to perform an "energy audit" on your home, providing recommendations for improved insulation and energy efficiency, and even suggesting measures that might provide tax credits or rebates.

I don't know where you live, but you might try to find a similar organization wherever you are. Perhaps your local government's energy association might have info. Better still, contact your utilities.

My wife and I were quite pleased with the results of our audit when we bought our new (old) house. The auditor made a number of suggestions, though none of them involved insulating water pipes. (Probably because we don't have a boiler, etc.) She told us where to insulate, and how. She told us what kind of furnace would be best for our home. She gave us advice on lighting. This sounds like the kind of advice you're looking for, except you want to know about your boiler, etc.

Good luck! It's a shame that questions like this don't get more responses. However, I find that the quality of responses on home ownership questions is usually quite high. :)
posted by jdroth at 7:22 PM on September 14, 2004

Response by poster: Thank you jdroth - that's a great suggestion.

AxeMe is a fickle beast. Sometimes you get a ton of responses to the smallest thing, other times bupkis. It's still one of the best resources I've ever used on the net.
posted by ssmith at 6:01 AM on September 15, 2004

The reason you want to insulate your pipes is not for energy effeciency but so that your radiators are getting the temperature of water/steam they were designed for and so you don't return water that is too cold for your boiler.

This is especially important if you have steam radiators or your boiler is of marginal size.

Most plumbing and heating supply places will carry the correct material in all the sizes you'll need. You may have to shop around for a dealer who will sell to someone without an account but there are lots of contractors who have such bad credit they deal with suppliers on a cash basis. Bring actual cash, some places won't take plastic. You want a post installation split style of insulation. The kind I like when I was doing central A/C systems had a self adhesive strip that sealed the split. That was for low temp applications though so it may not be applicable to your situation.
posted by Mitheral at 7:49 AM on September 15, 2004

After re-reading your question, I realize this link about insulating air ducts isn't really applicable but I found it useful so I thought I'd put it up.
posted by jacobsee at 8:30 AM on September 15, 2004