Insulating Heating System Pipes
mwkofcwc
| Posted in Energy, Heating & Insulation on
I want to insulate the supply and return pipes on my oil fired heating system (hot water to cast iron radiators) and have the following questions:
1. Should I use fiberglass insulation or one of the other available materials like polyethylene?
2. What thickness should I use? I can find fiberglass in 1/2″ to 2″ thicknesses and polyethylene in 3/8″, 1/2″ and 3/4″. Of course it gets more expensive as it gets thicker so I’m wondering if the extra investment now will pay for itself later.
3. How close to the boiler should I bring the insualtion? The boiler was new last winter, so it’s fairly well insulated itself. Should I bring the insulation right up to the boiler jacket?
I appreciate any help or opinions anyone can offer.
Replies
I'm not in the business, but have a NG-fired heater in my basement. There is 2" of fiberglass on the supply & return, including a this (foil?) jacket. The insulation goes to within a couple of feet of the heater. This stuff appears to have been installed fairly recently. I bought the place a year ago and the heater is 2 years old.
The lady who owned the place before me spent some extra money on a couple of things to reduce energy consumption (automated flue damper, reasonably efficient furnace, flourescant replacement bulbs for standard fixtures), so she may have been willing to pay a little extra for thicker insulation.
An interesting side note on insulation, although I doubt that it pertains in this case: There are diminishing returns once you pass a critical thickness when adding insulation to pipes. Once it gets so thick, the extra surface area overcomes the decreased heat flux. At least that's what the textbooks say...
What are you insulating them from? You won't save any money because the heat that leaks out goes into the house anyway. It would only be worthwhile if you ran the pipes through a cold area, or had a really long run (where the heat loss would make the fluid too cold by the time it got to the intended space), or had a safety concern where someone could contact the pipe.
I doubt that polyethylene could take the heat, but the manufacturer's specs would spell that out.
I have to strongly disagree with you. Heating pipes in a basement should always be insulated. The thinking that the heat will eventually make its way up to the living space is absurd. Yes a small portion of the heat will but YOU want to stay warm not the crap you store in the basement.
The guys at http://www.heatinghelp.com will agree with me 100%
Edited 9/19/2005 7:26 pm ET by reinvent
Though I wasn't explicit, I was speaking of pipes going through living spaces, basements included. If a basement is a cold storage space then insulating it is worthwhile.
Thanks for your responses.
The reason I want to insulate is that in the winter the basement is often warmer than the living areas of the house. I want the heat upstairs where I live.
The foundation of our house is a stone which leaks during heavy rain so while we use the basement for laundry and shop space, it doesn't need to be much warmer than 55 degrees. If I do need to be down there for an extended period, there is a heating unit in the basement. It's basically a box with a fan blowing across some finned copper pipe. This contraption is on it's own loop.
Anyway, I think the consensus is use the thickest possible fiberglass insulation and cover all the pipe. Is that it?
Yours is a good situation where insulation would be beneficial. Fiberglass is definitely the way to go. Probably 1" is plenty thick for insulating against 55°. I wouldn't go thicker unless the cost is very little more. You are better off to get something on every exposed part you can reach rather than going thicker in fewer areas.
Just curious, and not to hijack the thread here, but is the major heat loss from the hw pipes convection (which FG insulation would ameliorate) or radiation (which would benefit from some other fix)?
I would recommend the FG pipe insul. It gives better performance and looks more professional. Insulate every sq in of pipe you can get your hands on.
1" fiberglass, with a basic all-purpose paper service jacket is the recommended insulation. Johns-Manville
http://www.jm.com/insulation/performance_materials/products/ci34_microlok.pdf
makes a product that is ideal for this application and is available at most plumbing supply houses. The cheap foam junk available at the home centers is adequate only for domestic water pipes.