Which Insulation for Steam Pipes in Existing Wall Voids?

Billy_13

Hello All.
In honor of Columbus Day, I want to insulate the steam and condensate lines inside my existing wall cavities/wall studs. Currently, there is no insulation on any of these pipes inside the walls. Just air. Looking at 8-9 wall cavities to insulate. Some even go from basement up to 3rd floor bedrooms (Victorian home built 1899).
*I insulated all my exposed steam/condensate lines 2 years ago and $$$ savings was huge*

Being the steam pipes reach 212F, what are my options? I hear conflicting information on Spray Foam.

Also, I would prefer not to open up every wall cavity, if possible. Is there a "blown insulation" option I can use?

Thanks!

leonz

I would check with an insulation contractor about blown fiberglass insulation for the wall cavities.

The contractor would drill large diameter holes into the walls using a large diameter hole saw to blow the insulation into and then put the plugs back in and then plaster over them if you have good hand laid plaster.

If you have the room perhaps cutting a large rectangle out of the wall on each floor wide enough to fill the left, center and right sides of the twin steam pipes in the open cavity filling it from left to right by lowering the hose into the pipe cavity and raising the filler hose until the insulation reaches the rectangular cut out and then moving to the upper floor to start again after the rectangular piece cut from the wall is replaced. Plastering if needed would be done after the hole is sealed with some lath and chicken wire to support the plaster.

The contractor would have to refill the wall on the top floor as the insulation will settle and that could be done on the third floor.more than once as the insulation would continue settle.

They would have to have a shop vac running all the time near the filling hole if a rectangular cut out is made to ride herd over the insulation and to keep it from blowing all over as it fills the three spaces in the wall cavity.

Short of breaking the portion of the wall out where the vertical riser pipes are and then stuffing R 24 ceiling fiberglass batts behind the pipe on each floor from the floor to the ceiling is the other option.

FriendlyFred

If you have access to the wall cavities, but not the entire length of the pipe itself, I suppose you could fill it with blown-in fiberglass insulation.

From attic access, use a hole saw to gain access to the wall cavity. If this isn't an option, you could also open up the wall through the plaster, then patch. Feed the fiberglass blower hose either down into the wall cavity as far as you can, then flip the switch. Use something to plug the bottom of the wall cavity to make sure the insulation doesn't fill your basement. Pouring "shake 'n rake" style vermiculite into the cavity is also feasible.

You probably will run into challenges with unknown obstructions, knob & tube wiring, insulation snagging on plaster keys, and pipe penetrations going between floors. A hot pipes and a thermal camera would be an excellent way to see how well your insulation job worked, and where your gaps/voids are located. I have a 'Seek Thermal' that is lowish-cost, and can definitely see where hot pipes are within the wall.

Fred

Are these all exterior wall cavities? If they are interior cavities, I would think most of the heat emitted by those pipes is not lost but is also helping to warm the interior living spaces in the house.

ChrisJ

Fred said:

Are these all exterior wall cavities? If they are interior cavities, I would think most of the heat emitted by those pipes is not lost but is also helping to warm the interior living spaces in the house.

The same can be said about steam piping in anyone's basement or in a crawlspace under a heated space. The heat rises.

If it's in a wall, I'd probably use normal fiberglass batts, just loosely fill around the pipe. If you don't want to open any of the walls, I agree with others regarding a blown solution but be careful when it comes to what else is in those walls,

For example K&T wiring cannot be insulated around.

Jamie Hall

And as has been implied, but not explicitly stated -- spray foam is out. It will degrade very quickly with the steam heat, and may even become a real hazard.

If these are outside walls, I'd go with the blown in fiberglass (not cellulose). If you are positive you do not have knob and tube wiring. And if I wanted to do it at all; the return on investment after you get done patching the plaster may be pretty marginal. If these are inside walls, I wouldn't bother at all.