Crawl Space Steam Pipe Insulation

mcvetyty

Hello,

Here is a question I have for you all... I have a kitchen addition with a crawlspace under it. The crawlspace has steam pipes for two radiators running through it.

The wood floor in the the addition has notoriously been cold. Like Freezing cold. Last spring I had it insulated, and that improved it by about 20%, but its still very, very cold.

Would it be completely crazy to UN-insulate the steam pipes down there? My rationale is that maybe if I heat the addition and the crawl space then perhaps it will retain its heat a bit longer and not be so cold.

What would be some potential downsides to this?

KC_Jones

Heat moves to cold. Heat moves to cold more rapidly with a greater Delta T. So most of the heat would tend to move to the coldest thing in the crawl space....which is typically the ground. This will also make those pipes condense at a crazy rate. This would cause the radiators to heat more slowly and most likely cool those rooms down. Then to counteract that you put a larger vent on the radiator to get the heat back into the room. Now with the bigger vent and additional condensate from the uninsulated pipes the vent starts spitting and you come back here asking why the vent is spitting. Not trying to be smart just laying out the whole scenario for you. Uninsulated pipes are generally not a good idea and even if none of the above happened it wouldn't be a good floor warmer. To give you an idea my boiler is under my living room the top of my main pipes, boiler take off pipes going into the header are only about 10" below my floor. I can't feel a thing and those pipes carry all the steam for the whole house. I essentially get zero floor warming because it's all going into the basement....that's where the greater Delta T is.

KC_Jones

I forgot to mention....I like your creative thinking!

mcvetyty

Thanks for the great explanation, and makes sense! Insulation will stay on, and I guess I'll just buy a rug instead.

KC_Jones

I have a room just like you are talking about, except I have a full basement. My problem is there is no heat in the room and it has hardwood floors. It's our laundry room/ half bath. The only heat is a short run of 1" steam pipe that runs halfway across the ceiling for an upstairs radiator. You can feel that pipe as soon as you walk through the door. One of these days when I am really ambitious (and go to some effort to find a radiator) I will add heat to that room.

Fred

Did you have the side walls inside the crawl space insulated with rigid insulation as well? That may reduce the cold floors by another 20%. Those steam pipes that go through there should still give off a little heat, even though they are insulated. If you can insulate the surrounding walls, you may create enough of an envelope to help the floors.

JUGHNE

In this area we strive to insulate the inside surface of exterior walls of crawl space, outside surface would be better. Not the floor above as the crawl space is treated as conditioned space. Of course we have mostly forced air here so that space gets a little heat and cooling (for dehumidification). The crawl space is not vented to the outside today as it was years ago. The insulation job is easier said than done on an existing crawl space. For new the block wall would have 2" foam board placed on the inside surface wall. (No not up to code--not covered by sheetrock---but I'm not doing it and there are always at least 5 smoke detectors installed in new construction). Lately foam concrete forming is used everywhere (the concrete structural part is encased in 2" of extruded foam.) And with your kitchen above there is most likely water lines in this space that we would have to think of here.
Just insulating the rim joist/box joist on top of the concrete/block walls helps a lot. I have worked in crawl spaces in winter and just removing that 3 1/2" batt to drill out or whatever your hands get pretty cold. Air infiltration in that area is also a big heat loss...really noticed when the wind blows and you are laying next to the wall. All of this will make your floor a little warmer, just not as cold. But it reduces the total heat loss of the structure by quite a bit.