Insulating Behind Steam Radiators

NY2024

Hi all:

I have two small steam radiators in the entryway to my 1924 semi-detached townhouse. The entryway sits over a crawlspace (not over the foundation). Last year, we had the crawl space encapsulated with a vapor barrier and thick spray foam along the walls and joists, which definitely made a difference in the overall comfort of the entryway (i.e., the floor is not ice cold any longer).

This year, I'm trying to locate areas of air leakage throughout the house and seal them with caulk / foam gaskets / spray foam, etc.

Behind/below the two small steam radiators (which are normally covered by metal radiator enclosures), there are big gaps between the floor boards and the drywall. These gaps allow a tremendous amount of cold air into the entryway. On cold days, when the radiators aren't steaming, you can really feel the draft coming in from those locations.

I was wondering if you had any good ideas about how to seal up this gap area behind the radiators, and how to seal behind baseboard trim in general. In a number of rooms, I can feel the cold air coming in through the gaps between the baseboard and floorboards.

Thank you!

EBEBRATT-Ed

It looks like with remodeling etc that there is not enough room behind the radiators for for the wooden baseboards.

I don't know what caused that issue. Maybe the wall was covered with additional drywall??

The right fix is to disconnect the rads and have the pipes moved so the rad can be pulled out from the wall a few inches.

Other than that you could pull the rad out and seal the openings, but I am afraid it wouldn't look very good

pecmsg

Fiberglass

Foam board

Spray foam

Newspaper

ethicalpaul

I'd shoot Great Stuff foam down there to seal it then figure out what to do about the trim. As @EBEBRATT-Ed said, they apparently left it out because there wasn't enough room. Did they say what their plan was? I see the flooring is also cut away to avoid interference with the radiator, but that's probably not related to your draftiness.

EBEBRATT-Ed

@ethicalpaul

I had a space like that where the wall meets the floor in my house I used to own. The draft that was there was unreal. Lived with it for years. The kitchen was always cold. Unfortunately, it was behind the kitchen cabinets. When I finally got around to remodeling, I could see where all the air was coming from. Spray foamed it all and sliced it off flat. It was all hidden buy the new floor and the new cabinets.

bburd

@NY2024 does that area heat well? If the system is steam, the air vent is in the wrong location and will close long before the radiator is thoroughly heated.

For steam, the air vent should be 1/3 to 1/2 way up from the bottom on the side opposite the supply pipe. There should be a plugged boss in that location.

The upper vent location is for hot water systems.

Waher

havelock wool, foam is a bad idea next to steam because of the high temperature leading to off gassing.

as others have said the air vent is in the wrong location for a steam radiator

https://havelockwool.com/collections/store/products/havelock-wool-window-and-door-insulation

NY2024

Thank you very much for the suggestions! I'd never heard of the Havelock wool insulation. I'll look into that more. I share your concerns regarding potential off-gassing regarding spray foam near a steam radiator.

The radiator unfortunately is far too close to the wall, but adjusting its location would involve some re-piping work which probably isn't in the cards at this time.

This radiator is covered by a metal enclosure (which I removed for the photos), so you don't see the gap behind it on a daily basis. However, you can feel the cold draft coming in.

I would like to be able to place the air vent lower down on the radiator, but there's no room between the radiator and the wall to drill out the plug and put the air vent in the right place. Perhaps in the off season, the radiator can be removed from the wall and the air vent can be placed in the correct location. The radiator heats up well though regardless.

pecmsg

You can tap at the right spot and pipe up to the vent.

Larry Weingarten

Hi, You had the crawl space encapsulated. Were the vents also sealed?

Yours, Larry

TheUpNorthState88

Since this is covered by a radiator cover normally, I would just stuff pink fiberglass insulation until fully blocked. They sell the unfaced variety at Home Depot in small bundles meant for small jobs like this. No spray foam next to a radiator. Not because of fire risk but off gassing risk.

RTW

Just an observation:

Dont know why many comments advocate buying products from corporate Big Box stores rather than local family owned hardware/lumber/plumbing and electrical stores with credible advice etc,. Guess I must be old fashioned

Regards,

RTW

AdmiralYoda

For those saying to avoid spray foam near the radiator due to the heat resulting in off-gassing….

Not that I disagree with spray foam off-gassing when exposed to heat….but won't the gap between the floor and the baseboard be relatively cool?

Even if the enclosure gets pretty hot I suspect that area will remain cool-ish as the fresh air comes in from the bottom. Food for thought as this probably would have been my approach.

You could use spray-foam and then cut it flush with the floor and wall and then install a narrow wooden strip of wood (like 1/4") to cover up the foam maybe?

My next thought would be to just pack it full of fiberglass and call it a day.