Steam Radiator in Poorly Insulated Space

Rmajestic

Hello!

This is our first winter in our house, and we still have a lot to learn about our single pipe steam system. At the back of the house we have a door that leads to a poorly insulated vestibule that’s connected to the basement stairs and a breezeway to the garage. There is a radiator unit on the landing. Yesterday the temps here dipped down to -14 degrees F. When I went to get something in the basement I noticed that it was even colder than usual in that space, and when I touched the radiator it was ice cold. A thermometer out there today shows that the air temp is 20 degrees F inside the vestibule. Can steam radiators freeze? If my radiator has frozen up, what do I do about it? The rest of the system seems to be running well, and we just had someone out to do annual maintenance on the boiler last week. Thank you in advance!

KC_Jones

It's highly unlikely for a steam radiator to freeze, they don't fill with water and on the next cycle the steam would melt any frozen condensate laying in the bottom, if that did happen.

That said, it could be so cold it's condensing before it has a chance to heat. Is the pipe feeding this radiator in the basement insulated? Is it in a space that is similarly cold?

Then there is venting. How is the main venting in the basement? What size vent is on the radiator in question?

ethicalpaul

I would question the value of trying to heat a poorly insulated vestibule. I'd rather that steam went to my living room

Rmajestic

KC_Jones said:

It's highly unlikely for a steam radiator to freeze, they don't fill with water and on the next cycle the steam would melt any frozen condensate laying in the bottom, if that did happen. That said, it could be so cold it's condensing before it has a chance to heat. Is the pipe feeding this radiator in the basement insulated? Is it in a space that is similarly cold? Then there is venting. How is the main venting in the basement? What size vent is on the radiator in question?

The pipe feeding the radiator had asbestos insulation that was recently removed and we haven’t replaced it yet. The ambient temp in the basement is quite warm as the pipes aren’t currently wrapped. No issues with the main vent, it was inspected last week. The vent on the radiator unit is a Dole VariVent 1A, currently set to 4. Like most of the vents in the house, it looks like it’s been on there a while.

KC_Jones

Rmajestic said:

KC_Jones said:

It's highly unlikely for a steam radiator to freeze, they don't fill with water and on the next cycle the steam would melt any frozen condensate laying in the bottom, if that did happen.

That said, it could be so cold it's condensing before it has a chance to heat. Is the pipe feeding this radiator in the basement insulated? Is it in a space that is similarly cold?

Then there is venting. How is the main venting in the basement? What size vent is on the radiator in question?

The pipe feeding the radiator had asbestos insulation that was recently removed and we haven’t replaced it yet. The ambient temp in the basement is quite warm as the pipes aren’t currently wrapped. No issues with the main vent, it was inspected last week. The vent on the radiator unit is a Dole VariVent 1A, currently set to 4. Like most of the vents in the house, it looks like it’s been on there a while.

It does need to work correctly, but the bigger question is what size main vent it is. With 1 pipe steam it's all about the venting. Need to vent the mains fast 5 minutes or less in most cases, and then vent the radiators relatively slow. The goal is to get steam at every radiator before any of them start heating.

The lack of insulation could be a contributing factor, but not a primary factor.

Rmajestic

ethicalpaul said:

I would question the value of trying to heat a poorly insulated vestibule. I'd rather that steam went to my living room

Heard. It looks like the previous owner recently removed some sort of sheet insulation or paneling in that space (it’s a super old, super weird house and that “room” joins several areas that were clearly built and renovated in different eras). The valve knob is missing from the radiator, and we’ve had a lot going on so we’ve just left it the way we found it and haven’t really decided on a long term plan for that part of the house.  Ideally, I would like to store some things in the built-in cabinets out there without them freezing.

Jamie Hall

Oddly, it is possible for a one pipe steam radiator -- or, more likely, the pipe leading to it -- to freeze. It usually won't do much damage, as there isn't that much water involved (it's not like plumbing, or a hot water system). But t does happen. I've had the trap on a two pipe system radiator freeze.

And I think you have pinpointed the problem: "The pipe feeding the radiator had asbestos insulation that was recently removed and we haven’t replaced it yet. "

That'll do it.

dabrakeman

Assuming you have witnessed the radiator previously working it doesn't hurt to just check that your radiator vent isn't frozen and thus not venting. No venting = no steam. Run a cycle after being sure it is venting. If that is not the problem then do as Jamie says.

The Steam Whisperer

The lack of pipe insulation could be the primary factor if the boiler is close to the right size. All that heat going into the basement used to be delivered to the radiators. I have had a number of buildings where we replaced the steam boiler with a correctly sized model, but some radiators would not heat until the steam piping system was insulated. After insulation, no problems.

delcrossv

Sure the valve is all the way open? Might want to run a cycle with the vent out just to make sure the vent hasn't failed and/or the supply valve is open.