Single-pipe steam heat for very small room

orick

My 1870s house has single-pipe steam running off of a Weil-McLane boiler. I've been really happy with the steam heat (quiet, consistent, and no air blowing around).

My house has a very small bathroom underneath the stairs leading to the second floor. There is no heat source for the bathroom, and it gets very cold in the winter because it's on an exterior wall.

What's my best option for heating this bathroom?

There are steam pipes in the cellar within a few feet of the bathroom, so it would be easy to run a steam pipe through the floor. But even the smallest cast iron radiator (that I've found, anyways) would be too big for this bathroom, both in terms of fit and in terms of heat output.

If I just want to add a little bit of heat, can I just run a black iron pipe through the floor and cap it? Would that be pointless? Is there some kind of tiny radiator I could install?

Thanks for any ideas.

ethicalpaul

There are small ones that go inside the wall and there are also wall mounted ones.

Are you sure the smallest you found won't fit? They make them pretty small! And are you sure it wouldn't provide enough heat? They put out a good amount of heat for a tiny room.

You can do the pipe, but don't cap it. Instead put a radiator vent on the top of it. This is not unheard of but it would provide less heat than any radiator I think.

You could run the pipe up to a strong shelf with a small radiator on it although a lot of the heat would go up and not warm your feet.

You could also do a radiant loop off of your steam boiler.

orick

Thanks for your reply!

ethicalpaul said:

Are you sure the smallest you found won't fit? They make them pretty small! And are you sure it wouldn't provide enough heat? They put out a good amount of heat for a tiny room.

The smallest I found I think would put out too much heat. E.g., the Burnham slenderized 4X19X4, which is rated for 1,536 BTU with steam. The room is only about 20 sf with a low ceiling.

I have not seen any very small wall steam radiators. If you have any in mind, please point me in the right direction.

ethicalpaul said:

You can do the pipe, but don't cap it. Instead put a radiator vent on the top of it. This is not unheard of but it would provide less heat than any radiator I think.

This is along the lines of what I was thinking. I'm just wondering if the heat output would be enough to make a difference (I don't need it toasty, but taking the edge off the cold would be good).

ethicalpaul said:

You could also do a radiant loop off of your steam boiler.

A hot water loop is probably a good solution, but I am hoping to find a more economical option.

Jamie Hall

You can check to see if the pipe idea would work. Pipes have an EDR, too, just like radiators! It's the surface area of the pipe -- so take the circumference, multiply times pi -- 3.14 -- divide by 12 to get feet, and multiply by the length of pipe in feet. That will be the EDR. Say you have a pipe with a 2 inch diameter. That would be about 2 square feet for a 7 foot tall pipe. 500 BTUh? Might be enough. What's the exterior wall area?

ethicalpaul

Ahh OK I misread your original post regarding your concern about the heat output. You can always cover some or all of it with something to limit the heat. That 4x19x4 is very small, I have one like it.

here is the in-wall kind. I pulled one very much like this out of my bathroom prior to installing a new radiant floor: https://images.app.goo.gl/ZRd5r3znrnpuwfyg7

orick

Jamie Hall said:

What's the exterior wall area?

The exterior wall area is about 32 sf. Very helpful math, thank you!

orick

ethicalpaul said:

Ahh OK I misread your original post regarding your concern about the heat output. You can always cover some or all of it with something to limit the heat. That 4x19x4 is very small, I have one like it.

here is the in-wall kind. I pulled one very much like this out of my bathroom prior to installing a new radiant floor: https://images.app.goo.gl/ZRd5r3znrnpuwfyg7

You got me thinking about putting a little radiator behind the toilet, in the unused space beneath the first few steps (a good solution, but lots of work). The photo below is not my house, but gives you an idea of the layout. (The sink is inside the door to the left. If I run a pipe through the floor, the easiest place to bring it up would be under the sink.)

ethicalpaul

Yeah, that would be good. Maybe under the sink too if you have or can get a small attached-to-the-wall kind

Jamie Hall

32 square feet? No windows? If we are a bit pessimistic and assume an R value of 4 for that, then you're looking for 8 BTUh per degree of difference between inside and outside. If your outside design is 0 and you want the occupants cosy, say at 70 -- then you really only need around 600 BTUh max...

KC_Jones

This was a custom solution by one of the pros on this site. Post 5 in this thread.

https://forum.heatinghelp.com/discussion/151994/new-steam-mini-tube-installation-in-ohio/p1

Steamhead

orick said:

You got me thinking about putting a little radiator behind the toilet, in the unused space beneath the first few steps (a good solution, but lots of work).

You don't want to put the radiator behind the toilet.

Remember the sign that says "We aim to please- you aim too, please"?

Not everyone does

Hap_Hazzard

If you can find an old junk radiator you can remove everything except the first and last section an end up with a tall, narrow radiator that would fit in any corner. Don't even bother with a valve; just stick a street elbow in the supply end and run a riser into it.

If you can't find a used one, Castrads makes an 18" 2-column, 4-section radiator that's only 4 EDR.

https://www.castrads.com/us/product/mercury-2-column-18in-4-sections/

Hap_Hazzard

The trouble with using pipe to heat the space is that steel pipe doesn't hold heat as long as cast iron radiators, so it will still be cold in there between heating cycles.

Phil53

I think a 2 Ft. piece of CI baseboard would work well. Just vent and pitch it a little.

Hap_Hazzard

True. It doesn't stick out much and it retains heat well. With the ease of access he could even run separate supply and return lines if he needed to.

Gsmith

Cast iron baseboard should work fine, I have it in my one bathroom. Just pitch it well and use a good vent.

orick

Thanks everyone for the ideas.

If I go with a baseboard, I think I could run a separate return line. Are there good alternatives to the Baseray (or is that a solid option)? https://www.usboiler.net/product/baseray-baseboard-radiator.html

Hap_Hazzard said:

If you can find an old junk radiator you can remove everything except the first and last section an end up with a tall, narrow radiator that would fit in any corner. Don't even bother with a valve; just stick a street elbow in the supply end and run a riser into it.

I did not realize that was a possibility. Will the sections really come apart? Aren't they welded together? How would I attach the first/last sections together?

Hap_Hazzard said:

If you can't find a used one, Castrads makes an 18" 2-column, 4-section radiator that's only 4 EDR.

https://www.castrads.com/us/product/mercury-2-column-18in-4-sections/

Thanks--that would be really nice, but blows up my budget. It looks like there are lots of good options for economical small two-column radiators in the U.K., but not so much here in the U.S.

orick

orick said:

I did not realize that was a possibility. Will the sections really come apart? Aren't they welded together? How would I attach the first/last sections together?

Looks like others have been down this road before.

https://www.youtube.com/watch?v=6rPADasYq70

This could be a really neat project. But after it all I would probably wish I just bought the smallest Burnham slenderized and installed it with a stingy vent.

coelcanth

i think you would be very comfortable with a 2" black iron pipe riser-radiator because my 1920's house has this exact arrangement in its two bathrooms.

the steam supply runout under the floor is smaller, but the simple 2" pipe in the corner runs almost the full 9 feet of the bathroom with a cap just below the ceiling. side of the pipe is tapped for a regular 1/8" angle air vent. i use a Hoffman 40.

JUGHNE

Have you considered a small electric heater?
A wall mounted cove heater is up and out of the way.
Wall tstat is recommended versus unit mounted type.


I have a 1/2 bath, 5X5, fortunately no exterior walls. It has a 4 bulb wall light. 240 watts heat it well. I turn the lights on a few minutes before a comfortable reading session......

orick

coelcanth said:

i think you would be very comfortable with a 2" black iron pipe riser-radiator because my 1920's house has this exact arrangement in its two bathrooms.

the steam supply runout under the floor is smaller, but the simple 2" pipe in the corner runs almost the full 9 feet of the bathroom with a cap just below the ceiling. side of the pipe is tapped for a regular 1/8" angle air vent. i use a Hoffman 40.

Thank you! I am seriously considering this, especially in light of your endorsement.

EBEBRATT-Ed

@orick I think the 2" pipe would be fine. If you need more heat than that you could use a piece of steel fin tube mounted vertically and build an enclosure around it with expanded metal and wood (like a radiator enclosure).

As I recall @gerry gill made a welded radiator if you search his posts

ChicagoCooperator

Adding another voice to the go ahead with the pipe: grew up in an apartment where the smaller bathroom had a 2 or 2-1/2" pipe with vent (we were on the top floor) for heat with two outside walls and a leaky window and it was mostly fine.