getting to know my new 1930 single pipe system

tacoma1930 · February 3

Hi folks,
My wife and I just moved into our first house, a 1930 colonial in Boston. It's single pipe steam with an oil-fired boiler (installed in 2021) and 7 radiators (front hall, living room, dining room, and 3 bedrooms and a bathroom on the second floor).

When we moved in, we were getting other plumbing work done and the plumber replaced all of the radiator air vents and at least one leaky valve as part of his once-over of our system. The system was losing lots of water (the low-water shutoff triggered twice in 2 days) but that has stabilized.

The system seems fairly functional from a sound perspective - there is some slight hissing at the living room radiator, but no knocking. From a heating perspective, the issue is that the second floor is significantly warmer than the first. I'm not sure if it's just layout/insulation or something else - each bedroom is significantly smaller than the much more open first floor living/dining space so the rads are maybe just more efficient/effective up there? But I'm waking up sweaty while the downstairs feels chilly.

I've just finished Dan Holohan's "we got steam heat" and am waiting for Lost Art to arrive in the mail. The other potential concern I'm having is the size of my main vent. Picture attached. It looks smaller than I was expecting based on my reading of the book. Other possible DIY-friendly interventions on my list are insulating the basement pipes and possibly installing a TRV in the bedroom. I'm not sure if any of that would help the hot-bedroom issue.

The oil company installed the boiler in 2021 and they're coming in a couple weeks for an included annual service.

Photos (with apologies for the lighting) of the near-boiler piping and the small-seeming-to-me main vent.

ethicalpaul · February 3

He didn't replace that ancient and probably failed main vent? that's weird.

There shouldn't be any hissing anywhere, it is a sign of high steam pressure, and is exacerbated by your probably bad main vent.

Send pics of your new radiator vents, I wonder what he put on there.

Your near boiler piping seems OK from that one pic.

Hopefully your water use goes down to like a gallon per month or less rather than a gallon every couple days.

I recommend monitoring your water level yourself and filling it yourself so you know how much it's using rather than relying on the autofeeder.

bburd · February 3

The overheated upstairs bedrooms are most likely a balancing problem, which on one pipe steam means the venting rate. If you can speed up the venting downstairs and slow it down upstairs that should help.

And yes, that main vent should probably be changed for a Gorton number two.

Steamhead · February 3

@tacoma1930 , you don't mention the kitchen. I bet there was a radiator in there and some Beavis & Butt-Head remodeler took it out. That could certainly throw off the system balance. Check the basement under the kitchen and see if you can find a capped-off tee or pipe, which would confirm this.

Are there any other rooms without radiators?

And, what @bburd said about the main vent. How long is that steam main, and what pipe size? And is it the only steam main in the house?

tacoma1930 · February 3

The kitchen has been remodeled. It has an electric baseboard now. I’ll go pipe hunting today.

Also like a complete dummy I forgot
to mention that 2 of the 3 downstairs radiators have covers on them…. That would certainly affect their effectiveness

delcrossv · February 4

ethicalpaul said:
He didn't replace that ancient and probably failed main vent? that's weird.

........

Wouldn't be the first time. MIL's 4 flat had Dole's from the 1950's (both long failed closed)

SgtMaj · February 4

I would replace the main vent along with setting the pressuretrol to its lowest setting. Any air you hear should be less than a whisper or non existent. Pictures of your radiators depicting size and vent type would also be helpful.

EBEBRATT-Ed · February 4

The radiator covers are reducing the heat output.

tacoma1930 · February 5

Here are photos of the upstairs rads. The plumber didn't mention what type/size vent he was putting in when he replaced them but I'll ask. I know he had to re-thread at least one of the rads.

I cranked the pressuretrol down and that helped with the noise. I may pull the covers off downstairs and pop them on the upstairs ones (if they fit) to cool it all down.

Is replacing the main vent more complicated than it seems? I'm not the most handy DIYer but I can turn a wrench, swap an outlet, that kind of thing.

STEAM DOCTOR · February 5

Not sure if you mentioned this. There's a difference between a heating system imbalance and a room imbalance. Heating system could be totally balanced, but if there are drafts in one area for example, that area will be colder. Shut down the heat and let things cool down for a while. Then jack up the heat and walk around the radiators and time how long it takes each of them to get hot. The radiator should all be getting hot more or less at the same time.

And agree with all of the suggestions above by the way. Replace that main vent. The radiator covers, assuming they do not have openings on top, will greatly reduce heat output to the room. Might be nice and cozy inside the box.

ethicalpaul · February 5

That looks like a no-name radiator vent that I personally would never install. You might as well start to become a steam expert because your guy definitely isn't one. Look at Maid O Mist or Gorton at supplyhouse. The sizes you should look at would be #4 (the default), or #5 or #6 (for rooms where you want more heat due to them feeling cold to you)

https://www.supplyhouse.com/Jacobus-Maid-O-Mist-J4-4-1-8-Angle-Air-Valve-3564000-p

The main vent is easy. Give this one a try: https://www.supplyhouse.com/Jacobus-Maid-O-Mist-J1-1-3-4-x-1-2-Main-Vent-Valve-3563000-p

It has a female 1/2" NPT connection and also a 3/4" male NPT connection. You can find any needed adaptor fittings also at supplyhouse

tacoma1930 · February 5

This is super helpful, and what I'm trying to isolate. If the system is heating evenly in terms of the radiators getting hot at the same time, but the difference between upstairs and downstairs is still significant, do I start looking at covers, radiator sizes, that kind of thing?

ethicalpaul · February 5

Personally, I would replace the main vent, then buy a #5 Maid O Mist vent for each radiator in a cold room, and a #4 for each radiator in a warm room.

Once you do this, you want to let it run for 3 days to see how each room feels to you. Then if you need to make changes, make very small changes then see how it goes. With Maid O Mist vents you can easily swap the orifices on top of the vent instead of having to change the whole vent.

tacoma1930 · February 8

In the process of replacing vents.
Does this seem like the capped-off former radiator line that would have been in the kitchen?

KC_Jones · February 8

1 1/4" for me would definitely indicate a radiator takeoff that use to be there.

Waher · February 12

Is your pressturetrol on a pigtail?

That 1-1/4" pipe used to feed a radiator up to 55 EDR.

That main vent should be replaced with at least one Gorton No.2 vent (make sure it rattles like a cowbell before you install it and you'll need a 3/4 to 1/2" brass bushing) or Barnes & Jones Bigmouth (already a 3/4" thread to directly swap for the existing vent).

tacoma1930 · February 15

Appreciate all the help! edit - I need to get a better photo to see where the pressuretrol is connected.
Main vent is next to purchase. And then I think fixing the hot and cold rooms will be a matter of covers and vents.

getting to know my new 1930 single pipe system

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