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One Pipe Steam Radiator System


Sorry for the long message here, but I wanted to give all the details I could think of that would matter in this situation. Here's the story.

We bought a 1920's maybe 1930's house in Northeastern Pennsylvania near Scranton. It has a street level floor, a second story and a full attic. Below the main floor is a full basement with a laundry room that is mostly unfinished bare basement, then there is a finished area for a toilet, shower, hallway to the sink, and then a short hallway to a living space with small kitchen, and off of that a finished storage room that was previously used as a bedroom by the previous owner.

We moved from California, and the only experience we had with Radiators there was that they were decorative non working heat devices found in a few old buildings.

I've searched the internet for information about this type of radiator system and almost all information is about a two pipe systems, so I have not learned much yet.

On day 3 of living in the house we found that there was a major leak in one of the steam pipes that is in the sub basement. Normally I would want to try and fix this myself, but with the lack of information at that time we called a local heating / plumbing outfit that came out and gave a quote of $1000.00 to replace the pipe. This was about 20 feet of pipe, and he installed a faucet on the line to drain it apparently.

The $1000.00 seemed quite steep, but we got the seller to pay for most of it, so we just had them do it.

Later on, after more research, I found information about how the steam system works, and it seems to me that none of the pipes should run below the level of the boiler. This pipe comes out of the boiler and turns down and goes through a hole punched in the small area of concrete that the boiler sits on, and then turns and runs under the basement floor in the sub basement and then back up into a room on the other side of the basement that has a radiator mounted on the wall about 7 feet off the floor. Directly on the other side of that wall there is another room with another radiator hanging on the wall in the same fashion.

The reason I came to the conclusion that the pipe should not run below the boiler line is that what I read is that the system sends steam through the lines and delivers it to the empty radiators, and at some point the air valve in the side is caused to close and that stops the cycle until that valve cools sufficiently to open again. So with that it mind, wouldn't the pipe that runs below the boiler fill with water and have to become super hot to then boil the water and give off steam again to activate those two radiators? Those two radiators are above the boiler level by 7 feet, and I guess the line was run under the floor so the pipes would not run through the basement rooms above the boiler height.

This pipe running below the boiler seems to me to be very inefficient and since it is un-insulated, a huge waste of heat.

My questions are:

Should plumber have replaced this line, or should he have recognized the weird installation and suggested something else?

Also, should all of the steam pipes that run from floor to floor be insulated? I read somewhere that they should, but then someone I spoke with thought that the heat they loose would just heat the room and was not a big deal. It seems to me that the radiator should be doing the heating, not the pipes.

If anyone wants to see pictures of the bizarre setup in the basement, I'll send them.

Thank you for any and all help.


Re: One Pipe Steam Radiator System

You're right...this is a bizarre setup.

A one-pipe steam system relies on gravity to function. The pipes should all pitch from the boiler to the radiators. The heated steam rises to fill the radiators. When it cools and condenses, it should returm (by gravity) to the boiler.

I seriously doubt that there is much (if any) heat being given off from the 2 radiators that you mentioned.

Re: One Pipe Steam Radiator System

I can't see how the system you described would work at all. The entire pipe below the boiler would fill with water and act as a plug to prevent the steam from flowing. Can you post a picture of the boiler and one of the radiators on here?

Re: One Pipe Steam Radiator System

Thanks for confirming that this setup is wacky.

Here's some pictures to show what I'm up against.

What do you think about how the HVAC guy handled it by just installing a new pipe and acting like nothing is wrong.

The pictures show the boiler and the pipe going into the sub basement and the other two show the wall mounted radiators. Notice the extra air vent shooting off one of the pipes of the white painted pipes.

Thanks for the help.


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