One-pipe steam trap ??????

sraburne · October 2009

Working on a Steam boiler. First of the season in Kansas city. This is a one-pipe system, But at each radiator at the location were the air bleed should be there is a small 1/8 " steam trap. that is piped back to the boiler. The house is 1920's The boiler was replaced in 1998. The Original call was the boiler is over filling. I pulled and cleaned the low-water sensor and flushed the heat exchanger. Than cycled the boiler by the electrical service switch. to see if it would overflow during shut down. The reason I tested it like this, I could not get the pressure switch @ 1psi to satisfy. I think it may be the traps not closings. Than at shutdown the boiler is flooding due to the traps are finally opening after some time and releasing the condensates in the radiator

Jamie Hall · October 2009

sounds like...

a KMC, or some similar system which used air lines like that (and often controlled the radiators through restrictions on the air lines). These things do go back to the boiler -- but they have to have an air/vacuum release where they get to the boiler. Look and see what you can find. It is possible that when the boiler was installed (yeah, I know, 10 years ago, but...) something was changed that hadn't ought to have been...

That is... if it is a KMC or something of the sort, there really shouldn't be a trap, even a tiny one, at the radiator, unless it opens reliably on air or vacuum (in which case, it's more like a vent...).

One way or another, there has to be a way for air to get out of the system when it fires, and to get back in when it quits.

nicholas bonham-carter · October 2009

KC vapor system

is it like this?--nbc

[url=http://www.heatinghelp.com/files/articles/1390/126.pdf]http://www.heatinghelp.com/files/articles/1390/126.pdf

Steamhead · October 2009

That's an "air-line" system

also known as the Paul system, after Andrew Paul, who brought it to market.

In the old days there was probably a vacuum exhauster that sucked all the air from the system thru those air lines. That made the system very quick to heat, and allowed it to make steam at lower temperatures.

Where do those air lines end? If they're tied into the boiler somehow, that may be the problem.

sraburne · October 2009

thanks

Thanks for the information. I saw the drawing of the KMC on the posting below yours. Their may have been some parts of the system removed during the new boiler install. I should have taken a picture of the unit.

sraburne · October 2009

Thanks

Yea It look like the same system, but with some parts missing. The piping from the trap goes directly in to the wet return. Their is one other different, at the radiator in the drawing the air bleed looks like adjustable valve, the one I have looks like a steam trap. thanks again I should have taken pictures.

sraburne · October 2009

thanks

All the pipes connect together, than connect into the wet return below the boiler. If the piping is called the wet return on a one-pipe system. you guys have been great thanks

Steamhead · October 2009

There's your problem

If those air pipes connect to a wet return, the connection point is filled with water and the air can't vent!

One-pipe steam trap ??????

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