Inside Sales & Design

Greg Maxwell

I was on a steam system for a customer the other day. It is a system that probably was installed in the 40's. The rads are colums style, nothing special. I started to measure them, and we came onto some that were 2 pipe. I had never seen 2 pipe mixed with 1 pipe. After measuring, I went down to the basement. It was an old American Standard coal conversion, and sure enough, there was a main vent where the 1 pipe was returning, then there were small returns that were coming back to the boiler, looked like 1 from each rad. No F/T traps in any of the returns. I was baffled! I thought, how is this even working. I also got the info from the customer that they have very uneven heat in the house. Has anyone ever seen this? I warned the customer already that just changing the boiler may not resolve issues with the uneven heat. I welcome any suggestions.

nicholas bonham-carter

low pressure system

these vapor systems worked without traps, because small orifices, or metering valves would be sized/adjusted to let only the amount of steam in which can be completely condensed. they were the cadillac of systems as long as they didn't change the adjustment to let too much steam into each radiator.

they need a vaporstat to keep the pressure at a few ounces, along with a good low-pressure gauge [gaugestore.com] to verify. they also need substantial [gorton #2] main vents on the end of the supply, and the end of the dry returns. on my 55 rad system, i have 17 main vents, venting at 1-2 ounces, and all gravity return.

see if you can take a few pictures of the valves on the radiators, and post them here so someone may have some further suggestions. you may also search here for "vapor system", and "orifice".

some thought needs to be given to the height of the old vs. new waterline to keep any wet returns wet.

your customer won't believe the difference in comfort, and lower fuel consumption, when you are done!--nbc

Dave in QCA

Vented 2-Pipe

I agree with everything that Nicholas has said.   In addition, there is another possibility too.  There are some systems that are vented 2 pipe.  The radiators have a vent, a supply, and a return.  The return is connected to a wet return.

Greg Maxwell

confusing steam system

I do not believe that this is a vap/vac system, because there are standard air vents on the rads that are 1 pipe, and a standard main vent on their return. The vented 2 pipe makes more sense in this case, because they all connect to a wet return. I have just never seen both 1 pipe and 2 pipe on the same system, and when the customer was complaining about no heat out of the rads, I started to suspect that may have something to do with it.

Dave in QCA

Vented 2-pipe variations

In most vented 2-pipe systems, the return piping is carrying condensate only, and it allows for smaller risers coming to the radiator because they are carrying steam only.  They usually work quite well.  I suspect that if some of the radiators are not heating, there is a problem with the venting.  Either some vents have failed closed or are clogged, or the other possibility is that some vents have been replaced with vents that are too large, and those radiators hog the steam.  Of course, a malfunction main vent will mess up the balance too.



I have also seen a combination system where all of the first floor radiators were one pipe with vents.  All of the second and third floor radiators were 2-pipe.  No traps and no vents.  The condensate and air travelled down the individual return linesto the basement.  At the ceiling level of the basement, there was a radiator vent on every return line.  The return line connected to to a wet return, below the boiler water level.  The system works great!  It allowed for the steam risers running up to the upper floors to be smaller than they would be otherwise.  Of all of the variations that Dan shows in his books, he does not show this one.

Maine Vent

Combo 2 Pipe/1 Pipe

Greg I have 4, 2 pipe rads and 5, 1 pipe rads, no traps all with vent-rite vents. They all deliver even heat, system works very well. Mine are my 2 pipe rads are Crane I believe.

Greg Maxwell

problem steam

I have advised the customer about the piping situation, and changing all the vents. He knows that the piping could be an issue, and he is going to address it with the homeowner. If he gets the job, I am going to follow up with him during the process to hopefully learn more about this. Thanks, Greg