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Vapor System

I was called upon to repair some leaking steam main piping but there is alot more going on than just leaking old piping. This system is a real mess.

I have been able to identify (thanks to Dan and this site) that the system is a Warren & Webster type R vapor system. Complete with an alternating reciever, vent trap and drip traps at the end of each of three steam mains.

There are two short steam mains which still have the original W&W drip traps on them. The drip traps are not unlike an F&T as they have a float and a bellows, the former residing in the top of the trap. The top of the trap is piped over to dry returns for air elimination through the vent trap at the boiler. The outlet of the drip traps drop to wet returns.

On the one long steam main (this is the one that's leaking, along with the dry return next to it) someone at some point installed a new drip trap (drip trap jpeg) but an unvented model without a bellows. The crossover to the dry return was eliminated and a main steam vent installed in the tee in the dry return. This left the steam main unvented except through the radiator traps. The piping also lacked some insulation, was poorly hung and it wasn't draining. I assume this is what is killing the piping as this is not the first time it's being replaced. The dry return from the radiators served by this main drain into the wet return but also connects to the other dry returns for venting purposes.

I have replaced the piping and re-hung it with proper pitch and will re-insulate. I have also installed an F&T at the end of the main and installed a main vent on the F&T.

I have yet to test the alternating reciever and the check valves.

Questions:

1) I was told by a trap Man. Rep. that the vent should go on the inlet side of the F&T, but the lost art says the outlet. Can I assume that the lost art is correct? If I don't need it on the outlet I don't have to rely on the bellows in the F&T if I put it on the inlet.

2) Should the main vent be removed that was installed in the old crossover piping tee in the dry return?

3) Why are the drip traps required? is it because of the dry return dropping into the wet return? If it were just the end of main couldn't the main just drip into the wet return along with a crossover for venting (without a drip trap)?

4) If the drip traps floats work but the bellows don't I am assuming I could just pipe it like a crossover with an external thermostatic trap. Or would it be better to install new traps altogether?

These are not the only problems this system has, the boilers are a real sight too.

Thanks in advance,

John Taylor
Custom Climate Systems, Inc.
Dexter, MI

Comments

  • John Taylor
    John Taylor Member Posts: 4
    No Opinions?

  • Steamhead
    Steamhead Member Posts: 17,387
    Just got home, John

    so I have some time to look at this while The Lovely Naoko makes dinner.

    1. An F&T trap will pass air, so technically you don't even need a vent if you pipe up from the trap outlet to the dry return. That said, the bellows in an F&T may not pass enough air to vent the main properly, especially if the main is long. So the place to add venting capacity, if needed, is on the inlet where the bellows will not restrict it.

    Dan's idea of venting the outlet of an F&T finds its use where a boiler-feed pump's higher inlet creates a water leg in a formerly open return.

    Inadequate venting can turn the condensate into a mild carbonic acid, which eats pipes.

    2. The added vent in the dry return probably isn't needed, but it will do no harm where it is.

    3. To answer this you will need to ascertain whether all those wet returns pass thru the Return Trap piping. Since the steam mains are trapped into the wet returns, they probably do. You don't want any steam pressure in the returns that pass thru the Return Trap piping.

    4. I'd rebuild those Webster traps rather than replace them. Try the Tunstall (www.tunstall-inc.com) or Barnes & Jones (www.barnesandjones.com) online catalogs to locate replacement parts. This is much easier than replacing those traps or installing crossover traps (although that would work).

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  • John Taylor
    John Taylor Member Posts: 4


    Thanks for the response Steamhead. I think the patients going to make it.

    After finishing the piping repair on Friday last week and replacing the one unvented drip trap water level in the glass was all over the place. We worked late but couldn't get to the other drip traps. Dry returns were hot at start-up and I was afraid we had a bunch of bad radiator traps (house has 22).

    When we returned Monday the system had overfilled and had been hammering. Took the check valves apart at the return trap and made sure they were working, checked the wet returns for flow, cleaned out the drip traps and found that the floats would still work. The bellows were shot, so we did away with them and vented them to atmosphere. I thought about rebuilding them but I had already exceeded my estimate for repairs and I'm still hoping they will bite the bullet and let me re-pipe the boilers too.

    When we fired it back up the returns stayed cool and so did the return trap crossover. Water line was rock steady, radiators throughout the house were heating evenly. You could smell that kind of "old heat smell" that you get from something that hasn't heated in a long time. I'm pretty sure I even experienced the alternating receiver operating.

    What an empowering feeling!! I just love working on old things and having them work like they were intended. Especially those things others would consider a lost cause or not worth the effort.

    Thanks again,

    John Taylor

    Custom Climate Systems, Inc.

    Dexter, Michigan
This discussion has been closed.