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Trane system check valves removed ?

mstrbillmstrbill Posts: 24Member
Question for all of you vapor system professionals out there . There is a trane vapor system i may be servicing and it has all of the original components still intact with the vent valves , float vents and DRT and check valves . My main question is ; can the check valves be removed since the boiler has been changed to a modern Weil Mclain with a standard pressuretrol and lower water level than the original boiler , and just let the returning water just gravity feed into the boiler even at 2 psi , as all other 2 pipe systems work ? The rads all have traps on them and not trane elbows . The rads also have the graduated supply valves from trane . The system has both dry and wet returns all piped correctly back to the boiler and DRT . Are the check valves necessary anymore due to the hartford loop configuration , the low water line , and possible sludge buildup in the checks . I believe the DRT is not needed anymore along with the checks , Correct me if i am wrong . I will install a vapor stat on the boiler at the very least , i know all about trying to keep the old systems at ounces of pressure . The concern i have is the possible sludge in the check valves causing poor return to the boiler . I am prepared to remove the swing plates inside of them , and the DRT steam connection and bypass if needed . What are your ideas ?


  • Dave in QCADave in QCA Posts: 1,737Member
    edited April 15
    Yes, if you're controlling pressure with a Vaporstat, usually to 16 oz. or less, gravity return will work.

    But, I want to ask the question, how many times have you encountered a steam system that was totally and completely intact, and you thought to yourself, "Gee, if someone had only ripped out half of the stuff because they thought it wasn't needed anymore, then this system would be so much better"? I suspect the answer is never.

    Yes, wet returns tend to get gunked up, the pipe much more so than brass fittings. All you need to do is leave a valve in the line so it can be easily flushed out.

    Those check valve are required in order for the return trap to function. And, if that vaporstat gives out, and the next tech doesn't know why a vaporstat is there, it might be changed out to a different control not capable of keeping low pressure. Right now you've got a system that will fully function, even if pressure goes up. How lucky. I think you should maintain it in place. It seems like the right thing to do.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • Jamie HallJamie Hall Posts: 10,455Member
    You mention also a lower water line.

    Potentially Very Bad News.

    Install the new boiler so that the water line is the same as the old one, or as near to it as you can. The water level in the whole system is dependent on that, and -- unless you are prepared to do a lot of work -- messing with it will make you very unhappy.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,793Member
    Height of the boiler waterline is very important to the system functioning correctly as mentioned above. Take the check valves apart and clean them. Maybe add some boiler drains so the lines can be flushed.
  • SteamheadSteamhead Posts: 12,981Member
    Even if you're running a Vaporstat, there's nothing wrong with a belt-and-suspenders approach. Leave the checks and DRT as they are unless there is definitely a problem.

    I'd look at adding a Vaporstat and using the Pressuretrol as a backup.

    The lower waterline may or may not be a problem. If it's low enough that it exposes connections between drips from various parts of the system, that's a problem because steam can short-circuit through a drip connection that is not under water. In that case you'd need to lower the drip connections so waster fills them again.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
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