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losing pressure

Mad Dog
Mad Dog Member Posts: 2,595
in THE MAIN WALL
Its somewhere you just have to find it, I would go over that towel warmerand toe kick, I;ve found tiny leaks on them...that baffled us for a while. Could also be an air vent. The snowmelt system I put in was losing pressure too with no noticable signs of water and I knew the loops were tight. This system, like yours probably is was not under constant pressure from a feeder valve. I finally isolated it to the air vent on top of the sparco air eliminator, I teflon-taped it up adn made it real tight, System has been tight as a BIRD dog's heiny since then. Mad Dog

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Comments

  • Al_11
    Al_11 Member Posts: 34
    losing pressure

    I have a munchkin 92% boiler installed on a 50/50 glycol solution system in a 4 season cabin. It has a primary loop with a pressure differential valve and 3 zones. 2 bedroom zones and a main with a baseboard circuit in parallel with a circuit containing a towel warmer, 4 cell radiator, and a toe kick under the sink, both circuits are balanced on the return. The Zones are H/W Zone valves.
    The problem is that it will run for weeks with out a hitch and then it will shut down on low pressure cut-out.
    3 times I have found the system at 50deg. and 0psi.
    Each time I add solution with my pump to 12psi ( max my electric pump will do). Start the system up and the pump will raise it to 18psi. Heat circulates everywhere, the system has been bled, the system has been installed according to pumping away principles. The basement is exposed and everywhere foot of the piping is exposed, no leaks are found.
    The last time it happened with in a matter of hours.
    I went to bed it was 18psi and by 3 am it was shut down and 0 psi. It only takes a squirt to raise the pressure back up to 12psi.
    I am a contractor, I have put in lots of systems, I don't understand this at all. Thank God it's my cabin and not a customers.
    Help!
  • Canuck
    Canuck Member Posts: 57
    How much expansion?

    Your line of 'just a squirt...' might be the indicator here. I do a lot of radiant for carwashes and have had some nuisance sites where the same pressure problems have occurred. Almost always it's a combination of a small pocket of air and too little expansion/glycol reserve.
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    NO reserve...

    If the expansion tank is charged to 12 psi or greater, you're not pumping any reserve fluid into the system to conmpensate for the elimination of gasses in suspension in the fluids.

    You can do one of two things, A., get a pump that has the ability to generate more than 12 PSI or whatever your expansion tanks diaphragm is set for. Pump it up to say 15 PSI with a 12 PSI charge on the diaphragm. THis will give you a little reserve to compensate for volume change, or B., lower the diaphragm pressure to 8 PSI with 0 PSI on the water side. Now when you pump it up to 12 PSI, you have some reserve fluid on the diaphragm to compensate for volume loss from deaeration.

    B can be tricky if you have a tall system.

    ME
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669


    If it is a new system then it will still have a small amount of air in it that is being bled out. Because you have NO reservoir with the bladder tank set at 12 PSI and the system at 12 PSI just a cup of fluid lost or the same amount of air will drop the pressure to 0.
    As I have always said if you are using glycol don't use a bladder tank.
    I use a 15 gallon ASME tank with a sight glass to see how much reserve is left.
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