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Boiler Tripping, need suggestions (incl. link to video)

Jeff Elston
Jeff Elston Member Posts: 289
Why is the pressure 50 psi.?

A flow switch is not a valve it is a electrical switch that is on the pipes. It has a paddle in the flow of water, when the water moves it pushes the paddle and closes the switch. Typically this switch ensures water is moving in and out of the boiler therefore allowing the burner to lite.

Can you take pics of your piping layout?

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  • Craig C
    Craig C Member Posts: 2
    Boiler high-limit tripping (incl. link to video)

    We have a Teledyne Laars boiler that supplies return hot water, shared to three transfer tanks (one for radiant heat floors, two for domestic hot water). Demand is a function of one or more of the transfer tanks dropping below a certain temp.

    For months I have had problems with the boiler high-limit aquastat tripping (set to 210) - randomly it seems. The normal operating temp is set to 180, pressure around 50 psi. At I thought it was a bad aquastat, but after replacing both aquastats (high-limit and operating), I still had the problem.

    Finally, I set up a video camera, and managed to capture the event. See this link to witness the event occurring:

    Any ideas what might cause this? Is it possible for the pressure & temp rise like this if the water isn't circulating but the boiler operational? What other possibilities might folks suggest.
  • Jeff Elston
    Jeff Elston Member Posts: 289

    The pump for the boiler must run when the burner is on. There should be a flow switch to ensure flow.

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  • Craig C
    Craig C Member Posts: 2
    Flow Valve

    I've posted a different, longer version of the event here:

    What I can see/hear at 16 seconds is the boiler comes on and seems to be running OK, but then suddenly the pressure spikes around 3 minutes.

    If it was the flow valve, any idea why a flow valve would close? Shouldn't it be linked to the boiler controls so it could not close as long as the boiler was running?
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