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Lux thermostat not calling for heat

moemah123 Member Posts: 55
edited December 2022 in THE MAIN WALL
Hi Everyone,

I am new here and would like some pointers.

My lux thermostat suddenly stopped calling for heat. There is no indication on what is going wrong and house is losing heat fast. I am posting pictures of the system.

Some details:
Couple days ago I could hear air bubbles in system.
Today I didn't hear it but I realized I heard my boiler only kick once or twice.
Increasing temperature in thermostat didn't help start boiler, its been 1 hour and system is on standby
When I see system call for heat, the red box (pump?) in the picture has water going through it sound. (But i don't hear water flowing in tubes upstairs) If I lower temperature to below room, the water stops. So I can imagine thermostat doing something except calling for heat.

Guidance and pointers would be appreciated. Thanks in advance


    HVACNUT Member Posts: 5,876
    Well first, you don't have a boiler, you have a gas fired water heater trying to act like a boiler. 

    If the gauge is correct, then the system is at 35 psi, and most likely too high. What relief valve is in the water heater, and what is the extrol tank pressurized to?

    If the return is on top, and there's air in the system, then close the valve to the left of the circulator, and purge from the drain to the left of that.

    If the loop splits, you'll need to valve off and purge one split at a time.

  • pecmsg
    pecmsg Member Posts: 4,916
    35# pump pressure?