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GV90+ output temp low

z987k Member Posts: 2
I have a Weil-Mclain GV90+. The temperature on the circuit board inside the unit seems to be reading quite high. It was set to 180, and it will drop to 160 before it fires up and gets it back to 180 again.
The analog temp/pressure sensor at the outlet of the boiler reads 120 as does the one immediately after the pump(I don't know why there's 2 so close together) when the digital one on the circuit board reads 180.
I turned it up to 200 and now the 2 analog thermometers read ~135.
The reason I was even looking at this is the heat was not keeping up with demand. With an outside temp of 15F and the thermostat set to 68, it was only getting to about 60, no higher. Normally when you raise the temp on the thermostat on the wall it is very quick to raise the room temp.

I figured the temperature sensor for the boiler was faulty, so I replaced that, but that did not fix the issue.


  • Peter_26
    Peter_26 Member Posts: 129
    Pictures of system?
  • z987k
    z987k Member Posts: 2
    I figured it out. In case someone has something similar -

    The rear pump, of the two in the boiler, which circulates hot water out of the boiler, was pulling too many amps(motor going bad) and the circuit board was cutting power from it(presumably there's a resetting over amp controller on the board). New pump and all is good.