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Weil McLain Ultra 155 will not light off because it is not getting fuel

Tom Elam
Tom Elam Member Posts: 57
The boiler will not light off. I have air flow and spark but no fuel.
I can see the blue arc if the igniter through the view port and hear the relay click.
I do not smell natural gas from the boiler exhaust
There is good air flow from the exhaust
The gas supply pressure to the boiler is 10.5"H2O
I can hear the relay for the gas valve click and have 24VDC to the gas valve
Resistance across the gas valve solenoid is 185K OHMS
Both fuses are good on the control board.

I would think the resistance across the fuel valve solenoid should be 0 OHMS, can anyone verify that for me?

Thank you for your help,
Tom

Comments

  • the_donut
    the_donut Member Posts: 374
    Check for amp draw on gas valve.
  • HVACNUT
    HVACNUT Member Posts: 4,215
    Does inlet pressure drop during ignition?
    Any codes? Series 2 or 3?
    I've replaced many gas valves on the Ultra.
    Use the CP# to see if its warranty.
  • Tom Elam
    Tom Elam Member Posts: 57
    Gas pressure does not drop when the fuel relay kicks.

    I do not have a meter to measure amp draw on the solenoid
  • Tom Elam
    Tom Elam Member Posts: 57
    The boiler is 14 years old so I think it is a series 1
  • Tom Elam
    Tom Elam Member Posts: 57
    fail to fire code

    The fan is a little noisy and I don't have the ability to see the fan speed. I would think that the solenoid for the gas valve to open wouldn't kick if the speed permissive wasn't met.
  • HVACNUT
    HVACNUT Member Posts: 4,215
    Bad or dirty gas valve
  • GBart
    GBart Member Posts: 746
    call a pro, gas is not to be trifled with
  • JUGHNE
    JUGHNE Member Posts: 9,007
    Zero Ohms equates to no restriction to the flow of current creating a dead short circuit........overload blowing fuses or boards.
    Your gas valve coil reading sounds as if it could be correct.

    Sounds like you have a mechanical issue with the valve.

    Remember..... if stuck shut......then somehow opens when called to do so.......can also become stuck open...........much worse problem than you have now!
    delta TSuperTechZman
  • delta T
    delta T Member Posts: 864
    Natural gas or LP? 10.5" static is quite high for NG, but a little on the low side for LP. Don't think its related to your problem, but might be something to get corrected when you have the gas valve changed, which I'm pretty sure is your problem.
  • newagedawn
    newagedawn Member Posts: 586
    bad gas valve
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
    Tom Elam
  • GBart
    GBart Member Posts: 746
    Natural gas supply pressure requirements
    1. Pressure required at gas valve inlet pressure port:
    • Maximum: 13" w.c. with no flow (lockup) or with
    boiler on
    • Minimum: 5" w.c. with gas flowing (verify during boiler
    startup, while boiler is at high fire)

    Propane supply pressure requirements
    1. Adjust propane supply regulator provided by gas
    supplier for 13" w.c. maximum pressure.
    2. Pressure required at gas valve inlet pressure port:
    • Maximum: 13" w.c. with no flow (lockup) or with
    boiler on
    • Minimum: 4" w.c. with gas flowing (verify during boiler
    startup, while boiler is at high fire)

    from the manual
  • Tom Elam
    Tom Elam Member Posts: 57
    The Weil Mclain tech verified that the gas valve solenoid was bad. Replaced the gas valve and now we have fire again!
    HVACNUT