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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Phil, I replaced my 58 yr old fuel oil boiler with a used

Customer Question

I replaced my 58 yr old fuel oil boiler with a used Weil McLain gv5 boiler I purchased earlier this year... The gv boiler is a 1995/1996 unit and am told will last with proper maintenance another 50 yrs... The unit was removed during a renovation project not because it was in disrepair, but because it needed to be relocated and upgraded due to the new requirements the building needed... I have all technical manuals that came with the unit and have been trying to trouble shoot an error code myself with no success. I am getting a power and flame light flashing on the control board, and after going through all the motions am still not able to get the unit to fire... Any thoughts
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, this is going to take some work. If you can send me a clear, well focused picture of the boiler wiring diagram I will mark it up with trouble shooting instruction.... it it looks like the project is going go on for more than 30 minutes of my time, I will submit an additional service request.

Let me know if that will be OK with you. We can go from there.

To attach a photo use the paper clip icon at the right end of the tool bar above.


Customer: replied 1 year ago.
Going to get the tech manual, back in a jiff
Customer: replied 1 year ago.
Here are the schematics
Expert:  Phil replied 1 year ago.

Hello again,

Make sure the thermostat is set for heat and up to 90F for this test, make sure the power switches are on to the boiler, look for a vent damper on the flue, make sure that opens, if not tell me about it


We can go from there.

Customer: replied 1 year ago.
It's getting late, will try in the morning
Expert:  Phil replied 1 year ago.

That will work, see you in the morning.

Expert:  Phil replied 1 year ago.


Be sure not to run any of those jumper tests for more than 5 seconds, beyond the time that the boiler fires... the purpose of the test is to determine what switch is open that is preventing the boiler firing sequence and not more than a few seconds those are all safety switches... if there is air in the system or the boiler is dry the heat exchanger will be damaged or other bad consequences if you run the boiler for longer than 30 seconds, 5 seconds is safe enough as long as you shut the boiler down immediately after it fires.... once we know what is keeping the boiler from firing we can take measures to resolve the cause.