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Beckett Burner Thermostat Wiring

RossB Member Posts: 3
I have a Weil-McLain Ultra Oil U-04 Boiler. Today, I replaced my problematic Beckett NX burner with a Beckett AFG burner. The primary controller on the old burner was a Beckett R7184P with a 3 wire switching circuit from the EnviraCOM Aquastat circuit (1, 2, 3/T). The new AFG Burner has a Beckett GeniSys 7505 primary controller which only uses a 2 wire switching circuit (Tw, Tr). The new unit is looking for a simple open/close input to turn the burner on and off. The 3 wire circuit doesn't seem to offer the open/close that I'm expecting to see. I've tried every combination of the 3 wires while tripping thermostats on and off. Any experience with this is greatly appreciated.


  • Jamie Hall
    Jamie Hall Member Posts: 21,111
    Seems to me, looking over the literature, that the EnviraCOM unit only works with compatible enabled units -- like the Honeywell (not Beckett) 7184 and 7284. I have my doubts about its working with the Genisys…

    Presumably you have all the equipment and test instruments to properly set up and adjust your nice new burner?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • RossB
    RossB Member Posts: 3
    Yeah. The plumber is here with the equipment to set the air/fuel now.
    HVACNUT Member Posts: 5,026
    edited November 2019
    You cant use the EnviraCOM with the 7505. Reuse the R7184P. Is the 7505 a "P" also? If not, you can't use it anyway.
    Problematic NX huh? I never had an issue with an NX and the Ultra Oil.
    Does Weil McLain even spec using the AFG in the Ultra Oil as OEM?
  • RossB
    RossB Member Posts: 3
    Yes. The AFG is an OEM option for the Ultra. Apparently there were 3 options; NX, AFG, and a Riello. I bought the entire AFG burner assembly directly from Weil-McLain - factory set for my U-04 boiler. I checked all the spacing anyways and it was spot on. We just checked the CO2 and it's running at 9.5%. The NX was a nightmare. I've had trouble since it was new, replaced just about every single component of the burner, and had half a dozen pros tell me it was their least favorite burner. It's been sporadic flame failures and lock-outs for years.

    We just heard back from the "expert" boiler guy. Turns out the answer is to jumper Tr and Tw together at the primary controller and run it. It had a jumper on it when I opened the box. I mistakenly thought it was left over from testing or something and removed it. Seems to me that if you leave it jumpered, you rely on the aquastat to control the burner based on boiler temp and not demand. The boiler will stay hot all the time, regardless of the demand, and the circulators will do their thing. I'm still going to poke at it a bit. Doesn't seem terribly efficient.
    HVACNUT Member Posts: 5,026
    What model Honeywell aquastat? L7224? You should be able to turn off the Lo setting and it will be "on demand". I didn't think of mentioning the jumper on the primary. Sorry. Thought that was a given.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    9.5 CO2 is not great combustion numbers. You need to get a good combustion person in there to check nozzle, z-dimension, pump pressure, draft, smoke, etc.