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Need help wiring Buderus GB142-45 circulator pump relay switch and AM10 module

fishing66 Member Posts: 3
Cliff Notes Version: Can anyone please walk me through proper terminal connections to wire a circulator pump relay switch and AM10 module for a Buderus GB142-45 (propane conversion)

Encyclopedia Britannica Version: Unit installed 09/2019 and worked perfectly for 10 years. I clean it myself annually, have replaced the ignitor and ionization electrode etc.

Last week, I had a Buderus tech come out to do a 10-year inspection on it. He said, "You don't have a relay switch on the circulator pump and you need one". OK, install one. He installs it....the unit would fire for the first heat cycle and then would not respond to heat calls from any of the three zones. In the attached photo of the relay switch, the zone valves are controlled by the brown wire and were hooked to the TT terminals. The white wire went to the red plug of the AM 10. As before, no dice, boiler would not respond to heat calls. I jumped the WA terminal and the boiler fired right up. Plumber tells me to move the white wires from XX to TT and the boiler now functions properly except that the AM10 does not work. He said that power wiring to the relay switch is illustrated incorrectly in the Buderus manual and they told him, " "The installation manual contains an error which they never acknowledged. The manual says power wires for the relay are pulled off the pump circuit but it should say to take power off L1 and L2 off of the boiler circuit and then use X X on the relay to tell the boiler to fire. L1 and L2 from the relay should be put on L1 and L2 on the boiler." I don't know what that means. I am out $1500.00 and now have a boiler that fires constantly. Can anyone please lend a hand with this? Thanks.



  • Ironman
    Ironman Member Posts: 7,066
    edited December 2019
    Why would you need a pump relay after it worked fine without one for 10 years?
    Both space heating circulators can be connected to the "PK" terminals as long as they don't draw more than 5 amps combined.
    I would call him back and tell him that he has to put back exactly like it was and refund your money or else.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • fishing66
    fishing66 Member Posts: 3
    Bob, thanks for your note and I completely agree, he forked me over. I'll deal with him separately but for the time being, want to get the boiler back running correctly with the AM10 module. Here is a schematic from Honeywell on wiring of the RA832A pump relay switch. Right now, circulator pump supply power is indeed hooked in common with the manifold pump to the PK terminal inside the boiler. On the relay switch, the two neutrals are wired in common to terminal 1, incoming power is wired to terminal 2 and power to the pump is wired to terminal 3. Here's a Honeywell wiring diagram...do you think the GB142 would work correctly with the AM10 if I moved the hot wire from terminal 3 to terminal 4 and then moved the white wires back to XX on the relay?

  • fishing66
    fishing66 Member Posts: 3
    Mystery Solved: I took the circulator pump leads off of PK and put them on the Ground/Neutral/Load plug. The circulator pump now always has live power going to it. I reconnected thermostat wires to the XX terminals on the relay switch and routed them to the red plug on the AM10. It's been wired this way for six hours...the boiler starts, fires, circulates and is modulating based on the outdoor temp.