Buderus 2017 on a gas boiler, term 12 needed?

GW

Does anyone have an idea why the wiring directions show both line voltage and a switched leg going through the 2107? I have a guy calling us where the 12 term died. I fed the Honeywell with live power. The 10-11 are still switching the HW on and off heat call. I couldn't seem to get an answer for the Bud. Thanks, Gary

Ironman

Terminal 12 is the manual reset high limit. The high voltage terminal (L1) of the aquastat must be fed from that.

Oil burners – factory jumper between terminals 12 & 10, brings 120V from 12 to 10. When contacts close between terminals 10 & 11, 120V power is sent from terminal 11 to Hot on the burner (terminal 4 is the neutral).

Gas burners – remove factory installed jumper between terminals 10 & 12. The contacts between terminals 10 & 11 are now “dry” (no voltage present) and switching to the burner is now low voltage between terminals 10 & 11 on the R2107 and TT (or RW) on the boiler aquastat.





Bob Boan


Bob Boan

GW

Thanks Bob, the HW is the main boiler control, the 2107 is acting as a fuel savings device. I can see the point when the boiler control is removed (on an oil boiler). I'm simply trying to justify 'insisting' the home owner 'must' have a new 2107 installed.

Ironman

Gary,
The manual reset is under the black cap to the left of the temp dial.
There's also a fuse under the small cap to the right of the display.