I have a wirsbo radiant floor heat system with 3 zones, one controller, and a Honeywell RA89A switching relay that is used to trigger a grundfos circulating pump. The problem is the thermostats call for heat (yellow led) and then nothing more, at the output side of the control board (wires going to the RA89A) i have both 24v and continuity and I also have continuity at the board on the RA89A, it just does not close the relay to activate the pump. If I put a jumper across those terminals at the control board all fires up and works as it should, the red lights come on and the pump runs. I have already replaced the RA89A thinking it was getting weak or something but that didnt fix it. I dont get it, my fluke tells me that the circuit is closing and the RA89A should therefore be closing and activating the pump but it is like it isnt a good enough connection. I have removed, checked, and re-tightened all wire connections. Any suggestions? I hate to replace the control board when that seems unlikely to solve the problem. It for the record is a A303003 by wirsbo. Anybody have any suggestions? I have attached a picture of the general set up, in the picture I had a jumper installed, without it you would not be seeing the red LEDs on those two zones calling for heat. For the record this has all worked every heating season for 6 years and appeared to fail at this year's start up.
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