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Wirsbo radiant heat not triggering pump

2319 Views 7 Replies 3 Participants Last post by  kernbrian
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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Thanks, I have tried that jumper and it does trigger the relay and start the pump. I asked the supply house and while their advice is taken with a grain of salt they thought it unlikely that the board was smoked if all of the LEDs worked as they are supposed to which they do. For the $90 it costs it may be worth trying over a service call but I am concerned it wont fix it. Could the older valve actuators play into this since they have end switch outputs?
While it seems bizarre for all of the end switches to fail that may be what has happened. I do not get continuity across the red end switch wires when there is a call for heat and the valve is open. If I short across any of the end switch posts from the valve actuators the pump runs and the same is true if I short across the actual end switch output at the end of the board. one of the actual valves is leaking a little so I may just order a new valve insert and 5 new actuators to see if that remedies it. The board cant send the pump signal if it isn't getting it from the actuator. Does that sound reasonable? Also, in general is it cheaper to order these things online than to get them from the local supply houses? Thanks again for all the help!
beenthere, thank you very much, that makes good sense. The actuators are roughly $57 for the new style online and I have not priced them at the wholesaler. I think logic tells me that is my problem and if I make a $285 mistake at least I have spares, they all fail sometime. Thanks again to all!
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