DIY Home Improvement Forum banner

Wirsbo radiant heat not triggering pump

2327 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.


See less See more
1 - 3 of 8 Posts
Where the wires fro m the Ra89A connect to teh control board. Put a jumper across them. If the RA89A runs the circ after that. The problem is probably in the control board.
  • Like
Reactions: 1
Ohm the ends switches when they should be closed. If they have zero resistance, its not the end switches.
One or more of the end switches may have failed some time ago. And those zones were only getting heat when the other zones were calling.

Don't know which way will be cheaper.
1 - 3 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.