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I installed an Ultra 105 with DHW and 2 heating zones. I used a Taco 502 relay connecting my 2 heat zones. The DHW is tied into the U control on the Ultra and the 2 circs for my heat on the 502. I connected one heat zone to zone 2 on the 502 and the other heat zone to zone 3 on the 502. Only zone 2 is juiced I cannot get juice through zone 3 for the life of me.
I tried jumping the t stat I checked the circ (which is good) I cheched all wiring for a reason I don't know about I cannot get power to the other heat zone using the 502. I wonder if I need to use a 503 relay? When the Ultra fired up everything is fine DHW and the other heating zone.
Anyone who has installed a system with 2 heat zones and DHW let me know what you did for controlling the circs. > Thanks