0

I have a 7 zone circulator pump heated using Navien combi-boiler. 3 thermostats are connected to the boiler, and the remaining 4 are connected to a Taco SR-504 relay. All the connections have 2 wires, R and W.

Even though each thermostat is able to control the corresponding pump, only the thermostats connected to the boiler is able to call for hot water to supply heating. So if any of the 4 were to call for heating, one of the other 3 would need to be on as well for it to actually heat up. Would pigtailing the other 4 thermostat wires to the boiler work to fix this?

enter image description here

enter image description here

9
  • 1
    Hi there, the boiler model is Navien NCB-250/150H. I've added pictures of the wiring. 4 thermostat wires connected to the boiler, 3 to thermostat terminal and 1 to recirculation; and 5 thermostat wires connected to relay
    – Steve
    Commented Nov 26, 2023 at 17:49
  • 2
    You have the "Isolated End Switch" terminals connected on the relay box, which should be connected to your boiler already, according to the manual linked above. Can you trace those wires and see where they go?
    – Moshe Katz
    Commented Nov 26, 2023 at 18:03
  • 1
    Based on the labels that the installer tagged, the isolated end switch wire should be connected to the recirculation terminal of the boiler.
    – Steve
    Commented Nov 26, 2023 at 18:46
  • 1
    Dumb question - have you checked the fuses? If things are wired right, and used to work, and the wires haven't been chewed (or sometimes if they have, and caused it) a fuse might have blown. If it never worked right, more likely a misplaced wire or choice of wrong terminals (or even a DIP switch setting.)
    – Ecnerwal
    Commented Nov 26, 2023 at 19:14
  • 1
    Have you checked if the "external recirculation" setting is turned on? Without it, those terminals will be ignored.
    – Moshe Katz
    Commented Nov 26, 2023 at 23:54

0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.