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PLEASE HELP: Taco circulating pump not getting power?

Current setup I have is 2 zone oil boiler heating system, zone 1 is radiant floor heating and the 2nd is baseboard in an addition. 

The 2nd zone valve has a end of line module on it, although the valve is need of replacement since is mechanically failed inside stuck in the closed position.   V80431036F are the valves and are expensive. I'm curios if I can I replace with less expensive sweat valves?  I upgraded the boiler myself and it was been working fine for 4 years; and before anyone says anything  I did have a good teacher until he passed away-my grandfather was a  master plumber and taught be a lot... although I should have payed more attention to the electrical aspects.

Zone #1 has been working with no issues off the Honeywell simple heat only round thermostat.  Zone #2 also has a round simple heat only thermostat.   When wither of the thermostats call for heat, a Honeywell R1282B relay engages and send 28 volts through the line all the way to the aquastat's terminal for the thermostat. 

The issue I have is that the circulating pump is not engaging, I thought it was the triple aquastat, so I swapped the Honeywell triple aquastat with an extra one I had laying from a old boiler that was replaced but had a newer aquastat on it.  After replacing the aquastat, I  thought as soon as the boiler got to temperature and there would be a call for heat that the circulating pump would get power...well I was wrong. 

I know the circulating pump is working, since the relay in the aquastat is switching the "L2" contact to the "C2" contact, and when I use a jumper across them above the aquastat, the circulating pump works!

Will the aquastat only send power to the circulating pump when the boiler has reached the desired temperature range?

Could a bad capacitor on the circulating pump cause some type of incompatibility with any the relays-I know this could be a long shot?

When I have a call for heat, I do get 28 volts at the thermostat contacts on the aquastat, so is most likely that I have two bad aquastat relays?

Please offer any assistance!


  • billtwocase
    billtwocase Member Posts: 2,385

    You are jumping the ground if you are jumping L2 and C2. You need the check C1 for power. #1 is and should always be wired hot, and #2's ground
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