Utica Boiler....

[mrcaptainbob]

Utica boiler model MCB (MGB?) 125HD. It has a Taco pump model 007-F5 that is not running. No power to the pump. However, there is a rather large controller box on the side of the boiler. No markings on it. Inside the shield there are what appears to be three transformers. Nothing looks or smells burned. There are four terminals at the lower right of that controller, marked L1, L2 on the bottom and just above them are two more marked C1, C2. There is 120V at L1, L2. Nothing at any other terminal. Just above the C terminals is what appears to be a relay. Depressing that metal block on the top of that relay causes the Taco pump to operate. There are four zone valves that work in conjunction with the Taco pump. Either of the valves open and that pump kicks on. I am not sure if the valves are operating electrically. The Utica boiler is not fired on it's own, but gets it's hot water from an outside wood burner. The flame unit has been turned off, so the controller for that and the chimney damper has no affect.
So....can I do a temporary by pass? Turn all zone valves to manual override. Then disconnect the Taco pump from the controller box and direct feed 120 V to the Taco pump.
I think that would safely work until I get the more desirable automatic feature of the controller operational.
Any suggestions?

[mrcaptainbob]

The thermostat wires are daisy chained across all four end switches. One of them, #4 had a hot wire that was off the terminal. No reason, as nobody me goes into the basement. well, I touched it to it's terminal and found a spark! Cleaned back some insulation and set it correctly in place and....THE WHOLE SYSTEM WORKS!! Can it be that simple????

[HayZee518]

L1, L2 is line voltage. C1, C2 is the capacitor wiring 120 directly into the motor may or may not work thermostats are annotated Th1 Th2 the daisy chained array forms a safety system for the system. disconnecting any will shut down the unit.

[mrcaptainbob]

Very interesting, HayZee. Thanks for that. Confirms what happened. It is suspicious as to why the one wire was off the one screw. Strange. I think I'll go over the whole system come warm weather and verify that all wiring has good contact. Thanks again, HayZee.