Hydronic Heat & Tripping Breaker

[nibsey]

I've got what hopefully amounts to a simple question...

About three weeks ago I noticed that the circulator pump (BG-100 series) on my 35 year old boiler system was cycling on/off in short bursts, like 5 seconds at a time. If I recall correctly, I remember that the pump used to run the entire duration when the boiler was fired up, then remained on for a few minutes afterward.

The boiler has not been run in a couple of weeks due to warm spring weather. Last night was a bit chilly, so I turned up the thermostat only to find that the boiler wasn't kicking on (just total silence after the thermostat call).

I checked the circuit board to find that the breaker had tripped (its a dedicated breaker). So I turned it back on and the system fired up without delay, circulator pump and all. After running about 5 minutes, everything shut down again - the circuit had tripped.

I turned down the thermostat, and reset the circuit. All was ok. I turned up the thermostat and it clicked as usual. But then, I heard a loud click at the furnace right at the time the system would fire up, and the circuit was tripped again.

Is this possibly a symptom of a bad circulator pump motor? Are there any checks I can do to better diagnose the issue?

If it is the pump motor, do I replace just the motor, or switch the entire unit to a TACO 007 or something. Its a 2500 sqft house with 2 zone baseboard heat. Mind you, the place is for sale, so I don't want to spend a ton on a fix. I'm pretty handy, but don't want to open Pandoras box with this 35 year old boiler. Also, I don't think I have shut-off valves on both sides of the pump.

Thanks in advance for any advice/input! Jason

[HayZee518]

with the help of a helper watch the boiler as you reset the breaker to ascertain what is coming on and going off. the circulator comes off the main control board as does the burner pump and igniter. it helps to use a clamp around ammeter to see what is drawing the most current necessary to trip the breaker. without an ammeter its almost hit or miss or the process of elimination. disconnect the circulator wires first and reset the system and see what happens. Next disconnect the burner motor - of course the system won't fire up but at least you can see if the burner motor [would] blow the breaker and so on.

[nibsey]

I reset the breaker and stood next to the boiler to see what happened. Sure enough, I saw a big spark-like flash come from the circulator motor, and it blew the fuse. I'm assuming that means there is a short somewhere in the motor. It is definitely the pump motor that's shorting out the circuit. Unfortunately I can't see where the wires actually attach to the motor because they are inside a wire shield., so i cant see if they are touching or not. I assume not as the motor was installed years ago and worked fine until just recently. Is there any potential fix to the motor, or should I just replace it with a new one?

Thanks again for the reply!

Jason

[HayZee518]

you have two options here. replace just the motor or replace the motor and pump as an assembly. if you replace the motor you'll need to see how its coupled to the pump body. most have the centrifugal impeller and seal come as one piece. the splice box called the "dog house" is on the motor.