Hot water heat circulating pump issue

[Steven Fenton]

Hey gang,

I have an old house with a very modern (2008) combo on demand water heater and house heating water heater. I have two loops, an upstairs and a downstairs. Both run on the same 1/10hp circulating pumps. The one that runs the upstairs has worked flawlessly since installation, but I've had to replace the downstairs one twice now, and it looks like it's failed a third time.

What could be causing the pumps on one loop to burn out, while the other one hasn't had a glitch? It's not a big deal to swap out a pump, but if there's an underlying problem I'd like to fix it.

 

[hj]

What is failing? If it is the motor, then it is NOT a "circulation" problem.

 

[Sponsor]

 

[DougB]

What could be causing the pumps on one loop to burn out, while the other one hasn't had a glitch? It's not a big deal to swap out a pump, but if there's an underlying problem I'd like to fix it.

What is the make / model of the pump? Picture? Does the pump run all the time?

 

[Jadnashua]

On potable water, the pump must either be bronze or stainless steel...if it's a hydronic heating pump, it will have CI parts, and those will fail on a potable water system because of the constant influx of dissolved oxygen - they rust themselves to death. The bronze or SS pumps are generally a LOT more money.