Circulator Pump Noise - See Video

[YamiLionheart]

Hey all, first time poster here and relative newbie when it comes to boilers. I've replaced a zone valve head on my own before so not completely in the dark.

My issue is with a taco circulator Pump that is making noise. Seems to only make the noise when the upstairs zone (zone 2) is not calling for heat but one or both of the other 2 zones (zone 1 and 3) are. See the linked video for an example of the sound and how it goes away when zone 2 opens up.

 

[Dana]

That could be mild cavitation at the pump impeller from flow that's too restricted. When all zone valves are open the pressure across the pump is lower than when it's pumping into the lower head of all three zones being open. Sometimes raising the system pressure a few psi can reduce it (not usually) but anything that's restricting flow on the zones can contribute to a cavitation or recirculation problem at the pump. Any partially closed valves on the zone plumbing, or a zone valve that isn't fully opening can contribute to a low-flow problem.

If the pump is nearing end of life (it's life can be severely shortened if it's cavitating constantly & heavily) it's probably worth swapping it out with a VR1816 set up for constant pressure. It's an expensive pump (~$180-200) , but it'll use 10% of the power than another Taco 007 ($75-90) drawing only the amount of power necessary to maintain the pressure. So when only one zone is open it's barely sipping power, but will step up to provide more flow when another zone valve opens up. It'll pay for itself in lower power use over it's life time, and the whole system will run quieter.

The ECM pump motor itself is ~80% efficient compared to ~60% efficient on the -007, and fact that it modulates the power down to only what is needed is what makes for the drastic reduction in power use.