# Humming indirect water heater



## Eric3950 (Mar 16, 2012)

Hi everyone, I did post an intro a while ago,I am a licensed Master plumber in Nh and still learning everyday, any input here would be greatly appreciated. Believe it or not this is happening at my own house, I replaced my indirect with a 40 gallon Amtrol about 2 weeks ago, I started noticing a humming sound like a tuning fork when the tank is heating. I have 3 zones with zone valves and one circ, the wh is on priority. It is def coming from the hydronic side not the potible side. There is a ball valve on the purge and no stop an waste valves, whats funny is... when it is happening if I manualy open another zone valve the sound goes right away then close and it comes right back.....thinking of changing pump then zone valve... any other ideas?...Thanks


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## Plumber patt (Jan 26, 2011)

Sounds like it's your zone valve. I had a similar situation a few months back. We had a zone valve that gradually opened slowly and it would hit a sweet spot where it would make a noise... Almost like a high frequency type noise. We adjusted how much it closes and it's been fine ever since


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## ZL700 (Dec 8, 2009)

Zone valves for indirects are not a good idea. They restrict the flow and lower the indirect recovery capabilities. This will also cause the harmonics. You dont mention which brand valve but thier internal ports are usually small designed for smaller heating circuit loads. Indirects on priority work best with a proper sized circ dedicated to it.


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## rjbphd (Feb 5, 2010)

What brand zone valve is it??


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## Eric3950 (Mar 16, 2012)

It is a taco zone valve


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## rjbphd (Feb 5, 2010)

Eric3950 said:


> It is a taco zone valve


 Not helping much... Taco Sentry or the 571 valve? What size pipe and pump?


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## Eric3950 (Mar 16, 2012)

Taco 571.. so instead of paying for a new zone valve I removed and installed a Grundfos circ with an internal check , I have a taco exp.. so I wired the pump thru the dry contacts and so far the sound has gone away. Im thinking the zone valve was defective , around here there are tons of boiler mates on taco 571, but I agree the circ is better.. Ill keep u posted and thanks for the input


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