Noisy Check Valve

[Marshy]

I have a check valve in my system that is wicked noisy occasionally. It seems the faster I run the circulator the higher chance it will make noise. I say it like that because some times its quiet when on medium or high speed and other times it's very noisy. See the below check valve circles in the diagram.

For example, none of the zones are calling for heat, boiler jacket is 180F so it's only load is to charge my Solartechnics tank. I have to shift the circulator into medium or high speed to keep the boiler from entering idle mode when the top tank temp is nearing 170F. I can run it in high speed for a while and no noise then all sudden the check seems to start chattering.

Any ideas? I know the placement of it is likely the cause because the Tee is probably causing turbulence. If I could somehow get the air out of the top of the check valve would it help?

 

[Marshy]

 

[salecker]

Hi Marshy
I see a double check valve arrangement in your picture.
Did you build the system? If so,or do you know the theory about that setup?
When i built my system i was told to add the same thing,at the time i never asked why.I knew very little about hydronics so i just did what i was told.
Or if anyone knows what it does?
I have found my check valves will make noise if my water level gets down a bit.I was just shy of enough expansion room for the first couple of years.So i would add water in the fall at startup and would always lose some once the system was up to temp.

 

[Marshy]

Hi Marshy
I see a double check valve arrangement in your picture.
Did you build the system? If so,or do you know the theory about that setup?
When i built my system i was told to add the same thing,at the time i never asked why.I knew very little about hydronics so i just did what i was told.
Or if anyone knows what it does?
I have found my check valves will make noise if my water level gets down a bit.I was just shy of enough expansion room for the first couple of years.So i would add water in the fall at startup and would always lose some once the system was up to temp.

Yes, I built the system per the recommended drawings from Tarm to connect the Froling boiler to my Solartechnics tank. It allows the heat exchanger in my tank to work in a counter flow manner when adding heat or removing it from the tank. When charging the tank hot flows from the boiler and enters the top of the heat exchanger and when no boiler is firing and a zone calls for heat the cold flow enters the bottom of the heat exchanger maximizing differential temperatures.
The double check valve arrangement allows for that to happen.

I have an automatic makeup valve connected to my expansion tank.

 

[TCaldwell]

I believe the double checks are spring loaded and the single is a swing check? I’ve seen the spring loaded ones chatter at the times you have described, I believe the spring is too strong for the flow, I replaced with a spring check and no more noise.

 

[Marshy]

I believe the double checks are spring loaded and the single is a swing check? I’ve seen the spring loaded ones chatter at the times you have described, I believe the spring is too strong for the flow, I replaced with a spring check and no more noise.

The ones on the top left are in-line spring loaded and I have no noise from them. The one amt top center is a swing check and is the culprit. The Tarm diagram called for a weighted swing check but I could not find any.

 

[TCaldwell]

Maybe then you could replace the swing with a spring check valve? Nice work by the way!

 

[E Yoder]

I've found even some spring check valves can chatter. Some have support on both ends of the shaft (those are quiet), some have support only on one end and those wobble.

 

[Bob Rohr]

Probably way oversized for the flow rate it sees. If you don't have adequate flow the disc inside just flutters around. Ideally a check valve is sized to the actual flow rate its will see. The Cv number on a check is in the full open position.

Also swing checks are often a metal to metal seal, those spring checks probably have soft seats, either the disc or seat is teflon or EPDM.

One last note, swing checks need a pressure differential to close and seal tightly. In a closed loop hydronic, when no flow is present the pressure is the same on both sides, so even a small flow will cause the disc to move around. The application for a check like that would be a sump or well pump, air compressor, where you have a pressure difference to close and seal.

They get used on wood burners so they can open easily and allow thermo siphon.

Often times a check can be one, maybe two sizes smaller that the pipe size.