Water Hammer coming through auto feed valve?

[MarkB]

Thanks in advance for the help...I've checked posts for this one but it seems unique because it involves both domestic water as well as my heating water. I'll attach a photo of the system.
When water is shut off anywhere in the house a loud banging is heard with what sounds like an echo. It also seems to happen when the furnace completes a water heating cycle. It seems to be coming from a furnace component. When I use the quick fill on the auto feed valve I hear the banging from somewhere within the components pictured. If I shut off the water supply valve to the auto feed the banging is still heard when water is used in the house. The banging no longer occurs when I close off the RETURN ball valve...it seems to solve all of the problem noises. I obviously can't keep the return to the furnace off. Could it be water pressure (hammer) flowing through the feed valve into the furnace system...the check valve located near the air scoop (due to the echo of the bang) or...???
Triangle tube Solo 110 condensing boiler with a smart 40 indirect water heater. There is an expansion tank attached to the air scoop (not pictured).
Pressure is usually at about 15 PSI.

[krow]

It really sounds like you may have an expasion issue, or your circ. pump is not pushing the water fast enough out of your heater

[MarkB]

It really sounds like you may have an expasion issue, or your circ. pump is not pushing the water fast enough out of your heater

Thanks krow. I did suspect an expansion issue...this morning I quickly shut of the supply valve (above the pump pictured) while the furnace was heating the house and I got the same bang...Any ideas or should I call someone in to evaluate?

[krow]

Thanks krow. I did suspect an expansion issue...this morning I quickly shut of the supply valve (above the pump pictured) while the furnace was heating the house and I got the same bang...Any ideas or should I call someone in to evaluate?

You should have a way to control when the circ pump kicks in. (it depends on how it is wired) .

If the pump has a delay before it turns on (usually a temperature setting on the low limit switch), you may want to lower the temp setting 10-20 degrees, this way the pump kicks in earlier. The idea is to get the hot water out of the boiler before it gets too hot.

' That may cushion the banging

[MarkB]

Hmmm...ok I can do that...it makes sense for the banging when the DHW heating shuts down... but the banging from water use/shut off throughout the house happens weather or not the furnace is hot or cold, or on or off for that matter.

[krow]

... but the banging from water use/shut off throughout the house happens weather or not the furnace is hot or cold, or on or off for that matter.

Are you suggesting that you have 2 sets of banging? 1 is not related to the other.

In this particular case, you can purchase 2 air chambers from HD or your local plumbing supplier and install them as close as possible to the faucet that is the noisiest. (I suspect that you have a faucet that shuts off really quickly). Install 1 on the hot line and 1 on the cold line (maybe underneath your cabinetry. ie: kitchen cabinet near sink)