domestic hot water re-circ hammering

Jeff Zager

I have a water hammer problem with a re-circ system I istalled about 18 months ago. The tub valve in the most distant bathroom - ( a Am Std. R110 cycling type ) if opened to a certin position, will start a vibration in the entire piping system back to the HWT. I've replaced the PB
unit in the valve and that seems to help but not completly solve the problem. In so much as this is a low pressure part of the city I'm wondering if when the valve is operating it may be drawing from both directions of the loop and bouncing the check valve ? The hot water return takes off about six feet from this tub.

Sweet

Recirc

What type of pump/system are you using,does it still hammer with pump off.

Larry Weingarten

check valves

Not to jump to conclusions, but swing check valves can do just what you describe. Replace it with a spring check valve and things should get quieter. You could do a test fist by removing the flapper from the swing check to see if the noise is stopped. Another test would be simply to temporarily close a valve on the recirc line back by the heater and see if there is a change. Hope that helps.
Yours, Larry