Do we have any plumbing types on TR?
On top of my gas water heater I have a Watts 1170-C thermostatic mixing valve to moderate the hot water temperature down. Unfortunately every time a tap is shut off it makes a "chunk-chink" sound - I suspect it is the mixing piston being driven across by the pressure spike. My water pressure isn't excessive, measured with a cheap gauge from Home Depot at about 75psi, and I've put water hammer arrestors on the washing machine outlets (the worst offender) but everything still causes it to make the noise. I know it is the valve and not just loose pipes because I listened to it carefully whilst my wife turned a tap on and off and also if I shut off the cold supply to the tank and mixing valve then it stops happening.
Is this just the valve going bad and I need to replace it? Or is this to be expected on this valve type? Worth trying a different manufacturer? Am I missing some pressure handling stuff in my plumbing setup to reduce the spikes or balance it across the hot and cold lines feeding in to the valve?