Several years ago I fitted an NRV to part of the C/H system to prevent reverse flow when some of the TRVs shut, but it's always been very noisy (the valve rattles at about 500 Hz or so. It's installed vertically, with the flow from top-to-bottom. Is this just a duff valve, or is there a special sort of NRV that's designed for heating circuits?
Dave
In article , NoSpam writes
I use a swing check valve for this job without the problems you describe but it's only suitable for horizontal fitting or vertical with upwards flow.
About half way down this page:
How would you get reverse flow anyway?
Take it out and solve the problem?
Thanks, that looks like a simple solution.
I was surprised too. I have a 3-zone system with two rad circuits on one of the zones; when that zone's valve was off (but another zone was on) one of the circuits would still get slightly warm. I couldn't do an ideal common return point so I assume the circuit offered a return path to the "on" zone. An NRV solved the problem.
It seems that a swing check valve will do the job.
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