Best Of

Swing checks sometimes get used as an over-heat protection valve on wood boilers. In this example the check is intended to stop reverse thermosiphoning.

Also if power goes out the hotter, higher buoyancy water will crack open the swing check enough to allow thermosiphoning. Same concept as a gravity hydronic heating system, movement caused by ∆T

So a swing check on an application with a thermal differential, may in fact not be checking.

Not an easy thing to calculate when a swing check cannot do it's job, really. A swing check really likes to see higher pressure on the downstream side to close and seal. A sewage lift pump is a good application for a swing check. High flow rate, can handle small solids.

If positive, bubble free check protection is what you want or need, go with a spring assist type check.

So that is why you want to know specifically what the check is expected to do.

Hi, Old trick was to drill a small hole through the disc to allow slow gravity flow, and just be happy. The amount of leakage through it on a hot water draw is not noticeable. But @Alan (California Radiant) Forbes , you have too many people relying on you, so you have to live forever, even if not with absolute efficiency. 😇

Yours, Larry