Vent Hole in HTHW Check Valve

[steamdog]

Just curious about a specification I just saw. There is a control valve for a high temperature hot water heat exchanger (400 deg f at 400 psi design). They specified a vent hole in a check valve to be installed on the outlet side of the heat exchanger. Anyone know why?

 

[gxmplx]

I think it should read: "... vent hole and a check valve ..."

 

[willard3]

Two who are both guessing about this function.

Check valve and vent hole serve as a vacuum breaker for the HX. When HX cools down, shell will go below atmospheric pressure.....don't want to collapse the shell.

 

[steamdog]

Thanks, Willard3
I did not think of a vacuum breaker. I suggest them all the time on steam heat exchangers so the condensate can drain, but it makes sense on water, too.