Check Valve placement?

JackW

I'm replacing the cast iron circs and flanges on my radiant heating system after having severe rust issues this year, as noted in my previous post, with two older single-speed brass circs. I'll have to find a match for the third circ online. The cast iron circs had check valves installed in them, and since the older brass circs don't, I'll have to install separate check valves. Where is the correct location for them? Is there any particular placement I need to be aware of, and do all three circs need them? Also, is the spring check valve the one I should use?

Thank you,

Jack

Larry Weingarten

Hi @JackW , I'd look at whether or not running one circ could induce flow through another pump. If so, than yes, that pump probably needs a check valve to prevent ghost flow. So look at how it's controlled and how pumps run. Does the pump through the heater run only when one of the other pumps is called to run? If so, you probably only need a check on each of the "distribution" pumps.

I like spring checks over swing checks as long as flow is adequate. The check should be far enough away from the pump so it gets smooth flow.

Yours, Larry

JackW

@Larry Weingarten The return circ runs when one of both zone circs turn on, so there are always at least two circs running at any given time when heat is called for. I have three spring check valves coming, and since all three of the cast iron pumps had built-in check valves and everything ran fine, I'll install them below all of the brass circs.

Thanks for your input.

Jack