Spring loaded flow check?

[peakbagger]

Hi, I have a somewhat complex system with unpressurized storage, a wood boiler and an oil boiler. There are three heating zones run by zone pumps, two are plumbed up with 1/2" Hpex (I wish they were 3/4) and one with 3/4" copper. In certain situations, I get flow through the 3/4" zone without the pump on. There are some circulator pumps that serve double duty that are pressurizing the system on the supply side of the zones which is most likely the cause for the unwanted flow. I could wire in a zone valve in parallel with the 3/4" pump through a relay but that adds even more complexity to an already complex system. One alternative would be a spring loaded flow check that could be set up so that the pressure drop through the 3/4" zone is slightly higher than the 1/2" zones. I plan to do some pressure testign with manometers this weekend to figure out exactly how much pressure difference there is and possibly I may be able to swap some zone pumps around to increase the 1/2 zones pump head.

Anyone heard of such a thing as a flow check that can be preloaded?

 

[in hot water]

The spring type as well as the weighted flow checks generally have a 1/2 psi "pop" The only adjustable hydronic component would be a PAV pressure activated bypass valve.

Determine what the delta P is, eliminate it if possible. A small circ should only add maybe 4-6 psi, unless you start series piping them, of have a larger high head circ installed?

Or the zone valve option which typically close against 20, 30, 50, or 75 psi, depending on the cv of the valve.

hr