Reverse flow in mix valve?

Terry

sounds like a missing check valve ?

KBP&H

Reverse flow

With a sparco 3/4 mix valve- can head pressure on the primary loop cause flow back yhru the mix valve, back out the cold side into the outerside to the boiler return, I know I can put in a pdv valve on the primary loop, but I'm trying to adjust the bypass ball valve to make up a slight pressure difference to still feed the two other zones on zone valves, with the szones closed it seems to push water back thru the mix valve, but w/ the zones open, it's fine,,, I have a larger systen to do w/ alot more 5 zones ( 3 w zone valves, 1 rad w/ circ & 1 baseboard w/ circ contro) that I plan to use a dpv on.

Weezbo

i agree. *~/:)

give it a choise of return...