Return pump from one zone mixing...

mstrbill

I am planning on installing a circulator on a return line from a large unit fan coil in the hopes of zoning it from the main system [ a hydronic system in a school with 2 large base pumps] . My idea is to promote flow through the fan coil when the big pumps are off and shoot 190 degree water to that coil only. The problem i  am asking for help on is  that when i do this how to avoid mixing with other returns cooling down the boiler water as it moves towards that one zone i am making flow in on the return side. I would like to do this with no extra check valves etc. The zone pump will be near the boiler and its supply piping is near the boiler , but tapped off the main line with other pipes to the school. The return line where the pump shall go is near the boiler and has the same tapped lines from other zones near it.

I am hoping that when the pump starts that only the boiler water will try to get to that zone and not much mixing will occur from the other returns near by. I would like to keep it simple with no additional valves , checks, etc. What do you all think. ????

Ironman

Probably not gonna work

You're not gonna get it to work without check valves. You'll also need a control strategy that prevents the zones from running simultaneously if you don't want return mixing.