balancing valves on supply or return?

Brad S

Is there a benefit to having the balancing valves on the return manifold rather than the supply manifold for a radiant slab?

rreid

balance valves return


has to do with the the life of the mva in that it has
to work harder to open and close on the supply side

Tom Anderson_2

It makes no difference whether the balance valve is on the supply or return. The traditional practice is to put them on the return side, but there is no technical hydronic pressure reason to do so.

As far as making it "easier" for the control valve by putting balance valve on return, that is incorrect.

The only thing the control valve cares about is the difference in pressure *across* the control valve. Balance valve position has absolutly no effect on control valve... the DP across control valve will be the same, regardless of balance valve position. Remenber, when the control valve wants to close, when near shut off, there is almost no water flow, and with little water flow, the DP across the valve is at it's highest, indepndent of balance valve location. In this condition, there is almost no DP across the balance valve since there is almost no flow. The balance valve does nothing when there is little flow near control valve shutoff.

I've seen hundreds of balance valves installed on supply side working very nice. Also, control valve will work equally as well on supply or return side.

THP

Balance Valve

If you place the balance valve on the return after a control valve and it has a set of ports to check differential pressure you can use it to find a wealth of information. Such as pressure drop of the piping in that zone, what the return pressure is, actual flow in the zone, what the flow is with other zones on, supply pressure at that point and etc.