Reheat control valve on supply vs. return
Reheat control valve on supply vs. return
(OP)
Application - standard CAV/VAV supply air terminal box with hot water reheat:
I usually see the reheat coil's hot water control valve at the outlet (hot water return pipe) of the coil.
Occasionally I see a "rebel" design that has the hot water control valve on the supply line.
I've seen a similar post in the past, but coudn't locate it. Is there a reason for having the control valve on the return line, other than convention?
Thanks in advance for any feedback. -CB
(posted this also in valve eng. forum)
I usually see the reheat coil's hot water control valve at the outlet (hot water return pipe) of the coil.
Occasionally I see a "rebel" design that has the hot water control valve on the supply line.
I've seen a similar post in the past, but coudn't locate it. Is there a reason for having the control valve on the return line, other than convention?
Thanks in advance for any feedback. -CB
(posted this also in valve eng. forum)





RE: Reheat control valve on supply vs. return
The thread is Thread403-25360.
Regards,
RE: Reheat control valve on supply vs. return
RE: Reheat control valve on supply vs. return
RE: Reheat control valve on supply vs. return
The only place I can think of where this wouldn't be the best choice is on cooling tower bypasses. There is benefit to switching flow from the fill to the basin. The difference is that the cooling tower is a broken circuit exposed to air anyway, and the return side is designed with a substantial reservoir and static head. Even then, designs must give careful attention to ensuring that transient hydraulics don't empty or overflow the basin "cushion."
RE: Reheat control valve on supply vs. return
Go ahead CB, be a rebel.
---KenRad
RE: Reheat control valve on supply vs. return
RE: Reheat control valve on supply vs. return
This being said, I also put all of my control valves on the outlet of the coil. But it's been a slow day, and it seemed like a good idea to argue with tombmech for a while.
---KenRad
RE: Reheat control valve on supply vs. return
Of course, some people choose PVC for compressed air pipe, too.
RE: Reheat control valve on supply vs. return
Good Luck,
Greg Hansen