Cooling loop valve 2

[itsmoked]

I have a cooling system as seen below that runs water/ethylene glycol mix to cool 13 zones via solenoids.

The pump charges a manifold that the zones draw from. Since temp controllers run the valves none can be open or most of them can be open. All of them are never open though perhaps half could be at once.

I want to spec a valve to bypass when needed to try and keep the supply pressure constant thru the loops while also avoiding dead-heading the pump. I have no idea what the correct term for this particular valve would be or where I should look for one. Given the details I've provided can I get some direction on what and where I should get one, preferably at the usual suspects.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

If only.. The controller is a multi-rack PLC no one has access to. I'd make so many changes. If they build another from scratch I'd certainly control the bypass, heck, I'd probably go with a VFD.

Rputvin; Thanks I'll give that a try. We boil the water in the zones but back out in the return manifold I don't think it's much over that valve's temp rating. For that price it's worth a try.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[TugboatEng]

Working around locked out controllers is my specialty. In that case I suggest the NC relay route to open a recirc/bypass line when no other solenoid valves are open. Bring back the good ol' days of relay logic, but cheat a little bit with modern semiconductor technology.

 

[georgeverghese]

If you consider Tugboat's suggestion, then the bypass line solenoid should open when less than 7 cooling loop solenoids are open. Am assuming total operating demand is about 38gpm for 13cooling zones. Size / set the bypass solenoid valve line for 20gpm. And to minimise dead band cycling, you could say close this bypass line when 9 or more cooling loop solenoids are open. That will mean the max operating point at the pump will shift to 20+(9x2.9)= 46gpm at approx 41ft of head.
Compare this with 38gpm at 46ft of head at the pump if you could find an alternate self actuated backpressure - min flow bypass control valve sensitive enough to respond to small changes in demand.