Valve to redirect flow over specified GPM

[mvoltin]

I read somewhere but can no longer find the source or name:

There is a valve that allows certain GPM to go through and anything over gets redirected (bypassed). Here is a specific example:

If a heater can handle up to 10GPM but the overall system flow varies from 10-30GPM, valve (or something else) needs to let up to 10GPM through towards the heater and then redirect (bypass the rest of the water. So, the overall flow doesn't get reduced (it can be 30GPM) but the flow through the heater will remain 10GPM at all times.

Thank you.

 

[JamesW]

A spring loaded check valve will do this. The spring is set to open at a set psi.

For example, a Pentair R172305 check valve has a 12 lb (12 psi) opening pressure.

R172305Z | Water Bypass Check Valve

Water Bypass Check Valve

www.getpoolparts.com

You would put the check valve on a bypass line and the check valve will make sure that there is not more than a 12 psi differential between the heater inlet and outlet.

You would look up the heater head loss curve and see what pressure corresponds to the flow you need.

R172305 - UltraTemp Water Bypass Check Valve - 1.5 Inch Socket - Pentair

This is a Pentair Water Bypass Check Valve, 1.5 inch socket, with a 12 pound spring for UltraTemp Heat Pumps. This check valve is also designed for the Thermaflo Heat Pumps.

www.poolweb.com

The above check valve is used in the Pentair heat pumps.

Here is a 5 psi check valve.

American Granby Inc. 2" PVC 5lb. By-Pass Flo-Control Spring Check Valve (#1095-20)

American Granby Inc. 2" PVC 5lb. By-Pass Flo-Control Spring Check Valve (#1095-20)

www.4guyspoolsupply.com

For example, if you had an Ultratemp 140, you would look in the manual for the flow requirements:

Flow Rate: Maximum 120 gpm [456 lpm] - If system flow rate exceeds 120 gpm, a bypass valve is required. Minimum 30 gpm [110 lpm]

https://www.pentair.com/content/dam/extranet/pentair-pool/residential/manuals/heaters/ultratemp/ultratemp-heat-pump-installation-and-users-guide-en-fr-sp.pdf

The heat pump already has a check valve bypass, but if you wanted to install an external bypass, you would check the Heat Pump Pressure Drop graph on page 26. If we use a 5psi check valve, it will not open until the flow through the heater reached about 41 gpm.

So, a 5 psi check valve would be a good choice for this application.

 

[mvoltin]

Thanks tons, James. This is exactly what i was looking for and explanation of head loss helped a lot (I am new to this).