Check Valve

[Schnozz]

Just connected my new (from a 2017 purchase) Pentair 2HP/2SP Pump & 150sqft Cartridge Filter PNCC0150OP2160 to the rigid PVC plumbing. Pentair supplies and the assembly instructions add an inline check valve at the outlet side of the cartridge filter. It simply slips into the outlet of the filter before the union attaches. I understand it prevents back-flo into the filter. I know what a check valve does, but what's the purpose in this case? What does it do for the system??

Thanks, Bob

 

[ajw22]

When the pump is off it prevents possible back flow through the filter that can occur under certain conditions.

 

[Schnozz]

Thanks ajw22.
I understand what the check valve does in that location. It prevents water backflow from the pool return run into the filter when the system is off. Any idea why that's needed/necessary for an above ground cartridge filter? I'd like to know why the check valve is a part of the system. If I can understand why it does what it does, I'll be able to troubleshoot any problems relate to the check valve if it ever fails.....Maybe it's just a Pentair specific safety feature....

 

[bioguy]

Hi @Schnozz . My guess is it is there because backwashing cartridge filters can damage them. In my agp setup, I don't have a check valve there, so I think it is not actually necessary. 3 pipes go into my filter. One comes from the pump, one goes back to the pool and one drains. I can get backflow through the filter if I close the valve from the pump, forget to close the one that goes back to the pool and open the drain.

 

[ajw22]

It prevents water backflow from the pool return run into the filter when the system is off. Any idea why that's needed/necessary for an above ground cartridge filter?

Because the water level is above the pool equipment. If the pool equipment was above the water level there would be less chance of water backlfowing when the pump is off.

I'd like to know why the check valve is a part of the system. If I can understand why it does what it does, I'll be able to troubleshoot any problems relate to the check valve if it ever fails.....Maybe it's just a Pentair specific safety feature....

Pentair does not know exactly how the filter will be used in what configuration. The CV may help and does not hurt if it is not needed so Pentair includes it as standard. It keeps Pentair from getting complaints about the way the filter operates if the filter is installed where a CV would help.

 

[Schnozz]

Thanks to you both... ajw22 and bioguy. Both of you make sense. I can rest easy...

 

[Schnozz]

So, I'm getting ready to start-up the system for the first time. Should the return side valves be closed before priming the pump the first time, or should the return valves be open?? The start-up instructions if there is a problem pressurizing the system for the first time I should immediately shut off the pump and open the return valves to relieve pressure.

1. Open the High Flow™ manual air relief valve until it snaps into the full open position (this only requires a quarter turn counterclockwise). Opening this valve rapidly releases air trapped in the filter. 2. Stand clear of the filter tank, then start the pump. 3. Close the High Flow™ manual air relief valve after a steady stream of water appears. 4. The system is not working properly if either of the following conditions occur. a. A solid stream of water does not appear within 30 seconds, after the pump's inlet basket fills with water. b. The pressure gauge indicates pressure before water outflow appears. If either condition exists, shut off the pump immediately, open valves in the water return line to relieve pressure, and clean the air relief valve, see Section F. Cleaning the High Flow™ manual air relief valve. If the problem persists, call (800) 831-7133 for assistance.