Why no check valve on the suction side before the pump?

[shagymoe]

I never see check valves on the suction side of the pump but if your inground pool is lower than your inlet pipes, when you take of the pump lid, water will flow back to the pool, making it harder to prime the pump or at least making the pump run for a few seconds without much water even if you fill the basket. Am I missing something there? Maybe these few moments don't really matter.

 

[Jimrahbe]

Moe,

If you want a check valve add one, but they are not really needed.

Pumps are designed to run dry for the minute or less it takes to prime.

A better place to put a check valve, or manual valve, is between the pump and the filter. This prevents the filter from draining back into the pool when you remove the pump lid.

Thanks,

Jim R.

 

[BMerrill]

Just turn the intake valves off (if you have any) before removing the pump lid.

 

[bradgray]

I never see check valves on the suction side of the pump but if your inground pool is lower than your inlet pipes, when you take of the pump lid, water will flow back to the pool, making it harder to prime the pump or at least making the pump run for a few seconds without much water even if you fill the basket. Am I missing something there? Maybe these few moments don't really matter.

We have them frequently in our area but they are only useful for equipment above the pool level.

A check-valve on the suction side of a flooded system (below pool level) won't do you any good. Gravity will overpower the spring and it will still flow into your pump as if it wasn't there.

Some pools have a diverter on every suction line (skimmer, main, cleaner). If this is you, as Billy suggested, just close them before you open the pump or filter.

If you have an "either/or" 3-way between your skimmer and main, you'll then need to change its rotation radius to close the outlet, or better yet, install another 2-way after the 3-way for the sole purpose of service work. Just be very mindful that you don't leave this closed when trying to run your pump or you'll quickly ruin your seals and eventually ruin your pump.

The check-valve will be helpful on your return after the last piece of equipment as Jim mentioned. To recap; you'll need both a diverter (intake) and a check-valve (return) to adequately seal the system from gravity-borne water when the loop is opened.

 

[JamesW]

A check valve on the suction adds head loss, which you want to avoid.

A check valve after the pump is a better choice.

Use a regular Jandy valve in front of the pump to close the line for service.

 

[Bill_WCL]

I never see check valves on the suction side of the pump but if your inground pool is lower than your inlet pipes, when you take of the pump lid, water will flow back to the pool, making it harder to prime the pump or at least making the pump run for a few seconds without much water even if you fill the basket. Am I missing something there? Maybe these few moments don't really matter.

My pool filter/heater are approx 3’ above my pool skimmer and spa suction lines. I have a pentair check valve in my pool suction line b4 my pump or it is close to impossible to get the pump to prime. Pool is gunite 36 years old.