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Thread: Check Valve on pool pump question

  1. #1
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    Check Valve on pool pump question

    Hello, Just installed a new Epump (1.5 HP) from jandy. My pool is 30K gallons and my equipment is located about 2 feet above the waterline. Jandy told me that I didn't need a check valve but my old .75Hp had one on the discharge side. The pump manuel states check valve on the suction side. Can someone point me in a direction. Do I really need a valve and if so where do you recomend? Oh before I forget, I already installed the piping with out it and have yet to run the pump.....Thanks in advance

  2. #2
    Mod Squad JohnT's Avatar
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    Re: Check Valve on pool pump question

    I don't know what purpose a check valve would have on the discharge side. If your pump can restart without being primed after sitting overnight, you probably don't need a check valve. If it loses prime, add a check valve on the inlet side.
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    Re: Check Valve on pool pump question

    Someone told me that if the check valve is on the discharge side it will prevent the water from the filter (DE) entering the pump chamber and causing damage to the impeller. Any thoughts??

  4. #4
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    Re: Check Valve on pool pump question

    Since you have plumbed without it, try it out. It is only there to make it easier for your pump to prime.

    You will lose prime each time you open the pump strainer basket because of the elevation of the equipment.

    I would guess your pump will pull that two feet just fine (probably on high) but, if it doesn't, you can always come back in and put the check valve in.....on the suction side.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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    TFTestkits , PoolMath , Pool School

  5. #5
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    Re: Check Valve on pool pump question

    What about the theory of the DE coming back into the pump housing from the filter? Will this cause a problem?

  6. #6
    Senior Member mas985's Avatar
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    Re: Check Valve on pool pump question

    Unless you have solar, I don't think that should be a problem. With the pump lid off, water will drain away from the pump and with the lid on, pump primed and off, water should never flow backwards.

    Also, a 2 foot prime should not be an issue for any pump.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  7. #7
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    Re: Check Valve on pool pump question

    My equipment is about 4 feet above my pool and as soon as I open the pump lid, the water gets sucked out of the pump basket on its way back to the pool as mas mentioned. I do have a check valve on the suction side (pb put it there) and I like it since it primes in seconds. I have a 2hp pump right next to it for the slide and it does not have a check valve. it takes over 2 minutes to prime after allowing it to drain.
    21k gal SW, IG Gunite PebbleSheen, 1HP Jandy, Jandy 340 filter, Polaris 280, 17' fiberglass slide w/ 2HP pump.

  8. #8
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    Re: Check Valve on pool pump question

    Quote Originally Posted by crabboy
    My equipment is about 4 feet above my pool and as soon as I open the pump lid, the water gets sucked out of the pump basket on its way back to the pool as mas mentioned. I do have a check valve on the suction side (pb put it there) and I like it since it primes in seconds. I have a 2hp pump right next to it for the slide and it does not have a check valve. it takes over 2 minutes to prime after allowing it to drain.
    Ouch 2mins! I was told by more than one pool store guy when i was fixing my pump problems that if you don't reach prime in 30 secs you will start hurting your pump. 2 mins is a long time to run dry. I bought 2 jandy check valves and am putting them on my two returns (skimmer and main drain) The instructions call for a min. of 18" of water above them so gravity can hold the flapper closed and sealed. This required me digging up the area in front of my slab. I decided since these are nice valves and $50 ea. I want to be able to look into the clear service window occasionaly so i'm installing them a few feet from the slab where the pipes go vertical and am putting a irrigation box with cover over them.
    The valves belong on the suction side to hold the water prime. Ive seen the valve on the output side and yes that will keep the filter from dumping as you open the strainer cover but thats why you should move your multi port valve/switch to off first. there should also be 2 valves the way i'm doing it. The other thing that happens with the valve after the pump is that if you don't close all the jandy valves on the suction lines before you pull the lid all the water will flow back to the pool and youve lost water prime.
    I've seen the one valve right before the pump and that's INCORRECTLY installed. you need a colum of water above the valve per the manf. instructions, requiring the valve placment be lower. Yes I know there is a nice spring in my jandy check valves I just bought but for $50 a pop I'm going to install it right.
    Another reason you shold have 2 is that if there is a leak in any of the suction lines than they can't communicate this leak between one another while the pump is off Like a one check valve setup would do.

    If you have the money put one check valve on each suction line before its jandy valve with 18" of vertical pipe above it
    (yes this may be below the dirt, pool builders do it too) AND put a check valve after the pump too.
    now you never have to touch the multiport or suction valve handles when you want to pop the top off the strainer and you won't loose any prime AND won't get the "filter flood" from the filter

    I appologise if this posts a bit ranty im curently working on my equipmet and have had a lot of priming headachces and learnig experiences as of recent becuse the lazy builder nerver installed ANY check valves on my equipment. Its 50-60 ft. from the pool and 6 feet above the pools water line, no brainer here, need check valves for pumps sake!
    20,000 gal. 32' x 17' freeform custom pool, 3ft. shallow - 8ft. deep end, Pentair Whisper flow 2.2 HP WF-6, Purex/Triton Nautilus FNS48 DE filter, 2 Intex Chlorine Generators (retired) SR Smith Rouge Rapids curved slide, The Pool Cleaner 4-wheel model w/Hayward large leaf canister. Tightwatt pool timer Spa: Beachport 5 person/350gal. Wishlist: move Neiko Tools pump to slide, solar system, Fountain, Automation. http://www.poolcalculator.com/

  9. #9
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    Re: Check Valve on pool pump question

    I have frequently run the pump 2 mins before priming.....no problemo to this point. (6 years) I wouldn't suggest five minutes but I know there are stories on here of people running dry for 30 mins with no damage. Again, I wouldn't suggest anything over 2 minutes but I think that's safe.

    My equipment pad is roughly 36-40 inches above pool level. Losing prime and getting prime is a major concern for me.

    My suction side line is approximately 40" above thewhere the line enters the pump, but the column of water within the system is at least 24" higher than that at the top of the filter. I don't understand the necdessity of digging a hole in the ground to obtain the 18" you suggest. Why wouldn't the water in the filter apply enough pressure to keep the check valve closed.

    Secondly, I don't understand why I would need to check valves. my suction side lines merge into one 2" pipe about 24" prior to entry into the pump. Why couldn't I just put one check valve there?

    I know you have done your homework but I'm having trouble following what you are suggesting. I will be installing a check valve in a week or so and I want to do it correctly.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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  10. #10
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    Re: Check Valve on pool pump question

    Hmm, I like your point about the water in the filter, If the multiport valve is in the normal "filter" position that would allow pressure from the filter to apply to a valve when the pumps off. The problem with this is that the check valve is there for a few reasons, Primarly it's to hold water in the pipe between the valve and the pool, when you take the cover off the strainer basket you will be opening up that area of water your relying on for the check valve. And you will first have to tuen the MPV to "off" to prevent filter back flow into and over the basket, I call the "Filter Flood". One could argue that now gravity is pulling on the column of water and hence trying to pull the Valve flapper more tightly closed...I'd rather follow the manf. recommendations. Another reason for the check valves is to isolate air leaks in the equipment from allowing the returns to empty into the pool overnight. With one per return now any leaks in the returns themselves won't affect the one next to it. THe jandy (manual) valves also become part of the equipment on the pad of isolation and If leaky won't cause a lost of prime in the return pipes.
    So it's a matter of how safe and sure you want to be. Armed with the knowledge in this thread we can each decide whats good enough for our equipment.
    20,000 gal. 32' x 17' freeform custom pool, 3ft. shallow - 8ft. deep end, Pentair Whisper flow 2.2 HP WF-6, Purex/Triton Nautilus FNS48 DE filter, 2 Intex Chlorine Generators (retired) SR Smith Rouge Rapids curved slide, The Pool Cleaner 4-wheel model w/Hayward large leaf canister. Tightwatt pool timer Spa: Beachport 5 person/350gal. Wishlist: move Neiko Tools pump to slide, solar system, Fountain, Automation. http://www.poolcalculator.com/

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