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Thread: No pressure when in pool mode, but good pressure when in spa mode

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    AaronGo's Avatar
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    No pressure when in pool mode, but good pressure when in spa mode

    Today I saw that there was no water coming over the spillover from the spa into the pool, so I went ahead and cleaned the Jandy 340 cartridge filters for good measure. That did not help any. So I switched over to spa mode and that works just fine. There is plenty of PSI when in spa mode.

    When in pool mode there is no pressure on the filter PSI gauge, but there is plenty of pressure when in spa mode.

    The pump primes and operates as normal in both modes, so I am not sure why the PSI drops to zero when in pool mode. I would expect to see no pressure regardless of which mode I am operating in.

    I suppose there could be some sort of clog, but it would have to get past the basket filter before the cartridge filter and then past the cartridge filters.

    All my pool specs are in my sig, but please let me know what other info I can provide that would help.

    Thanks!
    18,000 gallon in ground, plaster - completed 6/29/12
    Jandy 340 sq ft cartridge filter
    Jandy variable-speed 2 HP pump
    Jandy LXi 400 heater
    Jandy Aqualink PDA-PS4

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    Mod Squad jblizzle's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Pictures of the plumbing?

    If there is no pressure in the filter, then there is no flow. It may be primed in that the pump is full of water, but it must not be moving.
    Jason, TFP Moderator
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    AaronGo's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    I checked the basket before the pump and in spa mode it fills up completely with water, but in pool mode there is very little water in the basket. So that indicates to me there is an obstruction somewhere before the basket. I doubt it's a leak as we have no trees to cause issues and I have not seen any evidence of leaking.

    My next step is to get someone to come out and investigate the line and see if there is an obstruction.

    Any other ideas to consider?

    - - - Updated - - -

    Here is the plumbing. The bottom is the inlet depending on if it's in spa mode or pool mode. Then the basket before the pump and onto the filter assembly.



    - - - Updated - - -

    Also, when the pump is priming in pool mode the PSI gauge on the filter goes up some, but after priming the PSI goes to zero and the basket has no water inside it.
    18,000 gallon in ground, plaster - completed 6/29/12
    Jandy 340 sq ft cartridge filter
    Jandy variable-speed 2 HP pump
    Jandy LXi 400 heater
    Jandy Aqualink PDA-PS4

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    Mod Squad jblizzle's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Sounds like a big suction side leak or blockage on the pool side.

    No way this should happen suddenly, Did you vacuum without a basket or something?
    Is the pool water level high enough?
    Weir stuck closed?

    - - - Updated - - -

    Is that a valve to the right of the actuated valve? It looks closed.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    AaronGo's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Quote Originally Posted by jblizzle View Post
    Pictures of the plumbing?

    If there is no pressure in the filter, then there is no flow. It may be primed in that the pump is full of water, but it must not be moving.
    But why would the pump be moving water in spa mode but not pool mode? It's as if in pool mode it cannot get a sufficient amount of water INTO the pump, so it's a "supply side" issue I would think.
    18,000 gallon in ground, plaster - completed 6/29/12
    Jandy 340 sq ft cartridge filter
    Jandy variable-speed 2 HP pump
    Jandy LXi 400 heater
    Jandy Aqualink PDA-PS4

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    Mod Squad jblizzle's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Side note, you should not be using DWV fittings like those sweeps.

    - - - Updated - - -

    After you stated that there was no water in pool mode, then it seems clear there is a blockage on the pool side.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    AaronGo's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    So this is the craziest thing. I switched between spa mode and pool mode a few times to take pics of the valve positions and then it started working in pool mode. So perhaps the priming undid whatever blockage was present. I should probably still get someone to investigate the line and see if there is some blockage.
    18,000 gallon in ground, plaster - completed 6/29/12
    Jandy 340 sq ft cartridge filter
    Jandy variable-speed 2 HP pump
    Jandy LXi 400 heater
    Jandy Aqualink PDA-PS4

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    Mod Squad jblizzle's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Or run water backward through the line yourself using a hose and a rag/DrainKing
    Jason, TFP Moderator
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    AaronGo's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Quote Originally Posted by jblizzle View Post
    Side note, you should not be using DWV fittings like those sweeps.
    What are DWV fittings? I did not install the system, so how can I address this?

    - - - Updated - - -

    Quote Originally Posted by jblizzle View Post
    Or run water backward through the line yourself using a hose and a rag/DrainKing
    How would I go about doing that?

    Do I tie a rag to the end of the hose and snake the hose backward from the pump basket as far as I can go? I have never done that before so curious what the procedure is.
    18,000 gallon in ground, plaster - completed 6/29/12
    Jandy 340 sq ft cartridge filter
    Jandy variable-speed 2 HP pump
    Jandy LXi 400 heater
    Jandy Aqualink PDA-PS4

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    Mod Squad jblizzle's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Drain/Waste/Vent ... there are not designed for pressure applications so they will not last as long as Schedule 40 PVC. You would have to cut everything apart and replace them which would be a hassle, leave it until it develops a problem.

    - - - Updated - - -

    Wrap the end of the hose with a rag put it into the suction hole in the pump. You do not need to push it in far, the rag is meant to try to seal the opening so you can generate pressure in the line.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Quote Originally Posted by jblizzle View Post
    Drain/Waste/Vent ... there are not designed for pressure applications so they will not last as long as Schedule 40 PVC. You would have to cut everything apart and replace them which would be a hassle, leave it until it develops a problem.

    - - - Updated - - -

    Wrap the end of the hose with a rag put it into the suction hole in the pump. You do not need to push it in far, the rag is meant to try to seal the opening so you can generate pressure in the line.
    I just used a couple of those to redo my output plumbing changing my pump. That was all I found in home depot for 2 inch size. I guess I'm going to have to cut them out eventually?
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

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    Richard320's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    When you are in pool mode, is the pump on high speed or low? What about Spa mode?

    It's not beyond the realm of imagination that the pump goes to high speed in spa mode to generate bubbles and stays on low in pool mode to save energy. And it's not uncommon at all for variable speed pumps on low speed to not register any pressure on the gauge. When you started manually overriding things, it might have gone to high speed.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    I guess I'm going to have to cut them out eventually?
    I don't think so. I have a different take on DWV fittings.

    They are not pressure rated like schedule 40 pvc which (I think) is about 180psi at 40C. Pool pressures don't come close to that.

    The glue surfaces on DWV are not as large. A schedule 40 glue joint may be 1.25" long.....a dwv glue joint is usually about 5/8"

    That said, I think if you are very careful and deliberate about the glue joints you make up, dwv will withstand pool pressures quite easily and never leak.

    No self-respecting professional would use them on most jobs because the cost difference is not that great but I think they are acceptable for a DIY guy.

    I've had a couple of dwv 90's on my pool for about nine years and they will bew there for another 50 years, I think.

    Others will have a different take.
    Dave S.
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    Mod Squad jblizzle's Avatar
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    I agree with you Dave. If they are installed, I would leave them as you will not likely have a problem. But using schedule 40 is industry standard I think, with higher margins, very similar head loss, and not much price difference.
    Jason, TFP Moderator
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    Re: No pressure when in pool mode, but good pressure when in spa mode

    Is the Actuator that controls the pool/spa valve turning all the way? That is, is it turning the valve close to 180 degrees from the spa position to the pool position? The Jandy valves are not very forgiving as far as position goes. The internal "door" or "partition" fully covers the internal port only for a few degrees of travel. I had one only about 8-10 degrees off that caused a leak. If off, you can adjust the internal cams to correct it.
    38000 Gal, IG, Plaster, 20' x 40' x 10', Attached Raised Spa, Intelliflo VS 3 HP (011018), Pentair Quad DE 60 Filter, Raypak (Rheem) 400,000 BTU (407a low Nox), Easy Touch 8 upgrade, Screenlogic 2 with wireless, IS-4 Spa Side Remote, Stenner 45MPHP10 w/15 gal tank, Intellibrite 5g (3), Dolphin Triton Plus robot with PRO remote, Water Tech Catfish handheld vacuum for spa, TF100 with SpeedStir.

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