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Thread: Converting Pressure Side Vac to Suction Vac

  1. Back To Top    #1

    Converting Pressure Side Vac to Suction Vac

    Hey all, another no0b with a question. Ive searched and saw a few pictures that seem to confirm my thoughts, but would like one last sanity check before I actually cut into the plumbing.

    Some initial specs for you;
    - The pool is 12 - 13k gal with a built in spa with overflow back into the pool (gallons are an estimate since I bought the house with the pool already installed).
    - The current pump is a 1.5 hp single speed.
    - The filter is a 190-cf Hayward cartridge unit.
    - The bottom feeder is a Jandy Rayvac pressure-side cleaner.
    - All plumbing lines are 2 ID except the pressure line to the cleaner which is 1.5 ID.
    - The equipment pad sits about 20 from the pool.
    - And the 3 way inlet valve providing water to the pump can restrict the flow from either the pool OR the spa but NOT both at the same time which is good. The same goes for the outlet from the filter its pool or spa but cant cut off both at the same time.

    Here is a picture of the current plumbing:

    Having told you all that, here is my plan: Replace the single speed pump with a Pentair VS 11018, replace the Hayward filter with Pentair 420 cartridge and convert the pressure side cleaner into a suction cleaner (probably for an MX8).

    Here is a stick diagram of what I would like to do:

    The 420 filter would now be sitting to the left of the return lines, which will allow me to move the pump further to the left also (approx. to where the current filter sits). From there I can cut the (what is now the pressure side to the cleaner) 1.5 line into the suction line and control it with a 2 way valve. My ultimate goal (as funds become available) is to add an actuator to the 2-way valve and set the timer to ramp up the pump and open the valve at the same time. After the bottom is vacuumed (time to be determined through trial and error) the valve would close and the pump would ramp down.

    Will there be enough suction through the 1.5 pipe to run the vac or would I need to restrict the flow from the pool/spa to get the required suction?

    I guess another option would be to have a 3-way valve for the vac. I would have to open the 3-way valve and rotate the innards so either the pool/spa line would be blocked or the vac line would be blocked but never both. Something like this:

    Which plumbing option would be best?

    Thanks much for any constructive criticism.


  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Converting Pressure Side Vac to Suction Vac

    Your second diagram is a much better idea. You probably will need to restrict flow from the pool to get enough suction through the cleaner line. However, you drew the three way valve for the cleaner in the wrong orientation. The connection on the three way valve that does not have a pipe opposite it should be the one that runs to the pump.

    The 1.5" pipe isn't ideal, but it will work without problems. The system will just be a little less efficient than it otherwise would be.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  3. Back To Top    #3

    Re: Converting Pressure Side Vac to Suction Vac

    Gotcha. I have plenty of room on the pad so I should be able to plumb that valve turned with the "inlet" towards the pump with little problem. I think it would be better than my idea of taking the valve apart. See, I knew there was a reason I asked.

    Im not too happy with the 1.5 pipe myself. I think they did that to get an added venturi effect for more water flow to the Rayvac jets. I could be wrong though. Other than doing some major digging Im probably stuck with it for my vac line. Living in a semi-desert I dont get too many leaves in the pool. Blowing sand is my biggest problem - Im hoping 1.5 will be fine.

    Im still open for suggestions, as I probably wont get to it until next week.

    Thanks for any help.

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