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Thread: Which type of booster pump?

  1. #1

    Default Which type of booster pump?

    I am boosting my muni water pressure( presently 25-30 PSI). I have a finished basement. I have 2 choices of equipment;

    A Grundfos MQ constant flow (quiet , but would go on / off alot) , and a Gould
    J5S jet pump with 20GAL pressure tank. This unit is rather loud.

    Would the Grundfos last as long as the Gould setup and much electricity usage differences. If the Gould would be better , I would have to put some soundproofing around it.
    The system would be installed in the unfinished part of the basement.
    Thanks for your help and valued opinions.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    "This Old House" installed one during this season for a customer...you could probably find the details on their website. You need to verify that your flow is adequate so you don't starve the pump or you'll ruin it.

    Functionally, you are emulating a well system with a storage tank. The larger the tank you select, the fewer the on/off cycles you'll need, but it might have the same issues as with a well control...the pressure would cycle between the high and low settings.

    A flow-controlled pump that ran continuously when it detected flow might give you more consistent pressure, but would likely cost more...it also might not last as long since it wouldn't be on that long if you were say brushing your teeth.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Moderator valveman's Avatar
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    The Grundfos MQ has a water cooled motor, an electronic pressure switch, and a built in pressure tank that is smaller than a baseball. The water cooled motor makes it more quite but, minerals in the water can build up in the motor and eventually lock it up. The electronic pressure switch is not as dependable or long lasting as a standard mechanical pressure switch. The baseball size pressure tank means the pump comes on every time you wash your tooth brush or fill an ice maker. A small leak such as a "forgot to giggle the handle toilet", or a dripping faucet can cause this pump to cycle on and off rapidly. This will cause the electric bill to be extremely high but, not for long, because it will shortly destroy the pump.

    The Goulds pump has a air cooled motor so the fan makes more noise. You can't cover it up completely because it needs air movement for cooling. The 20 gallon pressure tank has 5 gallons of usable water, so the pump does not come on every time you wash a tooth brush. The mechanical pressure switch is cheap and long lasting. Adding a Cycle Stop Valve will eliminate cycling which makes the pump last longer, gives you constant pressure, and reduces the size of tank needed. With the CSV, you don't really need 5 gallons but at least 1 gallon storage is a good thing.

    Grundfos also makes standard jet pumps like the JP5, which are good pumps. They push the MQ because it's life span can be more accurately controlled. "Planned obsolescence" means they know how often you will need to replace the pump, which is better for their cash flow.

    It would probably be better to use a 3/4 HP so you can run at 40/60 pressure no matter how low the incoming city pressure drops.

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  4. #4
    Moderator & Master Plumber hj's Avatar
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    Default pump

    Good picture, but I would install a bypass line with a check valve between the pump inlet and outlet. That way, if the city pressure should be adequate the water will bypass the pump so it would only need to operate when necessary.

  5. #5

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    Thanks for the detailed info. I really appreciate it. I am leaning towards the Gould system. They do install a bypass valve to bypass the system.
    I was thinking about a small soundproof wall surrounding it , and also allow air cooling. Trying to keep the sound to a minimum ,to the finished basement.
    Criteria; Quiet, efficiancy, and reliability .
    Thanks again.
    Ted

  6. #6
    Moderator valveman's Avatar
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    A bypass line with a check valve, and ball valves before and after the pump system, are good ideas. This way you will still have water if you ever need to take the pump out for repair. However, the water will take the path of least resistence, so the flow will basically be split between the bypass line and the pump system line, even when the pump is off. Water flowing through the pump doesn't really hurt anything unless it is enough flow to spin the pump and motor. Then you get electrical regeneration from the motor which is not a good thing.

    As long as the city pressure stays higher than the setting of the CSV, the CSV will stay in the 1 GPM position, and only allow 1 GPM to flow through the pump. The remainder of flow being used will then travel through the bypass with check valve, and not cause the pump to spin and cause regeneration. Without the CSV, flow is split between the bypass and the pump system, which could be enough flow to spin the pump and cause regeneration problems.
    Last edited by valveman; 02-05-2009 at 06:05 AM.

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