prime pool pump
priming a pool pump
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priming a pump
prime pool pump
prime a pool pump
priming a pool pumpr

Pool School Repair Archive

The Cache Pipe

Pool Prime RepairOne of the more exasperating chores in the pool business is priming a pump.

A simple reason is the ' pool professional ' who installed the pump didn't understand the importance of the cache pipe. The cache pipe is that vertical section of plumbing that exits the top of the pump.

To be efficient, the cache pipe must hold at least 2lbs of water to press out air caught in the vacuum- side plumbing. Using 2" pipe, that's about 9" and 1.5" pipe should be at least 2' long. (photo right) Only 6" of pipe added to this cache greatly eased priming.

Huh ?

To prime a pump, you fill the strainer basket (under the clear cover) with water. This water is your primer cache. Simply over-filling the strainer basket only sends a flood of water back to the pool through the suction- side plumbing on the front of the pump.

But you can maximize this cache (as much as the cache pipe will hold) by running a garden hose in the strainer basket and turning on the pump. When you turn the pump 'on', water is thrown up into the cache pipe and the spinning impeller holds it there in a vibrating mass.

Resecure the strainer basket lid and turn 'off' the hose. The strainer basket will look empty but that extra water in the up- right pipe adds weight to the primer cache. An impeller can't move enough air to blow out a birthday candle but this water mass is held in high, excited suspension, exerting an up and down pressure like a molecular hand pump.

Air bubbles up through this vertical cache because air is lighter than water. Nature abhors a vacuum so as air evacuates through the cache, pool water is towed along behind it. As soon as water finds its way to the strainer basket, the impeller picks it up and.....

we pumpin' ! pump priming repair

Two more things you can do to help a pump prime:

  • Apply pressure to the vacuum- side of the system by opening one valve from the pool; either skimmer or vacuum. Wrap a towel or rag around the end of a garden hose like a scarf and hold it securely in the pool- side vacuum or skimmer fitting. This helps push air out of the line.

  • A garden hose connection on top of the cache pipe (use a clothes washer female X female hose connecter) can add up to 10 pounds of back pressure to the cache; depending on how dirty the filter is.

    And, one thing you cannot do:

  • Valve off the pressure- side plumbing to increase pressure on the cache pipe. When you close the plumbing, air has no way to escape and all motion stops.

    Learn something you didn't know before ? Pool School PRO has hundreds more lessons and tips for pool owners and pros, alike !

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