Swimming Pool Blog


Pool Filter Backwash Valves ~ Multiport Valve Care and Repair


by Sean Griffin, August 01, 2009

Multiport valves are used to direct the flow of water received by your pool pump. Multiport valves are upgraded versions of rotary valves and are also referred to as multi-position valve, vari-flow valve, and filter-control valves. A multiport valve has several positions that allow the pool operator to perform several different operations. Here's a description of them.

Filter position is used roughly 99% of the time during pool operation. When your multiport valve is set for Filtration, water is directed into the filter through the media and clean water is returned from valve to pool. The filter setting allows water to do just that, filter the water, in a Top toBottom direction through the filter tank.

Filter position is used roughly 99% of the time during pool operation. When your multiport valve is set for Filtration, water is directed into the filter through the media and clean water is returned from valve to pool. The filter setting allows water to do just that, filter the water, in a Top toBottom direction through the filter tank.

Backwash is the reverse or opposite of filter mode. The direction of the water is reversed. The water coming from pump will go through valve backwards, entering the tank at the bottom, and flushing out the dirt and debris that has been trapped in the sand bed. D.E. filters work the same way, the multiport valve reverses the flow of water through the filter to flush out the dirt and earth.

Recirculate allows water from pump to completely bypass filter and return to pool. This position is typically utilized when the filter is being repaired or waiting on parts. Recirculate allows you to run the  pump when you are having issues with the filter so your water will not become stagnant.

Rinse is used after backwashing sand filters. The water flow is similar to that of backwashing but it concentrates on flushing loose sand and/or particles out of plumbing to waste line. Using the Rinse setting for 15 seconds after backwashing, and before switching back to the filter mode, will prevent some sand and dirt from blowing back through the returns into your pool.

Waste or drain setting bypasses filter completely and directs water out of the backwash/waste line. This can be used when vacuuming out water that you do not wish to filter and return to pool. In retrospect it lowers the water level of pool and or spa.

Closed position shuts off all ports on the multi position valve and is utilized when doing a repair. When valve is closed all inlets and outlets are deadheaded and pump should not be run. Pressure build up can cause injury and/ or equipment damage. This position is used for valves that need to be free of water during the winter to prevent water expansion and equipment damage. The winterization position is often in between to settings keeping valve assembly slightly elevated to allow for ice expansion. If you don't have a winterize setting, place the valve handle in between two valve settings for the winter.

Common problems with Multiport Valves:

Multiport valves can fail or require repair for a couple of different reasons. Besides the obvious external damage that can occur, internal damage can be assessed and repaired. The most common issue with multi position valves is with the spoke or spider gasket.

The spider gasket creates a positive seal between positions on valve. Specifically, the seals the diverter (aka: rotor or diffuser) to the ports of the valve, preventing leakage from one port to another. If the gasket becomes dislodged, warped, or broken, the diverter will not seal and water will either escape out of the waste line or return to pool unfiltered.

Replacing the spider gasket involves removing the cover and key assembly and adhering a new gasket into the grooves in body of the valve. Use a small sharp screwdriver to be sure and get all the little pieces of the old spider gasket out of the groove before glueing in place the replacement.

Another common issue is a leak where lid connects to the body of the valve. This typically is the result of a bad lid o-ring. Another leak can occur in the center of the lid, and usually this means a problem with o-ring and or Teflon washer on stem of valve. Next to lubricating, the best way to resolve issue is to replace worn, broken, or damaged o-rings.

Most multiport valves utilize a spring to create tension and allow you to move through different settings and keeping a 100% seal. Over time, corrosion can affect the spring causing valve not to seat into correct position. If your handle is very floppy, with no tension, your spring may need replacement.

Maintenance & Operation:

Multi-port valves require no specific maintenance but there are a couple of simple things you can do to ensure the longevity of your valve. First and foremost is monitoring the water chemistry of your pool. Improperly balanced water can be corrosive and also weaken pool equipment. Test and adjust chemistry on a weekly basis.

Properly winterizing your valve will prevent freeze damage. Multi-port valves usually have a drain plug tapped into the main housing. Make sure to force air through valve allowing water to drain, when valve is water-free, leave in correct position according to manufacturer. Some valves have a specific winterization setting while other manufacturers recommend leaving in between two positions. I personally like to remove any backwash sight glass for the winter.

Whenever moving from one position to the next, make sure the pool pump is off. The water pressure entering the valve can damage internal components of valve if turned while the pump is running. It also can dead head your pool pump adversely affecting other pool equipment. Also when turning handle keep in mind this valve can become weaker over time and through use and that it can break under too much force. So, turn the valve handle purposely and gently from position to position.