In The Swim Knowledge Pool: Multiport Valves
Pool Filter Backwash Valves
In swimming pool terminology, a multiport valve is a valve used to backwash a sand or DE pool filter. A multi-port valve has many internal ports (hence the name), and enables the pool owner to Backwash the filter with the turn of a single valve handle, instead of several. Other commonly used functions include Rinse to flush out any residual dirt after backwashing, and Drain to Waste, for vacuuming to waste or lowering the water level without backwashing. Recirculate is used when the filter is in need of repair - if you can't filter the water, at least you can circulate it.
Multiport valves fit only certain specific filters, and are not interchangeable among filter models or brands or filter type. Sand filter multiport valves can be either top mounted or side mounted, however DE multiport valves are only side mounted, or attached to the side of the tank. Sand and DE filter side mounted multi valves are not interchangeable, as the in/out pipes are reversed - top-in for sand filters, and bottom-in for DE filters.
Multiport valves are also available in 1.5" and 2" models which refers to the size of the pipe connections. 1.5" valves are used on smaller filters, and 2" valves are used with larger filter models, and on pools with 2" PVC plumbing, to provide for higher flow rates. Slide valves, also called push-pull valves, are an alternative side mounted valve for sand or DE filters that offer higher flow rates with less restriction, but only allow two functions, filter or backwash.
Multiport Valve Troubleshooting
Leaking out the Waste Port: A common problem with pool multi valves is that water may begin to leak out of the waste port, or can allow water to return to the pool unfiltered. To repair a leaky Vari-Flo valve, replace the spider gasket, the key assembly, or the entire valve assembly.
Broken Valve Handle: Valve handles can be replaced by tapping out the handle pin to remove the old handle. To install a new MPV handle, remove the key assembly from the valve body, and have a helper push down on the lid to compress the valve spring, while you tap the pin through the handle and stem.
Leaking around the Valve Handle: Vari-Flo valves often leak from failure of the pair of stem o-rings located just underneath the handle, causing water to ooze around the handle and spill over the edge. Replace the o-rings, or replace the entire key assembly, or the entire valve assembly.
Leaks around the Pipe Ports: Cracks from over-tightening pipe fittings into the valve, or using too much Teflon tape. Cracks can also be caused by rotating the valve while the pump is running or other water hammer effects. Replace the valve body, or the entire valve assembly.
Leaks where Valve Connects to Filter: Top mounted multi valves have flange gaskets and side mounted valves have union o-rings to seal the valve to the filter tank. Loose bulkhead nuts or flange clamps, or failing o-rings or gaskets can be the cause.
At In The Swim, are proud to present a wide selection of filter multiport valves for Hayward, Jacuzzi, Pentair, Praher and Waterway pool filters. If you need help selecting the correct valve for your filter (it can be confusing), please contact our pool product specialists by email or call on the phone at 1-800-288-7946.