Reading this guide will help you replace a top mounted Multiport Valve (MPV) on a Hayward sand filter. Some of the reasons for replacing a MPV are cracks in the valve's body or the top assembly, internal components failing like a spring or o-ring. Many of the internal components may be replaceable, but if your MPV is old, it might be time to replace the whole valve.
1. TURN OFF PUMP - Make sure the power to the pump is shut off before replacing the MPV.
2. VIEW PLUMPING (AG POOL) - The first step in replacing an MPV is to remove the plumbing to the MPV's intake and returns ports. For an Above Ground (AB) pool, the plumbing typically consists of flexible pipes clamped onto screwed in fittings. This plumbing is generally easy to remove.
3. REMOVE TUBING - The flexible pipes are usually clamped on. Remove the clamps and pull off the flexible pipes.
4. REMOVE FITTING - Unscrew the fittings in the two ports. They will turn counter-clockwise. Go to Step 6.
5. VIEW PLUMBING (IG POOL) - If you have an in-ground pool, your piping to the MPV will probably be rigid PVC. If you had unions installed, you can simply uncouple the unions to remove the fittings from the MPV ports. Without unions, you will have to cut into the piping to remove the fittings. This would be a good time to install unions for the next time you need to service the MPV.
6. UNSCREW CLAMP - This MPV is held onto the filter with a clamp. Remove the two screws that secure the clamp to the filter.
7. REMOVE MPV CLAMP - Remove the two-piece clamp.
8. REMOVE THE MPV - Gently pull the MPV off of the standing pipe inside the filter and continue to lift the MPV up off the filter. Be careful not to lift the standing pipe and attached laterals out of the sand when you separate them from the MPV.
9. INSPECT NEW MPV - Before placing the new MPV on the filter, inspect the MPV O-ring at the base of the MPV for any damage. Then lubricate the O-ring with a silicon or Teflon lubricant.
10. PLACE NEW MPV ONTO FILTER - Slip the MPV onto the standpipe inside the filter. Once in place, the MPV should sit snuggly on top of the filter. Gently rotate the MPV to where you can easily read the pressure gauge.
11. REPLACE THE CLAMP - Replace the MPV clamp and secure it with the two bolts.
12. REATTACH FITTINGS - Screw the two fittings into the MPV ports. Normally, you would wrap two or three turns of Teflon tape on these fittings before attaching them.
13. REATTACH HOSE - Press the flexible hoses onto the two fittings and secure them with clamps. For an in-ground pool with rigid PVC, reattach the fittings with unions.
14. LAY OUT WASTE LINE - Remember to attach and lay out a waste line from the WASTE port of the new MPV. Also, check that the sight glass was installed by the WASTE port.
15. YOU'RE DONE - You have successfully replaced your MPV.
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