Hayward Pump Mechanical Seal Replacement
WHAT IS A POOL PUMP SHAFT SEAL?
The shaft seal prevents water from leaking along the motor shaft, just behind where it connects to the impeller. The motor shaft goes through the seal plate, or the bracket that connects to the pump. The design of a shaft seal allows the shaft to spin without any direct contact (which would immediately cause a seal failure with the shaft rotating at 3250 RPM).
Shaft seals (#7) are composed of two halves, a round ceramic ring encased in rubber (what I call the Donut), and the other half with the spring, or the Spring Half. The donut usually sits in the seal plate (#3), and the spring half slips over the impeller (#8). As the impeller is tightened down, the spring half mates perfectly with the donut half, sealing up the shaft from water leakage, without actually touching the shaft.
WHY DO POOL PUMP SHAFT SEALS FAIL?
Shaft seals are constantly immersed in water, and although they are constructed of high grade stainless steel and chemical resistant rubber, chemical degradation can take a toll. Over time, near constant low pH or high chlorine will break down seal materials, and cause a shaft seal to leak. Ozone can also damage shaft seals, but not when installed properly.
Another cause of seal failure is running the pump dry, or nearly dry. With very little water running through the pump, the water inside gets very hot which can melt and warp some shaft seals. This usually happens from a loss of pump prime from low water level, stuck skimmer weirs or a large air leak in front of the pump.
A third cause of shaft seal failure is caused from a water hammer effect. This can happen if you start up the pump in spring without taking the return plugs out of the wall, or from closing a return side valve suddenly while the pump is running, or turning the multiport to backwash without turning the pump off first. This is known as a "seal blow-out", and that's exactly what happens, the seal cracks or becomes dislodged from the seal plate.
Available from our swimming pool shop in Pattaya or delivery to you