Waterway - 53 mm Fat Gasket for Pump and Heater Unions - 711-4020

Waterway – 53 mm Fat Gasket for Pump and Heater Unions

The Waterway 711-4020 is a 53 mm fat gasket, a replacement union gasket for spa pumps and heaters. It is 6 mm thick, and that thickness is the key difference to thinner union gaskets, so check it carefully before ordering.

Where to use this union gasket

This gasket can be used on pump or heater unions. It is often useful when you replace an old hot tub pump with a slightly different model, for example, because the new connections may not sit exactly like the old ones.

If you are renewing a pump union or a heater union and need a gasket with a 53 mm inside diameter and a 6 mm profile, this is the Waterway part to look at.

Dimensions of the 711-4020 gasket

The size is what matters with a union gasket, so compare these figures with your old gasket:

• Inside diameter: 53 mm
• Outside diameter: 74 mm
• Thickness: 6 mm

The thickness is the dimension most often overlooked. A gasket that is thinner or thicker than the original can change how the union closes, so match all three measurements.

How to choose the right gasket

Remove the old gasket from the union and measure it with a ruler or calliper: the inside diameter, the outside diameter and the thickness. Measure it flat and without stretching it, as an old gasket may have been compressed over time.

If your old gasket measures 53 mm inside, 74 mm outside and 6 mm thick, the Waterway 711-4020 matches those figures. If your measurements differ, this gasket is not the right one, so do not assume that a similar looking gasket will seal in the same way.

Also look at the union itself. Make sure the sealing surfaces are clean before you fit the new gasket, so that the union can close evenly on the gasket.

Replacing a pump or heater

When you swap a pump for a slightly different model, take the measurements from the new pump connections and from the pipework as well as from the old gasket. This helps you decide whether a fat gasket is what you need for the new setup.