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How to replace a kitchen sink macerator Part 2

23 sept 2019


The macerator HANGS from the sink waste assembly, which is fitted separately and consists of 4 main metal parts plus 2 rubber sealing rings. To fit the waste assembly, insert the upper waste ring and spigot with top rubber gasket through the sink hole from the top. From the bottom, place the lower rubber gasket, the fibre washer, the metal backup flange and the mounting ring with 3 screws on the underside of the protruding spigot, under the sink. You have to screw up the screws to tighten the backup flange against the sink to make a seal.

To create a compressive stress the mounting ring has to react against something to load the backup flange. That something is the snap ring. You have to locate this ring in a groove and snap it into place. BUT at least one of your hands is occupied holding up the rubber ring, the fibre washer, the backup plate and the mounting ring! You need another pair of hands.

I only had one pair so some lateral thinking was needed. Got it. Place a heavy lump hammer in the sink on top of the upper waste ring, cushioned by a cloth to protect the ring. This holds the waste ring in place. Locate all lower items, in order, on the waste ring spigot and keep them in place with wadges of Blu-tackTM ! This left two hands to position the snap ring in the groove. Remove the Blu-tack, tighten the three bolts and thus make the waste seal, leaving the bottom of the mounting ring ready to accept the new macerator.

That mounting ring has three sloping attachment points positioned 120 degrees apart. The macerator has 3 lugs similarly placed. What you have to do, whether you feel like it or not, is lift the macerator up, engage all 3 lugs on the attachment points and rotate the macerator so that its lugs ride up the attachment point slopes and lock and seal perfectly.

They provide a wrench. It's hexagonal section to make you think you have to find allen bolts. You don't and it's designed to fool you. It's a LEVER that you locate in a socket at the top of the macerator to allow  you to turn it tight and make that seal.

Then it's just a matter of fitting the air switch actuator through the worktop (the new macerator didn't need a separate air switch) and connecting the air tube to the macerator, connecting the electrical supply through a new switched and fused spur and reconnecting the waste pipe and sink overflow.

Except now I have to get rid of the old macerator. I know. I'll feed it into the new one!