How to Install Canister-Style Flush Valves

  A book about two people who had time‐traveled to the late 1700s contained this bit of dialogue: "What do you miss most about our time?" he asked. The woman thought for a moment, then gave the most honest answer she had. "Toilets that flush."

Who doesn't identify with that sentiment? The engineering marvel known as the flush toilet is arguably the fixture in a home that is most underrated and most taken advantage of — and the most missed when you don't have one (or you have one that isn't working properly).

What makes it all work is the flush valve, the part inside the tank that allows water to move inside the bowl. Essentially, after being triggered by the handle or button, the flush valve is what makes the flush happen.

The basic types of flush valves are flapper style (the standard in most toilets), ball style (not used as much these days, but they are still out there), diaphragm or flushometer (used most often in commercial buildings), and the canister‐style.

Regardless of the type, the flush valve's job is to allow water to go from the tank to the bowl in a way that will cause a complete flushing cycle: cleaning the bowl and removing its contents. It then replenishes the trap seal, which puts a certain amount of water in the bowl. (Incidentally, the trap seal is an especially important step, as it keeps the smells — sewer gasses and odors — on the other side of the trap seal. In all truth, this is what allowed us to bring toilets into the house.)

The specific type of flush valve a toilet contains depends on how it was designed, and whatever it was created with is what it uses. In other words, you can't upgrade your toilet from a flapper to a canister‐style. This is important to know when picking out a new toilet.

A canister‐style flush valve lets more water in more quickly than the others, which has its advantages and disadvantages. The faster you get the water into the bowl, the more power it has to clean. Unfortunately, this can also waste water. In some areas around the country, the device might require a larger pipe than standard flush systems, which can mean added expense. Check with your jurisdiction's building department to be sure about local plumbing codes.

Canister‐style flush valves were originally designed for one‐piece toilets, though now they're used in one‐ and two‐piece toilets. They've been around since the 1930s. Those older versions were more expensive, as they were made of brass and the seal holding the water in was made of leather.

Specific steps in replacing the canister‐style flush valve differs depending on whether the toilet is a one‐piece or two‐piece.

How To Replace A Canister‐Style Flush Valve for Two‐Piece Toilets

  • Step 1: Remove the tank lid and place it flat in the bathtub or shower on a large towel, to prevent possible breakage.
  • Step 2: Turn off the water supply to the toilet and flush the toilet to drain the tank.
  • Step 3: Place a large towel around the toilet bowl to catch any water that will leak, and then disconnect the water supply line.
  • Step 4: Remove the tank to bowl bolts and lift the tank off the toilet bowl; place it on the floor on its side.
  • Step 5: Remove the large nut on the bottom center of the tank.
  • Step 6: Remove the canister flush valve from the tank. The flush valve gasket should come with it.
  • Step 7: Put the new flush valve gasket onto the canister, insert the new canister into the hole in the bottom of the tank (making sure it is in the same position as the old flush valve), then tighten the nut on the underside of the tank.
  • Step 8: Install a new tank to bowl gasket on the flush valve threads protruding from the tank, and then insert the tank to bowl bolts.
  • Step 9: Place the tank back on the bowl, being careful to align the tank to bowl bolts. Use the proper tools to tighten the tank to bowl bolts, paying special attention so you do not crack the tank.
  • Step 10: Reconnect the water supply line and turn the water back on, then flush the toilet to check for any leaks and proper flushing. Make any necessary adjustments to the flush valve to achieve the best flush you can.
 

How To Replace A Canister‐Style Flush Valve for One‐Piece Toilets

  • Step 1: Remove the tank lid and place it flat in the bathtub or shower on a large towel, to prevent possible breakage.
  • Step 2: Turn off the water supply to the toilet and flush the toilet to drain the tank.
  • Step 3: Remove the flush valve retaining mechanism; some use three screws with offset lugs, some use a U‐bar to hold the canister in place, while for others you will twist the canister to release the plastic tabs.
    • For the screw and offset lug type, loosen the screws and rotate the lugs so they face the center of the flush valve, allowing you to lift the flush valve out.
    • For the U‐bar type, loosen the screw holding the U‐bar in the center of the flush valve until it moves side to side, then slide it to one side until the bar slips out of the hole and lift the flush valve out.
    • For the twist on/off type, you will need to push down gently and start twisting gently and increase the twisting pressure slowly to remove, so you do not snap the tabs off.
    • For the Kohler canister valve, normally the base of the existing valve does not need to be removed unless the seal is worn or is the cause of the leak. Remove the canister cylinder from the base by gently pushing down on the center shaft and turning counter‐clockwise a 1/4 turn to release the rod and then pull it straight up and out. The canister flush seal can now be replaced.
      If the flush valve gasket is worn and the cause of the leak, you will need to remove the base. To remove the base, push down on the base and gently twist until the tabs are moved in a position to release the base from the tank. The flush valve gasket should be attached and removed with the base.
  • Step 4: Install the new valve and flush valve gasket in the reverse order of the instructions for removing the type of valve you are working with.
  • Step 5: To install the new valve, apply some dish soap between the flush valve gasket and the flange of the base.
    • Align the tabs on the base with the corresponding slots in the tank.
    • Gently apply pressure to compress the flush valve gasket while turning the base until the tabs secure the base in place.
    • If your canister and base are in two pieces, align the canister cylinder with the base and insert the rod on the bottom of the canister cylinder into the slot in the center of the base. Gently turn the rod 1/4 turn clockwise to lock in place.
  • Step 6: Connect the trip lever chain.
  • Step 7: Turn the water back on, and then flush the toilet to check for any leaks and proper flushing. Make any necessary adjustments to the flush valve to achieve the best flush you can.

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