How to install Dual Flush Valve for 2 piece toilet?

This article will explain how to remove and replace a flush valve from a dual flush toilet tank of a two-piece toilet.
 
Please note that the images are for reference only. The product shown in this article may differ from yours, but the information below is still relevant.

If the Flush Valve Base is NOT damaged or there is NO leak between the tank and bowl, then you can install the Flush Valve body ONLY.

Follow one of the two instructions to remove and replace the dual flush valve component:

• To install ONLY the Flush Valve body (the mechanism without the base)
  1. Close the shut-off valve and drain out the water in the tank
  2. Disconnect and remove the existing flush valve body canister
  3. Replace with the new flush valve body canister
  4. Refill the tank and test for leaks and for the flushing function
      
• To Install the ENTIRE Dual Flush Valve (both the mechanism and its base)
  1. Close the shut-off valve and drain out the water in the tank
  2. Disconnect the refill tube and remove the existing flush valve body canister
  3. Disconnect the water supply line from the tank and remove the tank from the bowl
  4. Remove the flush valve base from the tank
  5. Install the new flush valve base to the tank
  6. Reinstall the tank to the bowl and reconnect the water supply line to the tank fill valve
  7. Reinstall the flush valve body canister and reattach the refill tube
  8. Refill the tank and test for leaks and for the flushing function

To install Only the Flush Valve body (Mechanism without the base):

• Turn off the water supply by turning the shut-off valve clockwise
  
• Drain as much water out as possible by pressing down the push button until water within the toilet tank is flushed out completely. Lift the tank cover and use a sponge or a cloth to drain out the remaining water in the tank.
  

• Remove the existing dual flush valve body canister by rotating it counter-clockwise to unlock it from the flush valve base. Then lift up the existing dual flush valve body canister.
  

• Insert the new flush valve body canister into the base and rotate the flush valve body canister clockwise to lock it into place.
  
  

• Reopen the water by turning the shut-off valve counter-clockwise to refill the tank.
  
• When the tank is refilled, verify if the water is filled to the level at the marked water line at the back wall of the tank. Adjust the water level if needed by turning the water level adjustment on the fill valve to move the float cup up or down to increase or reduce the water level in the tank.
  
• Press the push button down to activate the full flushing cycle. Verify if the toilet flushes and refills without issue and if the flush valve canister flapper seals well when the flushing cycle is completed.
  
• Check for any leakage at the fittings. Retighten or reconnect as needed.

To Install the ENTIRE Dual Flush Valve (both the mechanism and its base)

Complete Flush Valve (body canister and base)	Flush Valve Base Only

Step 1 - Close the shut-off valve and drain out the water in the tank

• Turn off the water supply by turning the shut-off valve clockwise
  
• Drain as much water out as possible by pressing down the push button until water within the toilet tank is flushed out completely. Lift the tank cover and use a sponge or a cloth to drain out the remaining water in the tank.
  

• Remove the refill tube from the flush valve overflow tube
  
  
   
• Remove the existing dual flush valve body canister by rotating it counter-clockwise to unlock it from the flush valve base. Then lift up the existing dual flush valve body canister.
  

• Disconnect the water supply line from the tank.
  
  
   
• Underneath the tank, unscrew the bolts that hold the tank to the bowl. You may need to spray them with some penetrating oil first before trying to loosen them.
  Remove the tank lock nuts from under the bowl rims. Reach in the tank with a long slotted screwdriver to keep tank bolts from turning while loosening nuts under the tank with an adjustable wrench. Remove tank bolts.
  
  
   
• Lift the tank off of the bowl and set it aside on a towel.
  
  

• From the underside of the tank, unscrew the lock nut holding the flush valve to the tank using a plumber's wrench. Then remove the flush valve base from the tank.