Hi I’m Vance and welcome back to Repair and Replace.
In this episode, I'll show you how to replace the diaphragm in a Delany Flushboy, Rex, or
Presto Flushometer.
To begin, you'll need a diaphragm assembly, a flat blade screwdriver, a smooth jaw wrench
and a cloth.
Flushometers or flush valves, are just automatically timed, self-closing valves.
At rest equal pressure water in the upper and lower chambers,
keeps the diaphragm closed tightly on the valve seat.
When the handle is pressed, the relief valve opens and releases water from the upper chamber,
which decreases the pressure.
High pressure water from the inlet now lifts the diaphragm up
and travels down the flush pipe.
During the flush, some of the water is forced back into the upper chamber
through a small bypass hole in the diaphragm.
The flush continues until the pressure equalizes,
and pushes the diaphragm down onto the valve seat.
The bypass hole size is extremely important for proper metering of water.
Continuous flushing can occur if the bypass hole is blocked.
If the bypass hole is enlarged, then the upper chamber will fill with water too quickly.
Alternatively if is the diaphragm or relief valve is worn down or sticks to the valve,
it can prevent the unit from even functioning at all.
First, shut off the water to the flushometer.
Remove the cap, and use a flat blade screwdriver to turn the screw clockwise,
until the control stop closes.
Next hold down the handle to remove any remaining water.
There might be some water inside so it's best to place a cloth at the base of the flushometer.
Use a smooth jaw wrench to loosen, and remove the flushometer cover.
Now remove the diaphragm assembly.
The flush volume is controlled by both the bypass hole size and regulating screw.
Diaphragms come in both urinal and water closet configurations,
so be sure to select the right diaphram kit.
If the guide assembly and relief valve are in good condition,
then you can just replace the diaphragm.
First remove the relief valve.
Next unscrew the bushing and remove the seat, and diaphragm.
Separate the valve seat from the holder, and then discard the seat and diaphragm.
Now slide the new valve seat into the holder.
Align the new diaphram and seat onto the guide.
Next hand tighten the bushing to secure the assembly.
Finally set the relief valve overtop.
Place the assembly onto the valve.
Now hand tighten the cap, and secure it into place.
Turn on the water, by opening the control stop.
Now test the flushometer and adjust the control stop until you get a normal flush with a quiet operation.
Now finally, replace the cap.
If needed, the regulating screw can be adjusted to fine tune the flush volume.
This will change how long it takes for the valve to reset.
Turning the screw clockwise will decrease the flush volume,
and turning the screw counter clockwise will increase the flush volume.
The screw is very sensitive, so start with a half turn and test the flushometer
until you get the desired flow rate.
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