How A Flush Tank Works

Nick — Thu, 21 Aug 2008 13:00:14 +0000

The mechanics of the toilet are straight forward and simple, and have changed very little since invented in the early 1800′s. There are two main parts to a toilet – the tank and bowl. The tank houses the working parts of the toilet, and works as follows (with accompanying illustrations from yours truly):

When the toilet is flushed, the trip handle lifts the tank ball (or rubber flapper or tilting bucket), opening the outlet and letting water flow into the bowl;
When the tank is nearly empty, the ball falls back in place over the outlet. The float falls with the water level, opening the water-supply inlet valve just as the outlet is being closed, and the tank is refilled through the filler tube;
Water flows through the bowl refill tube into the overflow pipe to replenish the water;
As the water level in the tank nears the top of the overflow pipe, the float closes the inlet valve, completing the cycle.

Ball Flush

Most toilet tank troubles in older toilets centers around the tank ball and its lift wire. The best fix is to replace the lift wires, guide arm, and tank ball with a rubber flapper which is anchored to the overflow pipe. When the toilet flushes, the tank ball gets raised by a chain fastened to the trip lever.

Flapper Flush

Problem	Solution
Water keeps flowing; tank does not refill after flush.	- Check to see if any of the trip handle, trip lever, lift wires or tank ball are bent. If they are and cannot be bent back into place, install a new parts. - Check seating of tank ball on valve seat. If not centered properly, rotate the guide arm on the overflow tube to reposition ball.
Tank fills, but water keeps flowing.	- Check to see if lifting float ball stops flow of water. If flow stops, bend float arm to lower the ball a bit.- If this fails, replace inlet valve washer by removing screws from inlet valve levers, disassembling and pulling out valve assembly.- If inlet valve seat is badly corroded, replace it. - If seat is not replaceable, then replace entire inlet valve unit. - Be sure bowl refill tube does not go into overflow tube below the tank water level. - Remove mineral scale on flush valve seat with fine wet/dry sandpaper. - Replace deteriorated tank ball.
Water level is too high or too low	- The water level should be about 3/4″ below top of overflow tube. Bend float arm down to lower water level, up to raise it. If level is too high, water will run over. If too low, there may not be enough water for a complete flush.
Tank flushes partially	- Tank ball may not rise enough to release the water in the tank. Shorten upper lift wire slightly and re-hook it through another hole in trip lever so that when the lever is depressed, the tank ball or flapper rises enough to let the water out.
Splashing sound inside tank during refill	- Make that the bowl refill tube ejects into overflow tube.- Flush and look for leak at inlet valve. If there is more than a trace leaks, remove valve and replace spilt O-ring seal or washer.
Tanks sweats	- Simplest method is to put terry cloth on tank; it soaks up condensation which then evaporates. - A more effective solution is to line the inside of the tank with foam sheets, which can be purchased from most home improvement centers. - The most permanent method is to use a device called a tempering valve, also available from most home improvement stores. This valve adds a little warm water to the tank, raising the temperature of water in tank sufficiently to prevent condensation, which also stops the toilet bowl from sweating. This solution is a little more involved, but doable.

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How A Flush Tank Works