Toilet parts

[fred1949]

In my toilet tank there is a cylinder surrounding the flapper. What does that do & could you recomend replacement parts for a toilet tank. There are several replacement options that range from the old standard to a little thing that looks like a clam shell. I now have the verticle valve with the float arm. It is a 1 gal. per flush.

Thank you,
Fred

[LazyPup]

In order to explain that tube we must first examine the physics of how a toilet flushes.



Notice that when the toilet is in the at rest position the water level in the bowl is just up to the base of the trap.



When the flush begins it is vitally important that the water level in the bowl must rise rapidly to quickly fill the trap, displacing the air in the top of the trap and starting a syphon effect.



Once the syphon effect begins the atmospheric air pressure pushing down on the top of the water in the bowl will continue pushing the water through the trap.



As soon as the atmospheric air can enter the trap it will break the syphon action and the flush is complete. A small amount of the water that was entering the trap will now fall back into the bowl. During the tank fill cycle the small "Trap Primer" line from the fill valve will feed water down through the standpipe and into the bowl to insure a proper water level in the bowl and trap.

Years ago toilets were designed to discharge 4.5 to 5 gallons per flush. In the early 80's the government began setting water conservation mandates that required the flush volume to be reduced to 3.5gpf which was again reduced to the current 1.6 gal/flush.

As you can see from the illustrations the flushing action is done solely by the gravity flow of water from the tank to the bowl. The static head pressure required to push the water into the bowl is determined by the depth of the water in the tank. If we were to attempt to conserve water by lowering the tank level we no longer have sufficient static head pressure to push the water into the bowl fast enough to flood the trap and begin the syphon.

One of the early methods that was tried was to install a riser tube around the flush valve such as you have. In that manner they could still use the same size of tanks and keep the water level at the necessary height. They could then still use the 3.5 or 5 GPF tanks but the addition of a standpipe riser around the flush valve causes the tank to trap about 2 gallon in the bottom of the tank that does not discharge, thereby achieving the required water conservation.

The next improvement was to add another internal water fill port down the front and to the base of the bowl. As the water flows from the tank to the bowl a rapid stream of water is dispersed from the base of the bowl in the direction of the trap. This causes the trap to fill quicker and effects an assisted flush. (Actually that method had been used for years in commercial toilets that have Flushometer valves).

Next they settled on the idea keeping the heigh of the tank the same, but reducing the water volume by making the tanks narrower and thinner. This still afforded the necessary height to acheive the necessary static head pressure but it significantly reduced the volume per flush.

The problem here was that often the velocity of flow was not sufficient to overcome the additional friction of solid waste in the water flow. This explains why many of the earlier model 1.6 GPF toilets tend to clog more often and are not well received by the consumer.

Finally they came up with the idea of lowering the height of the top of the trap. In so doing it greatly diminishes the amount of water required to flood the trap and start the syphon, however, this also explains why many new toilets seem to have a much lower water level in the bowl than what the older toilets had.

Now in regards to what type of flush valves to use when repairing a toilet. In those instances when I can use a universal replacement type fill valve or flush valve I personally prefer the "Fluidmaster" products. I dont know that they are any better than the others but I have been using fluidmaster products almost exclusively since they first came on the market in the early 80's and I have come to trust that brand.

Quite often one piece toilet and some tank & Bowl combinations have pressure assisted flushing mechanism. In those instances the fill valve & flush valves must be replaced with exact replacement parts but for the most part the conventional Tank & Bowl style toilets have standard Ballcock filling mechanism. If you have a conventional ballcock fill valve you can easily replace it with a "Fluidmaster" type universal replacement fill valve.

If you have a conventional flapper style flush valve there really should be no necessity to ever change anything but the flapper. The remaining portion of the flush valve is simply an open port from the tank to the bowl with no working parts other than the flapper ball which serves as a trap door over the opening. Sometimes as the toilet ages the top surface of the flush valve becomes rough from mineral scale buildup, which then prevents the flapper from seating properly. The end effect is a small amount of water seeping under the flapper into the bowl, which causes the fill valve to repeatedly open to make up the loss. In most cases you can simply take a piece of medium emery cloth and burnish the top surface of the flush valve seat where the flapper rests to insure it is smoooth.

If you examine the underside of a flapper you will note that it has a rubber dome like a blister with a hole in the center. In the at rest position the water chamber under the flapper has air in it. When the flapper is raised by the flush handle chain a small amount of air is trapped in that little dome forming a bubble that keeps the flapper elevated until the water is completely discharged from the tank.

While all flappers may intitially appear to the the same, in recent years with the advent of low volume flush toilets the diameter of the opening on the flapper ball has been reduced to prolong the open time to match the volume of the tanks. When selecting a replacement flapper it is important to be sure you get one rated for the Gallon per flush rate of your tank. If you happen to get the old style flapper and install it on a 1.6 gpf tank it will result in the flapper closing prematurely and causes an incomplete flush.

Fluidmaster now makes a universal replacement flapper that has a rigid plastic frame to hold the rubber flapper ball and the ball has an eccentric hole in the bubble chamber. With this style of flapper you can rotate the rubber ball to adjust the flapper from 1.6 to 5 gpf to match your tank.