Understanding Your Home Plumbing System
Plumbing fixtures are anything connected to the plumbing system. They include kitchen and bathroom sinks, toilets, tubs and showers, hot water tanks, and if you have one the boiler. Anything else that uses water such as dish and clothes washers and garbage disposals would also be plumbing fixtures. So you could say anything that uses or dispenses water would be a fixture.
The water supply system would be the next part of your home plumbing system. This system is made up of the pipes, faucets, fittings, pumps, valves, and tanks that supply and distribute drinkable water. Your home gets its water under pressure from either a municipal water system or sometimes from a well. Your water pressure should be in a range between 30 and 45 psi (pounds per square inch). Any pressure above 45 psi can cause your pipes to hammer or rattle. Above 65psi and it can cause your pipes to burst. You should have some type of pressure regulating valve right after the main water supply valve. If you don’t have one, they can easily be purchased and installed. Sometimes when you turn a faucet off quickly, it will cause a shock wave in the pipe and the pipe will rattle or hammer. This can be easily fix by adding an air chamber. An air chamber is a capped extension to the water pipe that is filled with air. It acts like a shock absorber to prevent the pipe from hammering.
The drainage system is made up of all the pipes that carry liquid and solid waste out of your house, and into either the sewage system or septic tank. The system works on gravity, and is made up of four components. The waste pipes, soil pipes, soil stack, and traps. Waste pipes carry water from the sinks, tubs, and add ons such as the washing machine and dishwasher. They tie into the soil stack. The soil pipes carry waste to the soil stack primarily from the toilets. Both are pitched downward so they enter the soil stack at a lower level.
The soil stack is a larger 4 inch vertical pipe that the other pipes empty into. This pipe carries the waste to the main drain which then empties into the sewer line or septic tank. Traps are installed under all the fixtures. The are usually look like a S laying on its side. They hold water in the lower elbow which acts a seal, prevent sewer gases from entering the home. Toilets have built in traps.
The venting system is tied into the drainage system. It consists of a pipe or pipes that that provide air circulation to the drainage system. This equalizes the pressure in the system to prevent water from being siphoned away from the traps. It also allow sewer gases to escape into the atmosphere.
Now it is also important to know what size and type of pipe to use. Much of this has been standardized. For example your water lines are more then likely �½ inch and if it is a newer home made from copper. Your bathroom sink has a 1 �¼ inch drain, while the kitchen sink has a 1 �½ inch drain. Your toilet should have a 3 inch pipe. Most modern drain pipes are made from PVC while the soil pipe and soil stack are normally iron. The pipe sizes are determined by a measurement called a fixture unit. A fixture unit is based on how long a cubic foot (7.48 gallons) of water takes to go down a drain. With the rate of one cubic foot a minute equaling one fixture unit. For examples a bathroom sink has a rating of one fixture unit, while a kitchen sink is rated at two fixture units. To determine the size of the drain pipes that the fixtures will flow into, it is determined that all the fixtures will be used at the same time.
