Greenville, SC area......
If you think you have high water pressure, or you find there is no thermal expansion tank on the cold water line to your water heater, give me a call........here's why.....
Excessive water pressure and Thermal expansion, if not compensated for in the system design, will lead to the early failure of components. These failures are usually not covered by the manufacturers warranty, so it is extremely important that everyone be aware of the causes and solutions to thermal expansion and high pressure in a closed water heating system.
Causes of excessive pressure and thermal expansion
All homes that are connected to the public water supply in this area, are required to have check valves near the meter to help keep the water supply safe. This ensures that no water from a home that has an illegal cross connection with a well, or the lack of back-flow preventer's can enter the town water supply. Unfortunately, this turns your home into a "closed system" where water pressure has no place to be relieved since it can no longer be vented back to the public water supply.
1. One problem that can cause over-pressure of the system is the Pressure Reducing Valve (PRV). This valve is installed the incoming water line of the home. The PRV's job is to keep the incoming water pressure within code limits. Code specifies the water pressure in a residential plumbing system should never be at, or above 80 pounds per square inch.
IF THE PRESSURE RISES TO 80PSI OR ABOVE A NEW PRESSURE REGULATOR NEEDS TO BE INSTALLED.
2. The other problem is thermal expansion. As water is heated in the tank, it expands and pressure is built up like it is in a pressure cooker. The extra pressure has no place to be relieved and its the tank, piping, and fixtures that take the punishment, because the required check valve by the meter doesn't allow water back to the public water system.
In severe cases the temperature and pressure valve (T&P) will seep water. This can cause mineral build up in the line, causing a blockage which could make the T&P ineffective and could lead to a tank rupture. Water heater manufacturers require means to compensate for thermal expansion, or they may not honor their warranty.
THE T&P VALVE ON THE WATER HEATER IS NOT THERE TO ACT AS A CONTROL VALVE!
IF IT SEEPS WATER IT IS AN INDICATION OF A PROBLEM IN THE SYSTEM!
1. The pressure must be maintained within the code limits. This is done by checking the PSI on the house water system. If the pressure is 80 or more a new PRV needs to be installed. This keeps the baseline pressure at reasonable levels.
2. An expansion tank needs to be fitted to the cold water inlet of the water heater to eliminate thermal expansion, as the water heater goes through its normal heating cycles.
With this setup your plumbing supply system will always be working under ideal pressure conditions. The heater, pipes, and fixtures connected to it will give you the best possible life expectancy, maintain warranties, and require minimum maintenance.