THERMAL PRESSURE DUE TO HOT WATER HEATERS
Starting in 1996 the District started installing dual check valves on all new meter installations to prevent backflow of water from the customer's side of the meter back in to the District's water mains for health and safety reasons. This also prevents electric water heaters from draining and burning up heating elements. Installation of the dual check valve does create a closed system on the customer side of the water meter. If you are building a new home or doing renovations be sure your plumber is aware that you have a closed system. Hot water heaters can create dangerously high-pressure due to thermal pressure.
You have several options to guard against this becoming a hazard.
1) Make sure your hot water heater is equipped with a T&P valve. (Temperature and Pressure
Valve). Never plug a leaking T&P valve. T&P valves should be vented to a drain or vented
thru the wall. T&P valves need to be periodically checked.
2) Install a ballcock with built in relief valve in the toilet tank furthermost from the hot water heater.
3) Install a hose bibb relief valve on an outside hose bibb.
4) Install an auxiliary (Bleeder) pressure relief valve for thermal expansion relief.
5) Install a potable water expansion tank on the cold-water inlet before the hot water heater.
Brochures on the above options can be obtained from the District's Office.
Discuss the above options with your plumber.
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