GSW Electric Water Heate Pressure Build-Upthermal Expansion, Spacesaver Models Side Outlet Only

PRESSURE BUILD-UP (THERMAL EXPANSION)

During the heating cycle of the water heater, the water expands creating a pressure build-up in the plumbing system. If the pressure exceeds 150 PSI, water will come out of the valve. This is a normal safety function of the T&P valve. The water supply meter may have a check valve or back flow preventer inside. This can increase the possibility of pressure build-up. Causes of discharge can be thermal expansion, excess system pressure, too high a temperature setting on the thermostat or something in the water heater causing excess temperatures in the heater.

Thermal Expansion: When water is heated it expands. For example, in a 40-gallon water heater, water being heated to its thermostat setting will end up expanding by approximately 1/2 gallon. This extra volume created by the expansion has to go somewhere or pressure will dramatically increase, such as when water is heated in a closed system. A good indication of thermal expansion is when the T&P valve releases about one cup of water for every 10 gallons of heater capacity with each heating cycle. The T&P valve is functioning properly when it relieves pressure caused by thermal expansion, but frequent relief can result in a build up of natural mineral deposits on the valve seat, rendering the valve inoperative. Should this happen, the T&P valve needs to be replaced.

To prevent this ‘T & P VALVE’ from discharging hot water, the loss of energy and reduce the possible build-up of lime in the ‘T & P VALVE’ there are two (2) recommendations:

OPTION 1: Install a 125 PSI Pressure Relief (only) valve in the cold water supply line. Make sure that the discharge of this valve is directed to a drain to prevent water damage and it is protected from freezing,

OR

OPTION 2: Install an expansion tank on the cold water supply line. For every 50 U.S. gallons of stored water, the expansion tank must have a minimum capacity of 1.5 U.S. gallons.

Temperature Relief: The T&P valve will discharge varying amounts of water, but typically more than you would experience from thermal expansion. Check the temperature in relation to the setting on the thermostat dial. A malfunctioning thermostat could cause the water to get too hot.

Alternate location of pressure relief valve	Location of pressure relief and \ or expansion tank if a check valve or
OPTION 2
	pressure reducing valve is in the cold water supply to the house.

Use option 1 or 2 as convenient. If a pressure relief valve is used (OPTION 1) select one with a setting 25 psi below the relief valve rating used on the heater.

OPTION 1

1.Cold water inlet

2.Hot water outlet

3.Anode(s)

4.Temperature and pressure relief valve*

5.Thermostat

6.Element

7.Access door – not illustrated

8. Floor drain

9.Drain valve

10.Water supply to meter

11.Water supply to home

12.Water meter with backflow preventer

13.Overflow

14.Pressure relief valve

15.Expansion tank

*Items to be supplied by installer

SPACESAVER™ MODELS

(SIDE OUTLET) ONLY

NOTE TO INSTALLERS:

A bent tube (as shown) is installed for the hot water outlet on side outlet water heaters to ensure a maximum of hot water supply.

This fitting must be aligned properly.

The ‘line’ on the fitting must be oriented pointing up. When in correct position, the hot water is drawn from the highest point in the tank.

Refer to pressure relief \ expansion tank schematic above.

Tee fitting and drain valve

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