Closed System/Thermal Expansion
As water is heated, it expands (thermal expansion). In a closed system, the volume of water will grow. As the volume of water grows, there will be a corresponding increase in water pressure due to thermal expansion. Thermal expansion can cause premature tank failure (leakage). This type of failure is not covered under the limited warranty. Thermal expansion can also cause intermittent temperature- pressure relief valve operation: water discharged from the valve due to excessive pressure build up. The
A properly sized thermal expansion tank should be installed on all closed systems to control the harmful effects of thermal expansion. Thermal expansion tanks are available from Sears stores and through the Sears Service Centers. Contact the local plumbing inspector, water supplier and/or the Sears Service Center for assistance in controlling these situations. (For additional information, see the Troubleshooting Guide later in this manual.)
Temperature and Pressure Relief Valve
Explosion Harzard
•
• Properly sized temperature- pressure relief valve must be installed in opening provided.
• Can result in overheating and excessive tank pressure.
• Can cause serious injury or death.
For protection against excessive pressures and temperatures, a temperature and pressure relief valve must be installed in the opening marked “T & P RELIEF VALVE.” (See Figure 24). This valve must be design certified by a nationally recognized testing laboratory that maintains periodic inspection of the production of listed equipment or materials as meeting the requirements for Relief Valves for Hot Water Supply Systems, ANSI Z21.22. The function of the temperature and pressure relief valve is to discharge water in large quantities in the event of excessive temperature or pressure developing in the water heater. The valve’s relief pressure must not exceed the working pressure of the water heater as stated on the rating plate.
IMPORTANT: Only a new temperature and pressure relief valve should be used with your water heater. Do not use an old or existing valve as it may be damaged or not adequate for the working pressure of the new water heater. Do not place any valve between the relief valve and the tank.
The Temperature & Pressure Relief Valve:
•Must not be in contact with any electrical part.
•Must be connected to an adequate discharge line.
•Must not be rated higher than the working pressure shown on the rating plate of the water heater.
The Discharge Line:
•Must not be smaller than the pipe size of the relief valve or have any reducing coupling installed in the discharge line.
•Must not be capped, blocked, plugged or contain any valve between the relief valve and the end of the discharge line.
•Must terminate a maximum of six inches above a floor drain or external to the building.
•Must be capable of withstanding 250°F (121°C) without distortion.
•Must be installed to allow complete drainage of both the valve and discharge line.
T&P Relief Valve and Pipe Insulation
1.Locate the T&P Relief Valve on the water heater.
2.Locate the slit running the length of the insulation.
3Spread this slit open and slip it up under the T&P Relief Valve. See Figure 25. Apply gentle pressure to the insulation to ensure it is fully seated on the T&P Relief Valve. Once sealed secure the insulation with a section of tape. IMPORTANT: The insulation or tape should not block or cover the T&P Relief Valve drain opening. Also the insulation or tape should not block or hinder access to the T&P Relief Valve manual relief lever.
4. | Next locate the hot water (outlet) & cold water (inlet) pipes to |
| the water heater. |
5. | Select one of the sections of pipe insulation and locate the slit |
| that runs the length of the insulation. |
6. | Spread the slit open at the base of the insulation and slip it |
| over the cold water (inlet) pipe. Apply gentle pressure along |
| the length of the insulation to ensure it is fully seated around |
| the cold water pipe. Also ensure that the base of insulation is |
| flush with the water heater. Once seated, secure the insulation |
1” MINIMUM
METAL DRAIN PAN 
DRAIN |
TEMPERATURE AND PRESSURE (T&P) RELIEF VALVE (OPTIONAL TOP T&P RELIEF VALVE NOT SHOWN)
DISCHARGE PIPE
(DO NOT CAP OR PLUG)
DRAIN LINE 3/4” ID MINIMUM
6” MAXIMUM AIR GAP
with a section of tape. |
7. Repeat steps 5 through 6 for the hot water (outlet) pipe. |
T&P RELIEF VALVE INSULATION
MANUAL RELIEF LEVER
T&P RELIEF VALVE |
T&P RELIEF VALVE
DRAIN LINE
FIGURE 24.
FIGURE 25.
21
