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CHAPTER 5
CHAPTER 5 - INSTINCT COMBI UNITS - DOMESTIC PIPING
5.1.3 Pressure Relief Valve Discharge Piping
Pressure relief valve discharge piping must be:
• Made of material serviceable for temperatures
of 250ºF or greater.
• Directed so that hot water ows away from all
persons.
• Directed to a suitable place for disposal.
• Installed so as to allow complete draining of the
pressure relief valve and discharge line.
Pressure relief valve discharge piping must not be:
• Excessively long. Using more than 2 elbows or
15 feet of piping can reduce discharge capacity.
• Directly connected to a drain. Terminate dis-
charge piping within 6” from drain. Refer to lo-
cal codes.
• Plugged, reduced or restricted.
• Subject to freezing.
Do not install any valve between pres-
sure relief valve and tank connection or on
pressure relief valve discharge piping. Do
not plug pressure relief valve or discharge
piping. Improper placement and piping of
T&P relief valve can cause severe personal in-
jury, death or substantial property damage.
WARNING
5.2. Thermal Expansion
If a backow preventer, check valve or pressure reduc-
ing valve is piped on cold water supply piping of water
heater, install an expansion tank on cold water supply
line to prevent thermal expansion from repeatedly forc-
ing open pressure relief valve.
The pressure relief valve is not intended for con-
stant duty, such as relief of pressure due to re-
peated normal thermal expansion. Correct this
condition by installing a properly sized expan-
sion tank in the domestic water system. Refer
to expansion tank manufacturer’s installation
instructions for proper sizing.
NOTICE
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