MG & SG Series Boilers – Installation and Service Manual
12
2.13 PRESSURE RELIEF VALVE
A pressure relief valve is supplied as standard equipment. The pressure relief valve is extra protection
against damage that could be caused by malfunctioning controls or excessive water pressure. If a
pressure relief valve is not used, the warranty is void.
The pressure relief valve should be installed on the boiler outlet with its spindle vertical. The connection
between the boiler and the relief valve must have at least the area of the valve inlet.
A discharge pipe should be used. The discharge pipe outlet should be positioned over a suitable drain
and so arranged that there will be no danger of being scalded. The discharge pipe must pitch down from
the valve and should be no smaller than the outlet of the valve. The end of the discharge pipe should not
be concealed or threaded and should be protected from freezing. Extensive runs, traps or bends could
reduce the capacity of the pressure relief valve.
No valve of any type should be installed between the pressure relief valve and unit or in the discharge
pipe. The pressure relief valve is a code requirement. Field installation of the relief valve must be
consistent with the ANSI/ASME Boiler and Pressure Vessel Code, Section IV.
Avoid contact with the hot water discharged to prevent personal injury.
2.14 ELECTRICAL WIRING
All electrical wiring must conform with the requirements in Section 2.2.
Run a separate circuit from the electrical service panel through a fused disconnect switch to the boiler.
This boiler must be electrically bonded to ground in accordance with the requirements of the authority
having jurisdiction or, in the absence of such requirements, with the National Electrical Code, ANSI/NFPA
70 (current edition) and and/or the Canadian Electrical Code, CSA C22.1 Part 1 (current edition). Field
wiring shall conform to Section 2.2 and to the temperature limitations of Type T [63°F (35°C) rise] or
better.
Make connections as shown in the wiring diagrams provided. For details of electrical wiring for different
pilots and controls, refer to wiring diagrams included in this manual.
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