Lennox International Inc GWB9-075IH-2 Casting Temperature Safety Switch, Drain Valve

CONTROLS AND ACCESSORIES

Casting Temperature Safety Switch

In event of lack of or loss of water in boiler, Casting Temperature Safety Switch (300 °F setpoint) installed on top of the aluminum boiler section shuts off boiler by shutting off power to Integrated Boiler Control (IBC). This fault requires manual reset of casting temperature safety switch to restart the boiler. Verify that boiler is properly filled with water before resetting this switch.

Never run cold water into a hot empty boiler.

Drain Valve

Manual drain valve provides means of draining water in heating system, including boiler and hot water supply and return piping systems installed above drain valve. This drain valve is installed in ¾” tapping at bottom of front boiler section. Any piping installed below elevation of this drain valve will require additional drain valves to be installed at low points in piping systems in order to drain entire system.

Differential Pressure Air Proving Switch/Blocked Vent Safety Shutoff

Differential pressure switch monitors air flow by sensing differential pressure measured in inches of water (” w.c.). Pressure switch contacts close when draft inducer is running. Closed switch indicates there is adequate air flow for combustion. Pressure switch shuts off main burner if differential pressure is inadequate due to blocked vent pipe, blocked air intake, blocked boiler sections, or blocked draft inducer. If pressure switch contacts fail to close control will display Error Code 29.

Draft Inducer

Draft inducer (blower) provides means for pulling combustion air into and through the mixer, burner, flue ways of cast aluminum boiler sections and flue adapter before being discharged through vent piping to outdoors. See applicable sections for proper sizing and installation of combustion air and vent piping in this manual.

Circulator Pump

Every forced hot water system requires at least one circulating pump.

Circulating pump imparts the necessary energy to move water through closed loop supply and return piping systems, terminal heating equipment (i.e. finned tube radiators, etc.) and back through boiler for reheating.

To provide required hot water flow rates, circulator pump must be properly sized to overcome frictional losses (usually measured in feet of water, also referred to as “pump head loss”) of supply and return piping systems and boiler.

The circulator pump is furnished for single zone or zone valve controlled heating system and should be located on downstream (i.e., pumping away) side of expansion tank. For pump controlled system (where there is a circulator for each zone) circulator provided with boiler can work for one zone. For more details on piping and circulators, see “Near Boiler Piping” on page 11.

A.S.M.E. Rated Pressure Relief Valve

Each boiler must have a properly sized and installed American Society of Mechanical Engineers rated pressure relief valve. Water expands as it is heated by burner/ boiler sections. If there is no place for water to expand its volume, (i.e. a properly sized and properly functioning expansion tank) pressure on inside of boiler and heating system will increase. Furnished relief valve automatically opens at 30 psig pressure to relieve strain on boiler and heating system from increasing pressure. Pressure relief valve discharge must be piped with piping same size as valve discharge opening to open drain, tub or sink, or other suitable drainage point not subject to freezing, in accordance with A.S.M.E. specifications and requirements of local jurisdiction.

External Condensate Pump (Optional)

For installations where there is no floor drain or other appropriate drainage receptacle available to receive condensate from the boiler, an external float activated condensate pump with integral sump is required. This unit can be installed to pump the condensate to a remote tie in point to a sanitary sewer system. For this application, the boiler must be installed so that proper pitch of piping to the external condensate reservoir (sump) can be accomplished. Use wood frame or blocks to raise boiler as required for proper installation.

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