Gas Fired Make-up Air Unit Packaged Indoor Arrangements​ - High Limit and/or Safety Limit Maintenance

WARNING: Hazardous Voltage and Gas! Failure to turn off gas or disconnect power before servicing could result in an explosion or electrocution which could result in death or serious injury. Turn off the gas supply and disconnect all electric power, including remote disconnects, before servicing the unit. Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized.

To service or replace high limit and/or safety limit:

• Turnoff the manual gas valve and electrical power to the unit.

To service the High Limit:

• Remove the Mounting Cover located on the access side of the unit toward the rear (Air Inlet) of the furnace section. Remove the mounting plate from the side panel of the heat exchanger. The mounting plate is part of the High Limit; making note of wire locations for reconnecting.

• Remove all electrical connections from the High Limit; making note of wire locations for reconnecting.

• Reassemble the High Limit by replacing all parts in order; making sure the High Limit is making proper surface contact when installed.

To service the Safety Limit:

• Remove Mounting Cover located on the access side of the unit toward the front (Air Outlet) of the furnace section.

• Remove all electrical connections from the Safety Limit; making note of wire locations for reconnecting.

• Reassemble the Safety Limit by replacing all parts in order; making sure the Safety Limit is making proper surface contact with the side of the heat exchanger.

• Complete appropriate start-up procedure as given in the Start-Up section of this manual.

• Check Burner Adjustment.

• Check gas control valves and pipe connection for leaks.

• Check operation of auto gas valve.

• Check operation of safety devices.

• Inspect and service blower section of system.