Temperature Rise

3.Calculate the number of seconds per cubic foot (sec/ ft3) of gas being delivered to the furnace. If the dial is a one cubic foot dial, divide the number of seconds recorded in step 2 by one. If the dial is a two cubic foot dial, divide the number of seconds recorded in step 2 by two.

4.Calculate the furnace input in BTUs per hour (BTU/ hr). Input equals the installation’s gas heating value multiplied by a conversion factor (hours to seconds), divided by the number of seconds per cubic foot. The measured input must not be greater than the input indicated on the unit rating plate.

EXAMPLE:

Installation’s gas heating (HTG) value: 1,000 BTU/ft3 (Obtained from gas supplier)

Installation’s seconds per cubic foot: 34 sec/ ft3

Conversion Factor (hours to seconds): 3600 sec/hr Input = (Htg. value x 3600) ÷ seconds per cubic foot Input = (1,000 BTU/ft3 x 3600 sec/hr) ÷ 34 sec/ ft3 Input = 106,000 BTU/hr

This measured input must not be greater than the input indicated on the unit rating plate.

5.Turn ON gas and relight appliances turned off in step 1. Ensure all the appliances are functioning properly and that all pilot burners are operating.

Temperature rise must be within the range specified on the unit rating plate. An incorrect temperature rise may result in condens- ing in or overheating of the heat exchanger. An airflow and tem- perature rise table is provided in the Specification Sheet applicable to your model.

Determine and adjust temperature rise as follows:

1.Operate furnace with burners firing for approximately ten minutes. Ensure all registers are open and all duct dampers are in their final (fully or partially open) position.

2.Place thermometers in the return and supply ducts as close to the furnace as possible. Thermometers must not be influenced by radiant heat by being able to “see” the heat exchanger.

SUPPLY

AIR

blower speed to increase temperature rise. Refer to Startup Procedure and Adjustment -Circulator Blower Speeds for speed changing details.

CIRCULATOR BLOWER SPEEDS

WARNING

TO PREVENT PREMATURE FAILURE OF HEAT EXCHANGER, PROPERTY DAMAGE, PERSONAL INJURY OR DEATH, DO NOT ADJUST THE LIMIT CONTROL (FACTORY-SET).

This furnace is equipped with a multi-speed circulator blower. This blower provides ease in adjusting blower speeds. The Specifica- tion Sheet applicable to your model provides an airflow table, show- ing the relationship between airflow (CFM) and external static pres- sure (E.S.P.), for the proper selection of heating and cooling speeds. The cooling blower speed is shipped set on HIGH, and the heating blower speed is set as indicated in the Specification Sheet appli- cable to your model. These blower speeds should be adjusted by the installer to match the installation requirements so as to provide the correct heating temperature rise and correct cooling CFM.

To adjust the circulator blower speed, proceed as follows:

1.Turn OFF power to the furnace.

2.Select the heating and cooling blower speeds that match the installation requirements from the airflow table in the Specification Sheet.

3.Relocate desired motor leads to the circulator blower heat and cool speed terminals on the integrated control module. (Terminals are identified as LO HEAT-H, HI HEAT-H and COOL-H (hot)). If a heating speed and the cooling blower speed are the same, a jumper wire must be used between the heat and cool terminals.

4.Connect all unused blower motor leads to the “PARK” terminals on the integrated control module. Any leads not connected to the “PARK” terminals must be taped.

5.Turn ON power to furnace.

6.Verify proper temperature rise as outlined in Section XIV, Startup Procedure and Adjustment - Temperature Rise.

*MH95, ACSH96, GCH95, GCH9

Circulator Blower Speeds

LOW	RED
MEDIUM LOW	ORANGE
MEDIUM LOW	BLUE
HIGH	BLACK
COMMON/NEUTRAL	WHITE

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