ICP 9MPT Service Manual

Also see for 9MPT Series: User's information manual User's information manual Installation insrtuctions Installation insrtuctions

ICP 9MPT Service Manual Manual pdf 10 page image

Two- Stage Multi Position FurnaceService Manual8440 08 2002 0210. CHECKING TEMPERATURE RISEChecking Temperature RiseFigure 8Thermometer:Return Air Temp.Thermometer;Supply Air Temp.SupplyAir FlowAir FlowReturnThe furnace is designed to operate within a certain specifiedrange of temperature rise.Operating the furnace outside the specified range may resultin lower efficiency and/or comfort levels, as well as prema-ture combustion component failures.Simply stated, the temperature rise through the furnace isthe difference in temperature between the return air, and thesupply air.NOTE: BEFORE CHECKING TEMPERATURE RISE BECERTAIN THAT MANIFOLD PRESSURE IS PROPERLYADJUSTED.ALLOWABLE TEMPERATURE RISE FOR2- STAGE MODELSModel Fire Range50 Mbtu HI 35°F -- 65°F50 Mbtu LOW 25°F -- 55°F75 Mbtu 100 Mbtu & 125 Mbtu HI 40°F -- 70°F75 Mbtu, 100 Mbtu & 125 Mbtu LOW 30°F -- 60°FAlways check current ìTechnical Support ManualîALLOWABLE TEMPERATURE RISE FORVARIABLE SPEED MODELSModel Fire Range50 Mbtu HI 35°F -- 65°F50 Mbtu LOW 35°F -- 65°F75 Mbtu 100 Mbtu & 125 Mbtu HI 40°F -- 70°F75 Mbtu, 100 Mbtu & 125 Mbtu LOW 40°F -- 70°FAlways check current ìTechnical Support ManualîOperate the furnace for 15 minutes before taking tempera-ture readings. Subtract the return air temperature from thesupply air temperature. The result is the temperature rise.Compare with the allowable rise listed for the model (size)you are checking.Temperature Rise can be checked by placing a thermometerin the return air duct within 6¢ of furnace. Place a second ther-mometer in the supply duct at lease two (2) ft. away from thefurnace. (This will prevent any false readings caused by radi-ation from the furnace heat exchanger) Make sure that theFILTER IS CLEAN and that ALL REGISTERS AND/ORDAMPERS ARE OPEN.If the rise is not within the specified range, it will be necessaryto change the heating blower speed. If the rise is too high,it will be necessary to increase the blower speed. If therise is too low, it will be necessary to reduce the blowerspeed.Example:Supply Temp. 170°Return Temp. 70°Temperature Rise 100° = Too HighSolution: Increase Blower Speed11. ROOM THERMOSTATSRoom thermostats are available from several differentmanufactures in a wide variety of styles. They range from thevery simple and inexpensive Bi--metallic type to the complex.They are simply a switch (or series of switches) designed toturn equipment (or components) ìONî or ìOFFî at the de-sired conditions.An improperly operating, or poorly located room thermostatcan be the source of perceived equipment problems. A care-ful check of the thermostat and wiring must be made then toinsure that it is not the source of problems.