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 5 page image

Two- Stage Multi Position Furnace Service Manual3440 08 2002 02Component Locations for Four Position FurnacesFigure 1Circulating Air BlowerRating PlateGas Valve/Ignition ModuleDoor Interlock SwitchPressure SwitchesFan/Delay ControlFurnace Vent Pipe(Vent Pipe Connection throughSide Panel on Some Models)Combustion Air BlowerVent Pipe GrommetPrimary Heat ExchangerSecondary Heat Exchangerdwg 25--23--29aDiagnostic LightManual Gas ValveVent Drain Fitting3 /4²²²² OD Transition BoxDrain Hose5 /8²²²² OD Vent PipeDrain HosePlastic Transition BoxAir Intake Pipe(Dual Certified or DirectVent furnaces)Condensate TrapD C Motor Control(some models)Coils Air Baffle3. FURNACE THEORY OF OPERATIONThe high efficiencies and lower profile (compared to previousseries) of this furnace have been obtained using design tech-niques not typical of traditional furnace designs. A brief de-scription of these new design techniques and the purposethey serve follows.1. Reducing the height of the furnace while maintainingthe high efficiency of pervious models required work-ing the heat exchanger more efficiencly and yet mini-mizing the overall size.The design required to achieve these results is the ìSER-PENTINEî design, wherein the flue gasses must follow aserpent shaped passage through the heat exchanger viaconvection.This ìSerpentineî path is resistive to normal convective flow,and requires that a partial vacuum be created at the outletof the heat exchanger to maintain the flow of flue productsthrough the heat exchanger.2. The serpentine heat exchanger design does not lenditself well to the ribbon type, or slotted port type burnerfound in more traditional design furnaces for the follow-ing reasons:A.The secondary combustion airflows at right angles to theburner flame, making it likely to ìpullî the flame off a ribbonor slotted port type burner.B.The flame ìheightî of a ribbon or slotted port type burnerwould make it difficult (if not impossible) to prevent im-pingement of the flame on the heat exchanger surfaceswhole maintaining the low profile heat exchanger.For these reasons, an ìINSHOTî type burner is used in thisseries. The inshot burner (also called a ìjetî burner) fires aflame straight out its end. This burner is designed to fire intoa tube style heat exchanger, making it an ideal application inthe tube--like passages of the serpentine heat exchanger.3. In order to extract the maximum amount of heat pos-sible from the flue gasses, a secondary heat exchang-er (condenser) is connected to the outlet of the primaryheat exchanger. This condenser removes additionalheat from the flue gasses, causing their temperature todrop below dew point, thus increasing operating effi-ciency of the furnace, and the term ìCondensing Fur-naceî. This results in the forming of condensation (wa-ter) which then must be routed to a drain.4. The placement of the secondary heat exchanger at theoutlet of the primary heat exchanger creates additionalresistance to the flow of gasses.5. To overcome the resistance to convective flow of thePrimary and Secondary heat exchangers requires theuse of an Induced Draft Combustion Blower Assembly.