ICP N9MP1 Service Manual

Also see for C9MPD: User's information manual User's information manual Installation instructions

ICP N9MP1 Service Manual Manual pdf 22 page image

Single Stage Multi Position FurnaceService Manual20440 08 2001 02The ìCONTINUOUSî terminal of the ST9160B control is en-ergized ONLY when there is NO OTHER CALL FOR OP-ERATION of any kind. If there is a call for HEAT, COOL, orìFAN ONî, this terminal is DE--ENERGIZED. The purposeof this terminal is to provide a means of air circulation duringìOFF CYCLESî at a different speed than either heating orcooling. The use of this terminal is operational, and therewill be no speed tap wires connected to this terminalwhen the furnace is shipped.ìCONTINUOUSî fan should not be confused with ìFAN ONîwhich is obtained by switching the fan selector switch on thethermostat sub--base to ìFAN ONî, (energizing the ìGî ter-minal) which causes the blower to run on the ìHEATINGîspeed.The ST9160B Electronic Air Cleaner terminal (EAC) ISONLY energized in conjunction with the HEATING andCOOLING speed terminals. The maximum allowable con-nected load to the HUM terminal is 0.8 (eight tenths)Amp.**The combined connected loads of the EAC and HUM termi-nals cannot exceed a total of 0.8 (eight tenths) amp.24. HONEYWELL SV9541M GAS VALVE/IGNITION CONTROLdwg 25--23--31aFigure 30 Honeywell ST9541M Ignition SystemGas Valve/Ignition ControlIgnition/SensorPilot Burner/SensorThe system consists basically of only two (2) components.The Ignition System Control and the Pilot Hardware. The op-erate on Two (2) 24 volt power circuits received from theST9160B Fan Timer/Furnace Control. One is the power sup-ply to the ignitor, the second is to activate the ignition se-quence.The Ignition System Control manages the ignition sequence,and the flow of gas to the pilot and main burners. It is in es-sence a combination Gas Valve and Ignition control.It contains sophisticated electronic components (internally)and has NO USER SERVICEABLE COMPONENTS.Should a problem be verified internally within the device, ITIS NOT REPAIRABLE, and must be replaced.The Pilot Hardware includes the pilot burner, the hot surfaceelement that lights the pilot burner, the flame rod that sensespilot flame, and the cable that attaches to the system control.The hot surface element is made of tough break resistant ce-ramic composite material. It operates on 24 Volts A.C. TheIgniter/Flame Rod assembly can be replaced independentlyfrom the pilot burner assembly.The system operation is quite simple, and forgiving (I.E. nui-sance lockouts are eliminated)25. HONEYWELL SV9541M SYSTEM OPERATIONConnecting the furnace to the line voltage supply with theblower door interlock switch closed provides 24 volts to pow-er the system. (This is accomplished by the connectionsfrom terminals [pins] #4 & #2 from the ST9160B fan timer toterminals #1 & #3 of the SV9541M gas valve.)When the thermostat calls for heat, (the combustion blowerstarts, causing the pressure switch to close completing thecircuit to the ignition system control) there will be approxi-mately a two (2) second delay, while the ignition system con-trol runs a self check.Part of the self check is to see if a flame signal is detected.If a flame signal is detected upon a call for heat (and naturallythere shouldnít be), the ignition system control will energizethe electronic fan timer output (causing the conditioned airblower to start after the fixed 60 second ìONî delay) and willkeep the valve and ignitor to circuit off.Assuming that no flame signal is detected upon the call forheat, (Normal operation), the ignition system control willpower the ignitor circuit (24 volts) causing the ignitor to heatup.If the ignitor circuit is not proven (I.E. the ignitor is missing,broken, or the connections are loose) their will be no re-sponse from the ignition system control. (Lockout)Once the ignitor circuit has been proven, and the ignitor be-gins to heat up, the pilot valve will be energized allowing gasto flow to the pilot burner.With the ignitor now hot, and gas flowing to the pilot , the pilotshould light, and the sensor should sense flame.If no flame is sensed, (I.E. no gas, pilot not lit, flame not en-veloping sensor, etc.) the ignitor will stay on, and the pilotvalve will remain open until it does sense flame, or until thecall for heat is satisfied. THE SYSTEM WILL NOT LOCKOUT under this condition.Assuming that the pilot does light, and flame is sensed, (nor-mal operation) the ignition system control will turn the ignitoroff, while energizing the main valve. This will allow the pilotto light the main burner. It will also energize the electronic fantimer output (causing the conditioned air blower to start afterthe fixed 60 second ìONî delay).