Thermo Products 100n, chx-3 75n Diagnostic Features, Power must be disconnected before servicing

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All installations and services must be performed by qualified service personnel.

memory, the LED will flash two green flashes. The control will flash the most recent error first and the oldest error last (last in first out). There will be 2 seconds between codes. Solid LED error codes will not be displayed.

DIAGNOSTIC FEATURES

The 50V51 control used on this furnace continuously monitors its operation and the operation of the system.

If the sensed failure is in the system (external to the control), the red LED will flash in the following flash- pause sequences to indicate failure status (each flash will last approximately 0.25 seconds, and each pause will last approximately 2 seconds):

Red LED Flash (DS1)

1 - flame sensed when no flame should be present 2 - pressure switch stuck closed / inducer error

3 - 1st stage pressure switch stuck open / inducer error 4 - open limit switch

5 - open rollout / aux limit

6 - pressure switch cycle lockout

7 - external lockout (retries)

8 - external lockout (recycles)

9 - grounding or reversed polarity

10 - gas flow with no call for heat

11 - limit switch open – blower failure

12 - ignitor failure

Solid - internal GV error, micro, and frequency check

3 double - 2nd stage pressure switch stuck open / inducer error

The LED will also flash once at power-up.

Amber LED Flash (DS1)

1 – normal call for first stage heat

2 – normal call for second stage heat

3 – W2 present with no W1

4 – Y present with no G call Rapid – low flame sense current

Green LED indicator (DS2) is present to obtain an estimate of the air flow rate (in CFM) produced by the house air blower. This LED cycles regularly by providing a constant light, followed by a sequence of flashes. Each flash can be translated to programmed CFM by using the following:

1 flash per 100(programmed) CFM

: Power must be disconnected before servicing.

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Contents INSTALLATION AND OPERATION MANUAL MODELS FOR USE WITH NATURAL GAS OR LP GAS PROPANECHX3-75N CDX3-75N CHX3-100N CDX3-100N CHX3-125N CDX3-125NI. SAFETY INFORMATION This and the previous page contain reproductions of the various warning and instruction labels placed on the Thermo Pride Two Stage Condensing Gas Furnaces. Please read and comply with the contents of these labels 1.A windows be opened The CHX3/CDX3 furnace models are sealed combustion design, which does not require an air shutter adjustment air shutters are not used for proper flame characteristics. Burner box access cover must always be secured with all screws in place and tightened before operating furnace SECTION INDEXBEGINNING PAGE II. FURNACE SPECIFICATIONS CDX3 SERIES INSTALLATION PARTS PACKAGES – CHX3-75 INSTALLATION PARTS PACKAGES – CDX3-75 Grounding instructions III. GENERAL INSTALLATION B1. CDX3 HORIZONTAL APPLICATION B. FURNACE LOCATIONFigure PVC Pipe Designation Maximum Quantity of Elbows Outside Combustion Air Intake RH view E.Direct Venting Through a Sidewallc.The vent terminal shall not be located •near soffit vents, crawl space vents, or other areas where condensate or water vapor could create a nuisance, hazard, or cause property damage, and Page E1. Single-PipeSidewall Venting Option 5.Optional Direct Vent Terminations Install these optional kits according to the instructions provided with each kit. The location and clearance requirements are identical to those of the standard vent terminations described in this manual 1.Figures 6B, 7, and 8 follow depicting typical exhaust vent and air intake connections for the furnace model series CHX3 and the CDX3, respectively, as well as a list of required parts to correctly install each system Applications Applications leading away from the furnace must be composed of 3-inchdiameter PVC pipe and pipe fittings only. Refer to item E in Figure 3. Connecting The Combustion Air Intake Piping Figure 14. TRAP ASSEMBLY MOUNTED ON CHX3 I.CONDENSATE DRAIN LINE AND TRAP ASSEMBLYFigure 15. TRAP ASSEMBLY MOUNTED ON CDX3 2.Determine on which side of furnace the condensate disposal line is to be run NOTICE: On CHX3/CDX3’s this must be the same side as the flue outlet or bottom of unit. Attach the condensate trap to the furnace casing using the #8x3/4” sheet metal screws provided in the parts package. Pilot holes are provided on both sides of the casing for mounting J. GENERAL GAS PIPING J1. REQUIREMENTS AND SIZING OF DUCT WORK Figure 18A TABLE 2A Figure K. FILTERS 1. CHX3 MODELS: HIGHBOYS2. CDX3 MODELS: COUNTERFLOWS Figure L. WIRING Table 4A Time S7 DIP SwitchSwitch Settings Options2-StageBlower Settings from factory Table 4C IV. STARTING THE UNIT A. SEQUENCE OF OPERATIONS FLAME MUST BE DETECTED IF THERMOSTAT W2 CONTACTS ARE CLOSED OTHERWISE OPERATING INSTRUCTIONS B. INITIAL START UPB.Gas flowrate by clocking gas meter C. Measuring And Adjusting Heat Input RateObserve the following precautions when measuring A.Burner manifold pressure with a pressure gaugeNOTICE: A U-tubemanometer, measuring pressure in inches of water column, is recommended for all gas pressure measurements. However, an aneroid pressure gauge, in good working condition, capable of reading pressure changes of 0.05 in. W.G., or less, that was recently calibrated within the last year, is a satisfactory alternate. These two 2 devices will be considered as equivalent and interchangeable. Either device is referred to below as a “pressure gauge” Heat input rate in BTUH = Figure Checking The Burner Flame 21.Go to Checkout Procedure belowCheckout Procedure TABLE 6 - CONVERTING GAS FLOW RATE V. INSTALLERS INSTRUCTIONS TO USER D. FURNACE CHECKOUT PROCEDUREFigure VI. TROUBLESHOOTING Power must be disconnected before servicing DIAGNOSTIC FEATURESTROUBLESHOOTING GUIDE IS INDUCER RUNNING ON LOW SPEED? YES DOES THE HOT DO BURNERS STAY LIT PAST PROOF OF FLAME CHECK? REPLACE THE 50V51-843CONTROL CHECK FOR 24 VOLTS Appendix –AReplacement Parts List Page Page Page Appendix – B Wiring Diagrams