Thermo Products 125n, chx-3 75n, 100n Go to Checkout Procedure below, Checking The Burner Flame

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

18.If the gas pressure is not within the specified high fire manifold pressure range (refer to Table 5), repeat steps 12(a) through 12(d), above, adjusting the high fire gas pressure regulator.

If the manifold pressure remains low and it cannot be adjusted into the proper range, the supply pressure may be too low. Follow these steps.

a.Turn off the gas at the manual gas shutoff valve.

b.Remove the automatic gas control valve inlet pressure tap and attach another pressure gauge to the inlet tap.

c.Turn on the gas and repeat steps 14 and 15, above.

d.Adjust the upstream (inlet) gas pressure to 14.0 in. W.G., or as close as possible.

e.Using a pressure gauge, measure and adjust the burner manifold gas pressure.

If it is still not possible increase the manifold gas pressure to within the required range, there is too little gas supply to operate the furnace at full (high fire) input rate under present conditions. If necessary, consult your gas supplier or qualified heating contractor for recommendations to alleviate the problem.

19.Turn off the gas at the manual gas shutoff valve (turn handle to the OFF position).

20.Remove all pressure gauges and replace all pressure tap plugs.

21.Go to Checkout Procedure below.

Adjusting Burner Input For Altitudes Above 2000 Feet

Ratings of gas utilization equipment are based on sea level operation and shall not be changed for operation at elevations up to 2,000 feet (600 m.). For operation at elevations above 2,000 feet (600 m), equipment ratings shall be reduced at the rate of 4 percent for each 1,000 feet (300 m) above sea level.

For additional information, refer to the latest edition of the National Fuel Gas Code.

Checking The Burner Flame

cCAUTION: The furnace model series CDX3 and CHX3 are sealed combustion designs that do not require an air shutter adjustment (air shutters are not used) for proper flame characteristics. The burner box access cover must always be secured with all screws in place and tightened before operating furnace.

Once the input rate has been confirmed correct for a specific application, the burner flames should be checked for proper adjustment.

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Contents CHX3-125N CDX3-125N MODELS FOR USE WITH NATURAL GAS OR LP GAS PROPANECHX3-75N CDX3-75N CHX3-100N CDX3-100N INSTALLATION AND OPERATION MANUALI. 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 BEGINNING PAGE INDEXSECTION II. FURNACE SPECIFICATIONS CDX3 SERIES INSTALLATION PARTS PACKAGES – CHX3-75 INSTALLATION PARTS PACKAGES – CDX3-75 Grounding instructions III. GENERAL INSTALLATION B. FURNACE LOCATION B1. CDX3 HORIZONTAL APPLICATIONFigure PVC Pipe Designation Maximum Quantity of Elbows E.Direct Venting Through a Sidewall Outside Combustion Air Intake RH viewc.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 I.CONDENSATE DRAIN LINE AND TRAP ASSEMBLY Figure 14. TRAP ASSEMBLY MOUNTED ON CHX3Figure 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 2. CDX3 MODELS: COUNTERFLOWS K. FILTERS 1. CHX3 MODELS: HIGHBOYSFigure Figure L. WIRING Table 4A Options S7 DIP SwitchSwitch Settings Time2-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 B. INITIAL START UP OPERATING INSTRUCTIONSA.Burner manifold pressure with a pressure gauge C. Measuring And Adjusting Heat Input RateObserve the following precautions when measuring B.Gas flowrate by clocking gas meterNOTICE: 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 21.Go to Checkout Procedure below Checking The Burner FlameCheckout Procedure TABLE 6 - CONVERTING GAS FLOW RATE D. FURNACE CHECKOUT PROCEDURE V. INSTALLERS INSTRUCTIONS TO USERFigure VI. TROUBLESHOOTING DIAGNOSTIC FEATURES Power must be disconnected before servicingTROUBLESHOOTING 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