Thermo Products CDX3-125N, CDX3-75N, CHX3-75N, CHX3-125N C. Measuring And Adjusting Heat Input Rate

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C. Measuring And Adjusting Heat Input Rate

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

C. Measuring And Adjusting Heat Input Rate

DO NOT exceed input rating stamped on furnace nameplate or manufacturer's recommended burner manifold pressure for orifice size used.

Observe the following precautions when measuring:

A.Burner manifold pressure with a pressure gauge.

1.Close the gas valve (turn the gas control knob to the OFF position) BEFORE removing the:

a.burner manifold pressure tap plug to connect the manometer (or calibrated pressure gauge)

b.manometer, or gauge, and replacing the pressure tap plug.

2.Shut off the gas supply at the appliance service (manual gas shutoff) valve (or for LP gases, shut off the gas at the storage tank service valve) BEFORE removing the:

a.gas valve inlet pressure tap plug

b.manometer, or gauge and replacing the inlet pressure tap plug.

3.Perform a gas leakage test at the gas valve inlet and burner manifold pressure tap plugs.

B.Gas flowrate by clocking gas meter.

1.To determine the amount of flow, through the gas meter, due to the operation of the furnace.

a.Turn off all other appliances and extinguish their pilot flames, if equipped, or

b.Deduct the gas consumption of all other operating appliances from the total meter reading.

2.Convert the gas flowrate to the heat input rate (in BTUH) as described in step 10 (in the following section) and compare the value to the heat input rating on the furnace nameplate.

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Contents MODELS OR LP GAS PROPANE CDX3-75N CDX3-100N CDX3-125NTWO STAGE CONDENSING GAS FURNACE I. 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 INDEX SECTIONBEGINNING PAGE II. FURNACE SPECIFICATIONS CHX3 SERIES CDX3 SERIES INSTALLATION PARTS PACKAGES - CHX3-75 INSTALLATION PARTS PACKAGES - CDX3-75 Grounding instructions III. GENERAL INSTALLATION B1. CDX3 HORIZONTAL APPLICATION B. FURNACE LOCATIONPage 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 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 Page Applications Figure 9 Typical Internal Vent Piping Arrangement for theFurnace Model Series CHX3 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 2. CDX3 MODELS COUNTERFLOWS K. FILTERS 1. CHX3 MODELS HIGHBOYSPage L. WIRING Table 4A Switch Settings S7 DIP SwitchOptions Time2-StageBlower Settings from factory Table 4C IV. STARTING THE UNIT A. SEQUENCE OF OPERATIONS IF NOT IF THERMOSTAT W2 CONTACTS ARE CLOSED OTHERWISE OPERATING INSTRUCTIONS B. INITIAL START UPObserve the following precautions when measuring C. Measuring And Adjusting Heat Input RateA.Burner manifold pressure with a pressure gauge 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 = Page 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 DOESBURNERSHUT OFF Appendix -AReplacement Parts List Page Page Page Appendix - B Wiring Diagrams