Thermo Products 100n, chx-3 75n, 125n operation manual Figure

Page 49

Manual background

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

Figure 23:

b.Turn the inner plastic adjustment screw clockwise to increase, or counterclockwise to decrease, the gas pressure (and gas flow) to the main burner.

c.Replace the regulator cover screw and tighten it firmly to prevent gas leakage.

d.Referring to Table 5, measure the gas pressure and to confirm it has been adjusted to within the allowable range. Repeat adjustments (a) through (c), as required.

Table 5 Design Gas Pressures for each Furnace Model Series,

Operating Mode, and Type of Fuel.

	Fuel Gas Type		Propane			Natural
	Operating Mode and	High Fire	CHX Low	CDX Low	High Fire	CHX Low	CDX Low
	Model Series		Fire	Fire		Fire	Fire
	Normal Manifold	10.0 ± 0.3	4.8 ± 0.3	5.6 ± 0.3	3.5 ± 0.3	1.8 ± 0.3	2.0 ± 0.3
	Pressure (in. W.G.)	10.0 ± 0.3	4.8 ± 0.3	5.6 ± 0.3	3.5 ± 0.3	1.8 ± 0.3	2.0 ± 0.3
	Pressure (in. W.G.)
	Maximum Gas Supply		14.0			14.0
	Pressure (in. W.G.)		14.0			14.0
	Pressure (in. W.G.)
	Minimum Gas Supply		11.0			4.5
	Pressure (in. W.G.)		11.0			4.5
	Pressure (in. W.G.)

13.Adjust the room thermostat so the burner will operate on high fire only.

14.To obtain an accurate manifold gas pressure reading, the main burner must be cycled on and off several times to stabilize the gas control valve pressure regulator diaphragm.

15.Allow the burner to operate for at least 3 minutes before taking gas pressure readings.

16.Using a pressure gauge, measure the burner manifold gas pressure.

17.If checking the input rate by measuring burner manifold pressure, proceed to step 18. If measuring the input rate by clocking the gas meter, repeat steps 9 through 11, above.

43

Image 49

Contents CHX3-75N CDX3-75N CHX3-100N CDX3-100N MODELS FOR USE WITH NATURAL GAS OR LP GAS PROPANECHX3-125N CDX3-125N 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 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 Switch Settings S7 DIP SwitchOptions 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 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 = 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