Thermo Products chx-3 75n, 100n, 125n Iv. Starting The Unit A. Sequence Of Operations

Page 42

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

IV. STARTING THE UNIT

A. SEQUENCE OF OPERATIONS

AT ANY TIME THE

CONTINUOUS SAFE OPERATION CHECK

GAS VALVE IS

IF FLAME SIMULATION CONDITION PRESENT OR ROLL-OUT SWITCH

NOT ENERGIZED

OPENS, SYSTEM ENERGIZES INDUCER FAN FOR 15 SECONDS AND

CIRCULATOR BLOWER AT HEATING SPEED UNTIL SITUATION CORRECTION

THERMOSTAT CALLS FOR

HEAT W1 OR W1 & W2,

CONTACTS CLOSE

50V51-843 CONTROL

ENERGIZED, INDUCER

ENERGIZED ON HIGH SPEED

LOW FIRE PRESSURE

SWITCHES SENSES ADEQUATE

DIFFERENTIAL PRESSURE,

CONTACTS CLOSE

PREPURGE IGNITION DELAY,

INDUCER RUNS FOR 15 SECONDS

INDUCER REDUCES

TO LOW SPEED

LOW PRESSURE SWITCH

SENSES ADEQUATE

PRESSURE DIFFERENTIAL,

CONTACTS STAY CLOSED

POWER IS APPLIED TO

THE WHITE RODGERS

SILICON NITRIDE IGNITOR.

IGNITOR WARM-UP IS

17 SECONDS

36

Image 42

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 INDEX SECTIONBEGINNING PAGE 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 K. FILTERS 1. CHX3 MODELS: HIGHBOYS Figure2. CDX3 MODELS: COUNTERFLOWS 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