UNVENTED (VENT-FREE) GAS LOG HEATER OWNER’S OPERATION AND INSTALLATION MANUAL 24" THERMOSTAT MODELS CDR3924NT AND CDR3924PT WARNING: If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life. — Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance. — WHAT TO DO IF YOU SMELL GAS • Do not try to light any appliance.
WARNING: Improper installation, adjustment, alteration, service, or maintenance can cause injury or property damage. Refer to this manual for correct installation and operational procedures. For assistance or additional information consult a qualified installer, service agency, or the gas supplier. WARNING: This appliance is for installation only in a solid-fuel burning masonry or UL127 factory-built fireplace, or in an listed ventless firebox enclosure.
SAFETY INFORMATION WARNING: This product contains and/or generates chemicals known to the State of California to cause cancer or birth defects, or other reproductive harm. IMPORTANT: Read this owner’s manual carefully and completely before trying to assemble, operate, or service this heater. Improper use of this heater can cause property damage and serious injury or death from burns, fire, explosion, electrical shock, and carbon monoxide poisoning.
SAFETY INFORMATION Continued 1. This appliance is only for use with the type of gas indicated on the rating plate. This appliance is not convertible for use with other gases. 2. Do not place propane/LP supply tank(s) inside any structure. Locate propane/LP supply tank(s) outdoors. 3. If you smell gas • shut off gas supply • do not try to light any appliance • do not touch any electrical switch; do not use any phone in your building • immediately call your gas supplier from a neighborʼs phone.
PRODUCT IDENTIFICATION Log Set SAFETY DEVICE This heater has a pilot with an Oxygen Depletion Sensing (ODS) safety shutoff system. The ODS/pilot is a required feature for vent-free room heaters. The ODS/pilot shuts off the heater if there is not enough fresh air. IGNITION SYSTEM This heater has an electronic ignitor to light heater fuel supply.
AIR FOR COMBUSTION AND VENTILATION Continued Unusually Tight Construction The air that leaks around doors and windows may provide enough fresh air for combustion and ventilation. However, in buildings of unusually tight construction, you must provide additional fresh air. Unusually tight construction is defined as construction where: a.
AIR FOR COMBUSTION AND VENTILATION Continued A. Rework worksheet, adding the space of an adjoining room. If the extra space provides an unconfined space, remove door to adjoining room or add ventilation grills between rooms. See Ventilation Air From Inside Building. B. Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 7. C. Install a lower Btu/Hr heater, if lower Btu/Hr size makes room unconfined.
INSTALLATION NOTICE: This heater is intended for use as supplemental heat. Use this heater along with your primary heating system. Do not install this heater as your primary heat source. If you have a central heating system, you may run system’s circulating blower while using heater. This will help circulate the heat throughout the house. In the event of a power outage, you can use this heater as your primary heat source. WARNING: Installation and repair should be done by a qualified service person.
INSTALLATION Minimum Noncombustible Material Clearances Continued If Not Using Mantel INSTALLATION AND CLEARANCES FOR VENT-FREE OPERATION WARNING: Maintain the minimum clearances. If possible, provide greater clearances from floor, ceiling, and adjoining wall. LOG SIZING REQUIREMENTS Log Minimum Firebox Size Height 24" 17" 24" Depth Front Rear * Width Width 14" 28" 20 1/4" Minimum Firebox with Blower 17" 14" 34" 22 3/8" * Measured at 14" depth. Carefully follow the instructions below.
INSTALLATION 10" Continued 8" Mantel Shelf Underside of Mantel Shelf 6" MANTEL CLEARANCES 2 1/2" In addition to meeting noncombustible material clearances, you must also meet required clearances between fireplace opening and mantel shelf. If you do not meet the clearances listed below, you will need a hood.
INSTALLATION Continued INSTALLING HEATER BASE ASSEMBLY WARNING: You must secure this heater to fireplace floor. If not, heater will move when you adjust controls. Moving heater may cause a gas leak. WARNING: If installing in a sunken fireplace, special care is needed. You must raise the fireplace floor to allow access to heater control panel. This will insure adequate air flow and guard against sooting and controls being damaged. Raise fireplace floor with noncombustible material. Make sure material is secure.
INSTALLATION Continued CONNECTING TO GAS SUPPLY WARNING: This appliance requires a 1/2" NPT (National Pipe Thread) inlet connection to the pressure regulator. WARNING: A qualified service person must connect heater to gas supply. Follow all local codes. CAUTION: For propane/LP gas, never connect heater directly to the propane/LP supply. This heater requires an external regulator (not supplied). Install the external regulator between the heater and propane/LP supply.
INSTALLATION CHECKING GAS CONNECTIONS Continued We recommend that you install a sediment trap in supply line as shown in Figure 13. Locate sediment trap where it is within reach for cleaning. Install in piping system between fuel supply and heater. Locate sediment trap where trapped matter is not likely to freeze. A sediment trap traps moisture and contaminants. This keeps them from going into heater controls. If sediment trap is not installed or is installed wrong, heater may not run properly.
INSTALLATION Continued Test Pressures Equal To or Less Than 1/2 PSIG (3.5 kPa) 1. Close equipment shutoff valve (see Figure 14). 2. Pressurize supply piping system by either opening propane/LP supply tank valve for propane/LP gas or opening main gas valve located on or near gas meter for natural gas, or using compressed air. 3. Check all joints from gas meter for natural or propane/LP supply to equipment shutoff valve (see Figure 15 or 16). Apply a noncorrosive leak detection fluid to all joints.
INSTALLATION Crossover Log #6 Continued 1. Place middle log (#1) onto log alignment screw located near the center of base, and in place over log support bracket as shown in Figures 17 and 18. 2. Place front log (#2) onto base. Position log onto two alignment screws to the front of base (see Figure 18). 3. Place left side log (#3) onto two log alignment screws on left side of base (see Figure 18). 4. Place right side log (#4) onto two log alignment screws on right side of base (see Figure 18). 5.
OPERATING HEATER FOR YOUR SAFETY READ BEFORE LIGHTING WARNING: If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life. A. This appliance has a pilot which must be lighted by hand. When lighting the pilot, follow these instructions exactly. B. BEFORE LIGHTING smell all around the appliance area for gas. Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor.
OPERATING HEATER Continued Pilot Burner 5. Turn control knob counterclockwise to the PILOT position. Press in control knob for five (5) seconds (see Figure 21). Note: You may be running this heater for the first time after hooking up to gas supply. If so, the control knob may need to be pressed in for 30 seconds or more. This will allow air to bleed from the gas system. 6. With thermostat control knob pressed in, press and release ignitor button. This will light pilot.
INSPECTING BURNERS Check pilot flame pattern and burner flame patterns often. PILOT FLAME PATTERN Figure 24 shows a correct pilot flame pattern. Figure 25 shows an incorrect pilot flame pattern. The incorrect pilot flame is not touching the thermocouple. This will cause the thermocouple to cool. When the thermocouple cools, the heater will shut down.
CLEANING AND MAINTENANCE WARNING: Turn off heater and let cool before cleaning. CAUTION: You must keep control areas, burners, and circulating air passageways of heater clean. Inspect these areas of heater before each use. Have heater inspected yearly by a qualified service person. Heater may need more frequent cleaning due to excessive lint from carpeting, pet hair, bedding material, etc. WARNING: Failure to keep the primary air opening(s) of the burner(s) clean may result in sooting and property damage.
TROUBLESHOOTING WARNING: Turn off heater and let cool before servicing. Only a qualified service person should service and repair heater. CAUTION: Never use a wire, needle, or similar object to clean ODS/pilot. This can damage ODS/pilot unit. Note: All troubleshooting items are listed in order of operation. OBSERVED PROBLEM POSSIBLE CAUSE REMEDY When ignitor button is pressed, there is no spark at ODS/pilot 1. Ignitor electrode not connected to ignitor cable 2. Ignitor cable pinched or wet 1.
TROUBLESHOOTING Continued OBSERVED PROBLEM POSSIBLE CAUSE REMEDY ODS/pilot lights but flame goes out when control knob is released 1. Control knob not fully pressed in 2. Control knob not pressed in long enough 1. Press in control knob fully 2. After ODS/pilot lights, keep control knob pressed in 30 seconds 3. Wait one minute for safety interlock system to reset. Repeat ignition operation 4. Fully open equipment shutoff valve 5. A) Contact local natural or propane/LP gas company 3.
TROUBLESHOOTING Continued OBSERVED PROBLEM POSSIBLE CAUSE REMEDY Slight smoke or odor during initial operation 1. Residues from manufacturing processes and logs curing 1. Problem will stop after a few hours of operation Heater produces a whistling noise when burners are lit 1. Turning control knob to HI position when burners are cold 2. Air in gas line 1. Turn control knob to LO position and let warm up for a minute 2. Operate burners until air is removed from line.
TROUBLESHOOTING Continued WARNING: If you smell gas • Shut off gas supply. • Do not try to light any appliance. • Do not touch any electrical switch; do not use any phone in your building. • Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. • If you cannot reach your gas supplier, call the fire department. IMPORTANT: Operating heater where impurities in air exist may create odors.
OPTIONAL POSITIONING OF THERMOSTAT SENSING BULB FOR MASONRY AND FACTORYBUILT METAL FIREPLACE If your log set cycles to pilot, but the room temperature drops to a lower than ideal comfort level before the log set comes back on, you may want to reposition the thermostat sensing bulb. The thermostat sensing bulb is located on the left side of the base assembly. This location allows the thermostat to keep the room temperature at an ideal comfort level for most fireplace applications.
SPECIFICATIONS CDR3924PT Btu (Variable) 11,000/39,000 Type Gas Propane/LP Ignition Electronic Manifold Pressure 8.0" W.C. Inlet Gas Pressure (in. of water) Maximum 14" Minimum* 11" Shipping Weight 30 lbs. * For purpose of input adjustment CDR3924NT 11,000/39,000 Natural Electronic 3.6" W.C. 10.5" 5" 30 lbs. ACCESSORIES NOTICE: All accessories may not be available for all fireplace models. Purchase these heater accessories from your local dealer.
ILLUSTRATED PARTS BREAKDOWN MODELS CDR3924PT AND CDR3924NT 13 9 5 7 17 6 4 8 20 14 27 15 27 1 19 10 25 23 26 11 3 22 21 16 12 24 2 18 33 31 29 32 30 28 26 www.desatech.
PARTS LIST This list contains replaceable parts used in your heater. When ordering parts, follow the instructions listed under Replacement Parts on page 25 of this manual. KEY PART NUMBER NO.
WARRANTY INFORMATION KEEP THIS WARRANTY Model Serial No. Date Purchased Always specify model and serial numbers when communicating with the factory. We reserve the right to amend these specifications at any time without notice. The only warranty applicable is our standard written warranty. We make no other warranty, expressed or implied.