UNVENTED (VENT-FREE) GAS LOG HEATER OWNER’S OPERATION AND INSTALLATION MANUAL Models VF-18N-MHD, VF-18P-MHD, VF-24N-MHD and VF-24P-MHD 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 a 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 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 (propane/LP units only). 3.
Local Codes Install and use heater with care. Follow all local codes. In the absence of local codes, use the latest edition of The National Fuel Gas Code ANSI Z223.1/NFPA 54*. *Available from: American National Standards Institute, Inc. 1430 Broadway New York, NY 10018 National Fire Protection Association, Inc. Batterymarch Park Quincy, MA 02269 Unpacking CAUTION: Do not remove the data plates from the grate assembly. The data plates contain important warranty and safety information. 1.
air for combustion and ventilation 1. Continued Unusually tight construction is defined as construction where: a. walls and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating of one perm (6 x 10-11 kg per pa-sec-m2) or less with openings gasketed or sealed and b. weather stripping has been added on openable windows and doors and c.
air for combustion and ventilation Continued If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space is an unconfined space. You will need no additional fresh air ventilation. WARNING: If the area in which the heater may be operated is smaller than that defined as an unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.
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: A qualified service person must install heater. Follow all local codes.
Installation Continued Example installation and clearances for vent-free operation WARNING: Maintain the minimum clearances. If you can, provide greater clearances from floor, ceiling and adjoining wall.
INSTALLATION Continued Noncombustible Material Distance (A) Requirements for Safe Installation 12" or more Noncombustible material OK Between 8" and 12" Install fire place hood accessory ( see Accessories, page 25). Less than 8 Noncombustible material must be extended to at least 8". See Between 8" and 12", above. If you cannot extend material, you must operate heater with flue damper open. Figure 5 - Heat Resistant Material (Slate, Marble, Tile, etc.
INSTALLATION Continued Mantel Clearances In addition to meeting noncombustible material clearances, you must also meet required clearances between fireplace openings and mantel shelf on each side of the fireplace. If you do not meet the clearances listed below, you will need a hood. Determining Minimum Mantel Clearance If you meet minimum clearance between mantel shelf and top of fireplace opening, a hood is not required (see Figure 6, page 10).
INSTALLATION Continued Installation Items Needed • control cover kit (provided with heater) • approved flexible gas hose (if allowed by local codes) • sealant (resistant to propane/LP gas, not provided) 1. Apply pipe joint sealant lightly to male threads of gas fitting (not provided). Connect approved flexible gas hose to inlet side of gas control (see Figure 10). IMPORTANT: Hold gas fitting with wrench when connecting flexible gas hose. 2. Position heater assembly in fireplace. 3. Connect to gas supply.
INSTALLATION Continued Installation must include an equipment shutoff valve, union and plugged 1/8" NPT tap. Locate NPT tap within reach for test gauge hook up. NPT tap must be upstream from heater (see Figure 12). IMPORTANT: Install equipment shutoff valve in an accessible location. The equipment shutoff valve is for turning on or shutting off the gas to the appliance. Check your building codes for any special requirements for locating equipment shutoff valve to fireplaces.
Installation Continued 4. Check all joints of gas supply piping system. Apply noncorrosive leak detection fluid to all joints. Bubbles forming show a leak. 5. Correct all leaks at once. 6. Reconnect heater and equipment shutoff valve to gas supply. Check reconnected fittings for leaks. Test Pressures Equal To or Less Than 1/2 PSIG (3.5 kPa) 1. Close equipment shutoff valve (see Figure 13). 2.
Installation Remote lighting instructions Continued 4. Add lava rock and small decorative logs around base of heater if desired. You may place lava rock and log pieces up to flat burner. DO NOT place rock or logs on front burner or on logs. Placing any material on unit other than ember material on front burner may result in production of carbon monoxide or soot.
Operating Heater Continued 6. Press the buttons and at the same time. A short acoustic signal confirms the start sequence has begun. Further short acoustic signals (0.2 sec., 1 Hz) indicate the ignition process until it is completed and main gas flows. If pilot is already lit, motor will turn on (max. flame height) while buttons are pressed down. If pilot does not light, see Troubleshooting, page 21. 7. Press to turn on main burner and increase flame height.
Operating Heater Continued • Timer: The timer mode (TIMER) operates much like the temperature mode above. The timer setting allows you to set specific times for on and off. (There are 2 burner on and 2 burner off cycles every 24 hours.) If the reading for the nighttime temp. is "– – –", the motor will turn off the valve to standby pilot position and wait for the next burner on cycle. This display shows the setting temperature every 30 seconds.
Operating Heater Continued Lighting with Piezo Ignitor 1. Disconnect ignitor cable from receiver and connect to Piezo Ignitor Tab (see Figure 18, page 17 and Wiring Diagram on page 24). 2. STOP! Read safety information on page 15, 3. Make sure equipment shutoff valve is fully open. 4. Turn Motor-knob clockwise to the OFF position. 5. Wait (5) minutes to clear any gas and then smell for gas around heater and near floor. If you smell gas, STOP! follow "B" on page 14. 6. ON/OFF switch in "—" ON position. 7.
Inspecting Burners Continued BURNER FLAME PATTERN Figure 22 shows correct burner flame pattern. NOTICE: Do not mistake orange flames with yellow tipping. Dirt or other fine particles are burned by heater, causing brief patches of orange flame. If burner flame pattern is incorrect, as shown in Figure 23 • turn appliance off (see To Turn Off Gas to Appliance on page 18 • see Troubleshooting, page 21 Blue & Bright Yellow Flames Cleaning and Maintenance WARNING: Turn off heater and let cool before cleaning.
Cleaning and Maintenance Continued 1. Remove two screws from back of unit that attach main log assembly to base assembly (see Figure 24). 2 . Remove screws from left and right side of front log assembly to remove from base assembly (see Figure 24). 3. Inspect burner and primary air inlet holes on injector holder of each burner for dust and dirt (see Figures 24 and 25). 4. Blow air through the ports/slots and holes in the burner. Main Log Assembly Cleaning Access 5.
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 and are pressed at the same time, there is no spark at ODS/pilot 1. Switch in OFF position (module gives long steady beep) 2.
troubleshooting Continued OBSERVED PROBLEM POSSIBLE CAUSE REMEDY Burner backfiring during combustion 1. Burner orifice is clogged or damaged 1. Clean burner (see Cleaning and Maintenance, page 19) or replace burner orifice 2. Replace damaged burner 3. Replace gas regulator 2. Damaged burner 3. Gas regulator defective Orange flame in burner during burner combustion 1. Not enough air 2. Gas regulator defective 1. Check burner for dirt and debris.
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.
troubleshooting Continued Identifying error signals from receiver OBSERVED PROBLEM POSSIBLE CAUSE REMEDY Long signals (0.8 second tone, 0.2 second break) during ignition Battery nearly down. (When signal appears the first time approximately 10 ignitions left) Replace battery 5 second continuous tone Cable is not connected, ON/OFF switch is in OFF position Connect cables 5 short signals (8.2 second tone, 0.2 second break) Ignition not successful, possible air in supplyline Switch to ON.
Replacement Parts Note: Use only original replacement parts. This will protect your warranty coverage for parts replaced under warranty. Parts Under Warranty Contact authorized dealers of this product. If they can’t supply original replacement part(s), call DESA’s Technical Service Department at 1-866-672-6040.
Illustrated Parts Breakdown Models VF-18N-MHD, VF-18P-MHD, VF-24N-MHD and VF-24P-MHD 30 24 22 27 25 22 32 28 29 20 29 1 28 15 24 27 15 7 15 15 3 21 13 14 15 15 4 15 15 31 23 15 26 6 17 8 11 19 34 12 9 16 10 18 16 15 15 15 15 5 2 33 15 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. PART NUMBER KEY 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.