Dometic DFMD30111 Medium Furnace User Manual

Product Overview

The Dometic DFMD30111 Medium Furnace is a low-profile, quiet LP gas furnace designed for efficient heating in RVs and trailers. This model replaces the previous 8500 series, offering superior air delivery and easy maintenance. It is a 12V DC powered unit.

Key features include a powerful heating capacity of 30,000 BTUs, an efficient airflow design that maximizes air distribution to reduce hot and cold spots, and quiet operation due to reduced air turbulence. Its compact design measures 7-3/8 inches H x 16-1/2 inches W x 20 inches D, allowing for versatile installation in horizontal or vertical configurations.

Image: The Dometic DFMD30111 Medium Furnace, showcasing its compact design and front panel.

Specifications

Image: Dimensions of the Dometic DFMD30111 Medium Furnace, showing height, width, and depth measurements.

Installation and Setup

The Dometic DFMD30111 furnace is designed for straightforward installation, though professional installation is recommended for LP gas appliances. It can be mounted either vertically or horizontally, offering flexibility for various RV and trailer layouts.

Pre-Installation Considerations:

• Ensure the existing cutout in your RV or trailer can accommodate the furnace dimensions (7-3/8" H x 16-1/2" W x 20" D). This model is slightly deeper than the older 8500 series.
• An access door and thermostat are sold separately and are required for full functionality and proper installation.
• Verify that the 12V DC power supply is adequate for the furnace's operation.
• The gas connector location has been moved to the top of the heater from the side compared to some older models. Plan gas line routing accordingly.

General Installation Steps (Consult full installation manual for detailed instructions):

1. Prepare the mounting location, ensuring it is clean and clear of obstructions.
2. Carefully position the furnace in the cutout, ensuring proper alignment for the exhaust and intake vents.
3. Connect the LP gas line to the furnace. Ensure all connections are secure and leak-free.
4. Connect the 12V DC power supply wires to the furnace's electrical terminals.
5. Install the separately purchased access door and thermostat, following their respective instructions.
6. Perform a system check to ensure proper operation and verify there are no gas leaks.

Operating Instructions

The Dometic DFMD30111 furnace operates via a standard RV thermostat (sold separately). Once properly installed and connected to an LP gas supply and 12V DC power, the furnace is ready for use.

To Operate the Furnace:

1. Ensure your RV's LP gas supply is turned on and there is sufficient gas in the tank.
2. Verify that the 12V DC power supply to the furnace is active.
3. Set your RV's thermostat to the desired temperature.
4. The furnace's blower will activate first, followed by the ignition of the burner.
5. The furnace will cycle on and off as needed to maintain the set temperature.

Important Operating Notes:

• The furnace is designed for quiet operation, but some fan noise during startup and shutdown is normal.
• Allow the furnace to run for a period to evenly distribute heat throughout the vehicle, especially after initial startup or prolonged periods of inactivity.
• If the furnace fails to ignite after several attempts, it may enter a lockout mode. Refer to the troubleshooting section.

Maintenance

Regular maintenance ensures the longevity and efficient operation of your Dometic furnace. The DFMD30111 is engineered for easy maintenance.

Routine Maintenance Checks:

• Clean Air Intake/Exhaust Vents: Periodically inspect and clean the exterior air intake and exhaust vents to ensure they are free from obstructions (e.g., dirt, debris, insect nests). Blockages can impair performance and safety.
• Inspect Ductwork: Ensure all internal ductwork connected to the furnace is secure and free of leaks to maximize heating efficiency.
• Check Electrical Connections: Annually, or if issues arise, inspect all 12V DC electrical connections for tightness and corrosion.
• Gas Line Inspection: Periodically check the LP gas line and connections for any signs of leaks or damage. Use a gas leak detector or soapy water solution.
• Professional Servicing: It is recommended to have the furnace inspected and serviced by a qualified RV technician at least once a year, especially before the heating season. This includes checking the burner, heat exchanger, and ignition system.

Winterization:

Before storing your RV for the winter, ensure the LP gas supply is turned off and the furnace is completely shut down. No specific winterization steps for the furnace itself are typically required beyond ensuring it is off and protected from extreme elements if exposed.

Troubleshooting

This section provides basic troubleshooting steps for common issues. For complex problems, consult a qualified technician.

Proposition 65 Warning: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Warranty and Support

Specific warranty details for the Dometic DFMD30111 Medium Furnace are typically provided with the product documentation at the time of purchase. Please refer to the warranty card or the official Dometic website for the most current and detailed warranty information.

For technical support, service, or to locate an authorized service center, please visit the official Dometic website or contact Dometic customer service directly. Contact information can usually be found in the product packaging or on their official website.

You can visit the Dometic store on Amazon for more products and information: Dometic Store