Suburban Airxcel Suburban NT-16SEQ

This document is a user's information manual for the NT-16SEQ and NT-20SEQ Suburban furnaces, designed for use in recreational vehicles (RVs). It provides comprehensive instructions for safe operation, maintenance, and troubleshooting. The manual emphasizes safety warnings related to fire, explosion, carbon monoxide poisoning, and general appliance hazards. It is intended for both installers and consumers, with a strong recommendation for consumers to retain it for future reference and to contact a qualified service center for any further information or repairs.

Function Description

The Suburban NT-16SEQ and NT-20SEQ furnaces are heating appliances designed to provide warmth within an RV. They operate by burning propane gas to generate heat, which is then circulated throughout the vehicle by a blower. The furnace is equipped with an automatic ignition device, eliminating the need for manual lighting of the burner. A thermostat controls the operation, allowing users to set a desired room temperature. The furnace is designed to vent combustion products to the outside atmosphere and draw combustion air from outside, preventing the infiltration of harmful gases into the living space.

Usage Features

The manual outlines a clear, step-by-step procedure for operating the furnace, emphasizing safety at each stage.

Pre-Operation Safety Checks: Before starting the furnace, users are instructed to ensure the vehicle is stationary (not in motion or being towed) and that all ignition systems are "OFF" during refueling. A critical safety step is to check for gas leaks by smelling around the appliance area, especially near the floor, as propane is heavier than air. If gas is detected, immediate evacuation, shutting off the gas supply, avoiding electrical switches, and contacting a qualified service technician or fire department are mandatory.
Starting Procedure: To initiate heating, the manual gas valve (if equipped) or the valve at the outside propane tank must be turned to the "OFF" position initially. The thermostat is then set above room temperature to activate the blower. A slight delay is expected before the blower starts, and it should run for 5 minutes for a combustion chamber purge cycle. If the blower fails to start or stops prematurely, users are advised to shut down and contact a service agency. After the purge cycle, the thermostat lever is moved below room temperature, allowing the blower to run for approximately 2 minutes before turning off. This sequence helps clear any residual gas.
Gas Supply and Ignition: After the purge cycle and ensuring no gas smell, the manual shut-off valve or propane tank valve is opened fully. The furnace is designed to light automatically within 30 seconds of the blower turning on, using its ignition device. Manual lighting is strictly prohibited. If the burner does not light after three attempts, users are instructed to shut down the furnace and contact a service agency, avoiding further attempts to cycle the furnace through the thermostat.
Thermostat Control: Once the furnace is operational, the thermostat can be set to the desired temperature. The furnace will cycle on and off to maintain this setting.
Shut Down Procedure: To turn off the furnace, the thermostat is set to its lowest setting, then moved to the "OFF" position. All electric power to the appliance should be turned off if service is to be performed. Finally, the manual shut-off valve is turned clockwise to the "OFF" position, without forcing it.
Ventilation Awareness: Users are warned against installing screens over the vent, as this can restrict airflow and lead to unsafe operation. It is also crucial to ensure that the furnace vent is not blocked by any part of the RV, such as an open door, and that combustion air flow and warm air circulation are not restricted. The manual explicitly states that the furnace should not be operated if the vent is covered, for instance, by add-on rooms, screen porches, or patios, as this could lead to combustion products entering occupied areas.

Maintenance Features

The manual places significant emphasis on regular maintenance to ensure safe and efficient operation.

Monthly and Annual Inspections: Owners are advised to inspect the furnace monthly during the heating season for soot on the vent. Soot indicates incomplete combustion and an unsafe operating condition, requiring immediate shutdown and contact with a qualified service agency. An annual inspection by a qualified service person is recommended before each heating season, with particular attention to furnace installation, vent termination, chamber, venting, ducting, and gas piping for signs of deterioration or damage.
Cleanliness: Keeping the furnace clean is paramount. Control compartments, burners, and circulating air passageways must be free of lint, dust, and other debris. More frequent cleaning may be necessary if the RV has carpeting or bedding materials that produce excessive lint. The area around the furnace must be kept clear of combustible materials, gasoline, and other flammable vapors and liquids.
Burner Inspection and Cleaning: Periodically, the main burner flame should be observed to ensure it is burning with a hard blue flame and well-defined burner ports. A yellow or lazy flame indicates incomplete combustion, possibly requiring burner cleaning or replacement. Instructions are provided for accessing the main burner by removing four screws from the burner access door. If excessive rust or corrosion is present, the burner should be thoroughly cleaned with a steel wire brush and high-compression air or replaced. This task should be performed by a qualified service person.
Combustion Chamber Cleaning: The manual describes a procedure for cleaning the combustion chamber, which involves removing the furnace from the cabinet, and detaching the manifold blower assembly and controls. Compressed air is then used to blow through the chamber to remove soot or loose debris. This is a more involved maintenance task likely requiring professional assistance.
Gasket Integrity: All gaskets should be inspected for signs of leakage or deterioration and replaced if necessary, as safe operation depends on tight seals.
Return Air Inlet: Return air inlet openings to the furnace must be inspected to ensure they are free of restrictions, allowing adequate airflow.
Professional Service: The manual repeatedly stresses that installation, adjustment, alteration, service, and maintenance must be performed by a qualified service agency or the gas supplier. Users are explicitly warned against attempting to repair damaged parts or the furnace themselves.
Lubrication: The furnace motor is permanently lubricated and does not require oiling.

By following these detailed instructions, users can ensure the safe and effective operation of their Suburban NT-16SEQ and NT-20SEQ furnaces, minimizing risks and extending the appliance's lifespan.