A Foolproof Guide on How to Light a Furnace

Since furnaces are powered all day and night during the wintertime, there’s a greater chance that they’ll act up; leaving you shivering in the cold.

In this guide, we teach you how to light a furnace in a few simple steps. We’ve also added a few tips that’ll keep your RV furnace running for months!

How to Manually Light an RV Furnace

Now that you have a basic idea of how an RV furnace functions to warm up its surroundings, you can easily follow basic directions on how to light it up. Here’s a step-by-step procedure on how to light an RV furnace.

1. Read the Manual

The RV furnace will usually have an instruction manual that details how to light it in case it goes out or malfunctions. Make sure to keep the manual somewhere safe (preferably near the furnace) so that it’s easier to find in an emergency.

2. Vacuum the Residual Gas

Like all electrical appliances, an RV furnace has a dial system to turn it on and off. It is usually located at the thermostat and has knobs for ‘auto’, ‘pilot’, and ‘heat mode’. Turn the dial to ‘auto’ and then, select ‘heat mode’ so it turns on and starts the process of vacuuming out residual gas.

3. Light Up a Flame

When the gas is released, switch the dial to ‘pilot’. Next to it, you’ll find a reset button — hold it and light up the flame using a lighter. Release the hold.

What Causes an RV Furnace Not to Ignite?

An RV furnace can go out for a lot of reasons, but luckily, many of them can be fixed easily. Here are a few common ones:

Insufficient Battery Voltage

An electric furnace is powered by a 12v battery. If the power supply is insufficient or lower than 10.5v, the propane won’t ignite. Use a multimeter and check the voltage of the battery. Get a new one if it is reading low.

Dirty Filters

A furnace’s filters need to be cleaned out often, especially in the wintertime. If they’re dirty or clogged up, it could affect the airflow to the ducts and prevent the furnace from igniting. A simple rinse and ventilation is sufficient.

Malfunctioning Thermostat

The thermostat needs to be adjusted higher than the room’s temperature for it to work. If it fails to run the furnace, you could try and drop the room temperature a couple degrees using a portable fan. If it still does not work, try replacing it or have a professional check it out.

Split Gas Ducts

The functioning of a furnace heavily depends on the gas supply system to ignite the propane using fuel and exhaust warm air through the ducts. Check if the gas valves are obstructed or the heating ducts are cut in any way. If there’s a propane leak, open all the doors, move out and call a professional.

Tips to Keep in Mind When Lighting an RV Furnace

Lighting a mobile home’s furnace is easy but requires a concentrated eye as a nick out of place can call for an emergency. Here are some tips to keep in mind:

  • Get a propane detector such as the MTI Safe-T-Alert 20 Series Propane/LP Gas detector to check for any gas leakages and a propane regulator like the Camco two stage to protect against overpressure.
  • Do not cover the vents while the furnace is powered on, this ensures the heating ducts can safely expel warm air in the RV.
  • Make sure to hear the blower motor turn on as the furnace is ignited, it should only take a couple seconds or at most five minutes to regulate the temperature – even if it’s pre-set. 
  • Keep your nose on alert for burning smells. If it’s dusty, the filters need to be cleaned out and if it’s a gas leak, immediately open all windows and doors and evacuate the premises.
  • Ensure the burner is getting enough airflow so fuel can be efficiently burned. You’ll see soot accumulating on the exhaust vent if the airflow is obstructed.

How to Maintain an RV Furnace

Here are some regular maintenance steps you can take to ensure the furnace runs properly:

  • Clean out the heating ducts and valves at least twice a year
  • Check for minor leaks in the propane heater
  • Clear out soot from the exhaust vents

Parts of an RV Furnace Everyone Should Know About

A furnace acts as the main heat source in an RV. It’s important to familiarize yourself with the names and functions of each part of the RV furnace so in case it malfunctions, you’ll know what to look for.


RV furnaces usually employ battery-powered thermostats to run the system. They may also be analog or digital. As the electrical wiring and voltage is set differently in an RV, standard household 24v thermostats cannot be used. A thermostat works to start and stop the HVAC system and adjust temperatures.

Circuit/Control Board

Once the thermostat is turned on, the control board of the RV furnace receives a signal which powers it on. The circuit functions as the ‘brain’ of the furnace and controls the ignition, flame sensors, gas valves and blower fans.


From the control board, the signal is sent to a relay system which balances the current passed and optimises it to run the fans at high speed. This indicates the furnace has turned on.

Blower Motor

A blower motor (the main functional part of the furnace) is responsible for projecting warm air that is created with the help of every motor into the home through a duct via high-speed fans.

Sail Switch

The sail switch works as a safety function and is responsible for turning on the blower motor, detecting when the warm air is ready to be pushed through the duct, and keeping the heat fans running at a consistent speed. It also turns off the furnace if the battery tank isn’t sufficient enough to run the blower.

High-Limit Switch

The high limit switch, also a safety dial, functions similar to a heat sensor, i.e it balances the temperature of the furnace and keeps it from overheating.

Gas Valve

Gas valves in an RV are modified to receive electricity, once the safety switches have regulated the blower motor and heating. The flow of electricity ignites the electrode and heating begins.


Located in the combustion changer, the ignitor powers on after receiving 10.5v current signals from the circuit board’s ignition centre or module. It turns fuel into heat and lights up the RV furnace.

Heating Ducts

Once the blower fans start running and the ignitor lights up the furnace, the hot air is expelled out through the heating ducts. The temperature can be pre-set via the thermostat.

checking rv heater

Frequently Asked Questions

Can you manually light an RV furnace?

Yes, RV furnaces can be lighted manually, but most modern models have a touch sensor to light and turn off the power. If they malfunction, you could try to manually ignite the furnace to heat up the RV. For an aged furnace, manual lighting is the only option.

What would cause an RV furnace not to ignite?

An insufficient battery tank can restrict an RV furnace from igniting the propane. The battery tank is designed to run on 10.5v so any less voltage can fail to ignite the furnace. Dirty or obstructed filters and heating ducts can also cause the furnace to stop working.

Why is my furnace not kicking on?

If your furnace isn’t working, in short, a part may be broken or malfunctioning. First, check for dirty filters as they can restrict airflow and prevent the furnace from functioning. Check if the gas line has turned off or if the battery tank has malfunctioned. Also, see what setting your thermostat is adjusted at.

How do I know if my furnace pilot light is out?

You can usually see the flame from the front cover panel of the furnace. If it isn’t visible, it’s probably out, and if it won’t light, it has malfunctioned. The flame is usually blue in color (the same as a gas stove).

Will gas leak if the pilot light goes out?

In short, no. Most modern furnaces are equipped with fail-safe sensors on the pilot light that are responsible for turning the gas off as soon as the pilot light goes out. If there isn’t a sensor installed, the furnace may still only be blowing cold air and won’t be leaking gas.

Brief Summary

Furnaces are essential to surviving in the wintertime, especially if you plan to camp with your RV above sea level. If you have a furnace in your home on wheels, you at least need to know how to light a furnace and what to do if it malfunctions. We hope this guide has been helpful!


Beau is an electrical engineer with a knack for DIY repair and construction. When he's not tinkering with his projects he's on the road travelling and enjoying an exciting lifestyle with his young family.

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