RV Furnace Won’t Ignite – 10 Items to Check

You love traveling around the country in an RV. Everything you need for a comfortable and fun trip is conveniently packed inside. In the winter, the RV’s furnace keeps you warm when you’re driving and sleeping at night.

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Unfortunately, sometimes the RV furnace won’t ignite. It’s not a problem you want to ignore. You can wear more layers and burrow under blankets for warmth. It’s not ideal, but you won’t freeze. However, the furnace in your recreational vehicle does more than keep you toasty warm. It also prevents pipes and taps from freezing and bursting in cold temperatures. A busted pipe is expensive to fix and this doesn’t include the costs associated with cleaning up any damages.

Before you leave on any winter trip, always check the vehicle’s furnace.

Reasons Your Furnace Won’t Ignite

There are a few reasons why your furnace won’t ignite. Some are simple fixes and others may require help from a professional.

1) Problems with the Propane Tank

Propane tanks are a common fuel source for RV furnaces. You can easily swap the empty tanks out for full ones at most gas stations on the road. A common problem with the tanks is a closed valve preventing gas from flowing through the line to the furnace.

Older tanks and ones with low fuel levels can also freeze in cold temperatures. Recycled propane tanks can also fail to deliver gas to the furnace. Often the problem is due to a clogged valve. Manufacturers sometimes repaint recycled tanks and the paint can temporarily block the main tank valve.

2) Problems with the Propane Line

When the propane tank’s main valve is open and there isn’t a problem with the regulator. It’s the small device near the tank that controls fuel flow. The next step is to check the line. Chances are air has gotten into the line. It can create a blockage preventing fuel from reaching the furnace.

The coupler can also loosen in cold weather allowing the gas to escape. Gaskets can also wear out, resulting in leaks. Either of these issues will prevent the RV furnace from igniting.

3) A Burned Out Thermocouple and Pilot Light

The thermocouple is a small tube in the center of the pilot light and provides the electricity needed to keep the gas valve open. The small part does wear out over time, though the brass tubes are designed to last for years. When the tube is worn out or broken it can’t detect the flame from the pilot light keeping the gas line valve closed.

Soot and dirt can also block the pilot light preventing the flame from being detected by the thermocouple. It can also cause the flame to continuously go out. The low flame or lack of a consistent one isn’t enough to engage the thermocouple.

4) Problems with the Thermostat

Without a thermostat, the furnace doesn’t know when to turn on and off. It is the “brains” behind the RV’s heating system. The component and the small parts inside do break down, but it usually takes several years. Thermostats are designed to withstand a lot of use.

Some are battery-powered. Always check the batteries if this applies to yours. Loose wires are another reason your thermostat could be giving you problems. You could also have corrosion around the connecting wires. Any of these issues will cause problems with your thermostat.

5) Problems with Airflow

There are two main reasons why your heater is running but you’re not feeling the warm air. It is usually either the fan’s motor or loose wiring. Older fans can have worn out bushings or bearings. The fan’s motor will be warm, only it’s not pushing out the hot air. Also, check the fan blades. Dirt and debris can collect inside to prevent the blades from rotating.

Loose or broken wires will also cause problems with airflow. A loose wire will slow the fan down or cause it to run intermittently. Broken wires will stop the fan blades so only a small amount of heat is released into the RV.

6) Simple Electrical Issues

Along with wiring problems, electrical problems with your furnace are also caused by tripped circuit breakers and low onboard batteries. A low or depleted battery won’t have the power to ignite the heating system or control the thermostat. A tripped circuit breaker will prevent the electrical spark needed to light the pilot light.

How to Fix An RV Furnace That Won’t Ignite

You can fix some RV furnace issues at a gas station or when you stop for the day. Others will require a licensed electrician. Preferably one with experience working with RV heating systems.

Is It The Problem With The Propane Tank Gas Lines?

Propane gas lines are prone to air bubbles. It’s a good idea to bleed the lines every time you install a new propane tank. Gaskets and couplings will loosen over time. The small components can also break.

How to Fix a Problem With a Propane Tank or Gas Line

Air pockets in propane gas lines are a common problem, and easy to fix. Referred to as bleeding the line, you start by pressing the control knob on the valve and the ignitor button simultaneously. It can take up to 10 minutes of repeated tries before the air is removed and the pilot light ignites.

You can temporarily fix some propane gas line leaks by wrapping a rag or towel around the spot. If the leak is due to a hole in the line, you need to replace the part. The same applies to a broken coupler or gasket. You can tighten the components if they’re loose without calling an expert. However, if you need to replace any part it’s probably not a DIY job unless you’re familiar with the RV’s furnace.

Minor Electrical Problems Can Cause Ignition Failure

A loose wire or connection, along with dirt and soot, can cause small electrical problems. Some are simple fixes. It can be anything from tightening a loose wire to replacing a small component like a battery. These minor electrical problems are inconvenient, especially when it’s cold outside. The good news is, it doesn’t take long to repair and it’s often inexpensive.

A Wiring Problem Could Prevent Electricity From Igniting the Furnace

The pilot light needs a low-voltage spark to ignite. When you’re not receiving enough power to ignite the furnace, it’s time to start following the various wires. Look for any loose connections. Traveling over bumpy roads can result in loose wires. You also want to check for any bends or crimps. These can stop power from reaching the pilot light.

Loose wires are easy to tighten if they’re screwed in. You only need a compatible screwdriver to tighten the loose screw. Other wires are soldered, and this is a little more difficult to repair. The soldering often needs to be redone. You may need a professional RV electrician to tighten or replace soldered wires.

Dealing With a Low or Dead Onboard Battery

Using a multimeter, you can measure the number of volts the furnace is receiving. Ideally, you want around 10.5 volts. It’s enough to power the fan, thermostat, and ignite the pilot light. Anything less than 10-volts and you’ll notice a problem with your furnace’s performance.

When your battery is low or dead, hopefully, you have a backup. It’s a good thing to have in every RV emergency roadside kit. You can connect the engine’s 12-volt battery. It has more than enough voltage to ignite the furnace. The downside is draining the engine’s battery.

Battery Corrosion Can Interrupt Service

It’s a common problem with older batteries. Electrolytic corrosion can build up on battery terminals. The gray, white, or greenish material can block power from the battery to the pilot light. Usually, cleaning the terminals will resolve the problem.

It only takes five steps to clean corroded battery terminals.
  1. Mix a thick paste of baking soda and water.
  2. Disconnect the wires from the terminals.
  3. Using an old toothbrush dipped in the baking soda paste, carefully scrub the corroded material off of the terminals.
  4. Wipe the battery terminals clean with a paper towel or rag.
  5. Reconnect the wires to the battery terminals.

You should have power to the furnace and thermostat.

A Damaged Wire Can Cause a Furnace Not To Ignite

A damaged wire will prevent your furnace from igniting. The only solution is to replace the wire. It’s also something you can do yourself, even when you’re out on the road. Truck stops and businesses that cater to RVers often sell replacement furnace wire.

Along with the wire, you also need a pair of cutters.
  • Using the wire cutters, remove the damaged piece and about an inch of the protective coating around the wire.
  • Remove the coating around the replacement wire, leaving an inch or so of wire exposed.
  • Twist the two sections of wires together. If you want to ensure the wires won’t slip apart, you can also solder them.

The last step is to reconnect the wire to the furnace.

A Thermostat Problem Could Cause a Failure in The Propane System

Without the thermostat, the furnace wouldn’t know when to turn on or off. The small component is essential to the furnace. Everything else can work great, but it doesn’t matter when the thermostat is bad.

Thermostats are designed to last for years, but they do give out. Sometimes it’s an easy fix like a dead battery or loose wire. Other times it’s the sensor, and this means you need to replace the thermostat.

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Check and Tighten Any Loose Wires on the Thermostat

It’s easier to tell with a digital thermostat when a wire is loose. The digital numbers often flash or display obviously inaccurate temperature readings. It’s not hard to check the connections. Remove the front plate and tighten the small screws that hold the wires in place.

Checking and Replacing Internal Thermostat Batteries

Not all RV thermostats are connected to the engine’s 12-volt battery. Some can with disposable batteries. When battery power is running low or gone, the thermostat won’t display temperature settings. The control buttons also won’t respond. Replacing the batteries should resolve the problem. It’s also a good idea to clean the battery terminals. The problem can also be corrosion.

Tips for Staying Warm in a Furnace Emergency

There are a few things you can do to prepare for a furnace emergency. Hanging heavy curtains in the windows is an inexpensive way to block cold air drafts. It also helps to conserve energy when the furnace is working. You can also double cover the windows. Combined with the curtains, you won’t have drafty windows.

Your RV has several vents. The vents are necessary but also let in cold air. Some RVs come with vent covers, others are optional. It is worth the investment. The covers are easy to install and take off. They’ll also help you stay warm without a working furnace.

Cold air also sweeps in from the floor. The vehicle is raised off the ground. The space underneath the motor home allows cold air to gather and seep into the cabin and living area. An RV skirt will help keep your floors warmer and stop some drafts.

Routine Maintenance for Your RV’s Furnace

Simple maintenance is the best way to ensure you have heat on winter trips. Always bleed the propane gas lines before you start on your drive. Even sitting idle for a few months can allow air to build up.

You also want to check all of the connections and wires. Don’t forget to clean battery terminals, both in the engine and some types of thermostats.

Along with routine inspections, you also want to dry out a heavy-duty vacuum. Sweep around the furnace and the ducts. Clean the duct vents, along with the intake and exhaust valves. These steps don’t guarantee the furnace won’t fail, but they lessen the chances.

Bottom Line – Heat It Up

Your RV furnace is similar to the one in your home. It comes with several components that can fail. Routine maintenance is the best way to prevent furnace failure, but wear and tear can cause an unexpected problem.

Keep an extra battery on the RV, along with wire. Extra blankets and heavy curtains are also a good idea. Don’t be afraid to splurge on extras like vent covers and RV skirts. You’ll be glad you did when the furnace goes out on your winter camping trip.

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