Rv Furnace Won’t Ignite: Troubleshooting the Furnace (Solved)

The campfire is out and that lake is going to be calling your name again at sunrise.  The night is really cool and you head inside to warm up the RV. You turn the thermostat and… nothing.  Don’t panic.  There are some simple things you can do to get your RV furnace running again.  Read on for simple, do-it-yourself tips for troubleshooting your furnace.


How does the furnace work?

There are several kinds of furnaces that may be installed in your RV, but most run in a similar way.  They’re powered by both electricity and propane and they force warm air out of the RV’s vents.  Before you try to fix what’s wrong, you should have a basic understanding of how your RV furnace works.

When you turn the dial on your thermostat, it sends a signal to the furnace’s control board, requesting heat.  The furnace’s blower begins to spin and draw air from the room over a heat exchanger and out of the ducts.  As the blower speeds up, the air closes the sail switch, which sends power to the control circuit board.  This lights the DSI igniter and heats up the furnace’s combustion chamber.  As the air passes over the heat exchanger, it warms up, passes through the ducts, and flows into the room.  Once the thermostat senses that the room is at the right temperature, the process stops.

If your furnace runs with a simple pilot light, it works similarly, except the furnace is controlled by the flow of gas.

But you’re still shivering, so obviously, something isn’t working.   Most fixes are simple, but when you’re looking forward to a miserable night, most people tend to forget a few basic things.

Things To Check When RV Furnace Doesn’t Ignite


The Gas Line

Is the gas on?  Try turning another gas-powered appliance in your RV on.  If that appliance also won’t work, you’ve found your problem.

Check the shut-off valve on the furnace.  Is it open and clear?  Is it damaged?  If you smell gas, get away from the RV and call for help immediately.

The Power Switch

No matter what kind of furnace you have, it has a power switch.  Make sure that it’s on! If it is, remember that your furnace needs electricity to run. Check the breaker to see if it’s been tripped.  If this is a frequent problem, you’ll need to call a professional to fix it.

The Thermostat

Is the thermostat set to a higher temperature than the room is currently at?

Does your thermostat have a programmable display?  If so, can you see an error code?

If you’re still not warming up, try turning the fan on.  This can force the furnace to start releasing heat. 

The Propane Supply

Your furnace also needs propane to run.  Check the furnace’s exhaust.  Can you faintly smell the gas?  If you can’t, you’re probably out of propane.  Be careful about replacing the propane itself.  If you’re not careful, you can burn yourself.  As always, if you sense a gas leak, leave the RV and immediately call for help.

It’s still not working!  What else can I do?

If you’re still not warming up, try these more advanced tricks.

The Air Filter

Has the air filter been replaced recently?  If your filter is dirty, the airflow moving through it is poor.  This heats your RV less efficiently and causes high utility bills that will make you think twice about renting that motorboat.  In addition, your air filter keeps the air clean, but it also keeps your heat exchanger from overheating.  If the heat exchanger overheats, the gas valve will close and the furnace itself will begin to overheat.  It will take safety measures to cool itself, then reignite.

Check the vents, registers, and filters.  Are they clogged?  Remember that you probably take your RV to places where mice, birds, leaves, and lots of other things can get stuck in the vents.  If you can, remove any blockages yourself, but a professional can help with trickier clogs.

People often ask if you can run your furnace without a filter and this is why you shouldn’t.  The furnace’s fan draws air from the room into the furnace.  That air goes through the filter before heating up and blowing back into the room.  Without a filter, the air passes through the filter trap, shooting fiberglass or other furnace trap materials into the room.  This is very unhealthy for you and bad for the environment.

The Battery

Electric RV furnaces need a 10.5-volt energy supply.  The easiest way to check this is with a multimeter tool, if you have one.  If you don’t have one, try connecting the blower to power.  The blower needs less power to run, so if it’s working, then you don’t have enough voltage to run your furnace and your battery needs to be changed.

The Furnace’s Fuse

If you have an electric RV furnace, check the fuse located between the board and its DC energy supply.  If you see black smoke, the fuse has blown and cut off your battery supply.

It worked!  Then it went out again!  Why is that happening and what can I do about it?

The Thermocouple

Furnaces with a pilot light have an element called a thermocouple.  The thermocouple is a safety precaution.  It tells you if the pilot light is lit or not.  If the pilot light goes out, the thermocouple closes the gas valve to prevent a gas leak. When your thermocouple isn’t working properly, it has trouble detecting the pilot light’s heat, which means it will occasionally close the gas valve because it doesn’t know the pilot light is still lit. If you’re handy, you can replace the thermocouple yourself.  If not, hire a professional.

The Thermostat

If your thermostat isn’t working properly it can send a signal to the furnace that it’s reached the right temperature when it really hasn’t. Try temporarily replacing it with an inexpensive model.  If the problem stops happening, you’ve found your issue and should probably replace it with a better model.

The Condensate Pan Drain

If your furnace has a condensate pan, its drain may be blocked.  The condensate pan collects the excess liquid that drips from the furnace.  If the drain is blocked, the pan can overflow and trip the safety sensor that prevents spillage.  The sensor will shut off the furnace, keeping you from a comfortable night’s rest.  Clear the clogged drain with a wire and make sure you’re emptying the pan regularly to keep this from happening again.

The Blower Motor

While the furnace is running, check the vent to see if hot air is blowing out of it.  To do this, put your hand over the supply register but be careful or you could burn yourself.  If you don’t feel hot air, it means the blower motor is out of power and the furnace has turned itself off to keep the heat exchanger from overheating.  The motor may also have a damaged fan relay or belt.  If so, you’ll have to call a professional to get these problems fixed.

A Word on Safety

First, to prevent many of these issues, it’s important to have a professional maintain your furnace regularly.  Most professionals recommend twice a year.

In the worst-case scenario, nothing works and you’ll have to spend a chilly night without a furnace.  People often ask if it’s safe to stay inside if the furnace is off and the answer is… maybe.  Every RV furnace leaks a harmless amount of carbon monoxide.  Carbon monoxide is a colorless, odorless gas that’s created when natural gas, propane, coal, wood, oil, or kerosene is only partially burned. When appliances aren’t working properly, they can leak an unhealthy amount of carbon monoxide.  People suffering from carbon monoxide poisoning commonly experience headaches, dizziness, nausea, or fatigue.  Occasionally, more severe carbon monoxide poisoning can cause disorientation, vomiting, loss of coordination, or unconsciousness.

Your RV furnace should not leak any more carbon monoxide than usual but it can draw this poisonous gas from other appliances and circulate it through the air in your RV.  It’s very important to install a carbon monoxide detector in both your home and RV.  You may not recognize the symptoms of carbon monoxide poisoning, but a carbon monoxide detector will alert you to danger before your symptoms become more severe.

To prevent carbon monoxide poisoning, injuries, and the occasional chilly night, it’s essential to hire a professional.  Although you can perform some minor fixes, they should install, repair, and regularly maintain your furnace.  If your furnace is malfunctioning often or severely, they will recommend that you replace the unit.  Although this can be expensive and frustrating, it’s also the safest measure for you and anyone staying in your RV.

Wrap Up

Hopefully, by now you’re warming up and looking forward to getting back outside again in the morning.  Get to bed and sleep well, knowing you’re in for a safe (and warm) night.

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