How Many Watts Does an RV Furnace Use?

rv furnace watts LG

If you aren’t connected to shore power in your RV, knowing how many watts an appliance uses can be critical in gauging how long you can go before running out of power. So, how many watts does an RV furnace use?

Here’s what I know:

On average, an RV furnace uses between 37 to 150 watts per hour based on the BTU of the furnace. Typically small travel trailers and Class B RVs would be between 37-50 watts per hour, whereas Class C, A, and fifth-wheel RVs will be between 84 to 158 watts per hour.

In this article, we’ll explore whether RV furnaces run on electricity, how many amps an RV furnace fan draws, and what size of generator is required to run an RV furnace.

But we will also check out if RV furnaces run on 12-volt, and we’ll conclude by looking at whether RV furnaces can run without electricity and just on propane.

Let’s dive right in…

Do RV furnaces run on electricity?

RV furnaces use liquid propane to generate heat. But the igniter switch and blower use electricity to operate. So both are typically necessary to operate an RV furnace.

So if you’re boondocking you’ll want to use your generator or battery to handle the electric side of things to keep your RV’s heating system going.

And you can use a generator or battery power with an inverter to handle the electrical needs of your heating system. But, of course, none of this is an issue if you’re in a campground with full hook-ups.

But, how long can you dry camp in an RV? 

In a recent article of mine, I looked at the ideal number of days one could dry camp. In it, I explained what it means to dry camp, the difference between boondocking and dry camping, and how long the battery would last if you’re dry camping, including the 1 tip that can almost double your battery life!

Just click the link to read it on my site.

How many amps does an RV furnace fan draw?

On average, an RV furnace will use between 4 and 14 amps based on the BTU size of the furnace. Typically, small travel trailers and Class B RVs would be between 3 to 4 amps, whereas Class C, A, and fifth-wheel RVs will be between 7 to 13 amps.

But a typical RV furnace will draw 8 to 9 amps of power.

The draw depends on the furnace’s BTU (British Thermal Units) —- a measure of energy. Technically, it’s the amount of energy that is needed to increase the temperature of a pound of water by 1 degree F.

Naturally, a furnace with a BTU of 40,000 would require more energy than whose BTU is 30,000. But, there’s a subtle but vital point to note when it concerns how long a battery can run an RV furnace.

One should never use the battery till the whole power is drained! 

That would damage it. So, there’s the concept of Total Safe Battery Amp Hours. It’s very important to note because it’s a bit strange at first glance.

Let’s unpack it.

One should only use 50% of the power-generation capacity of Lead-Acid Batteries. In order to calculate the Total Safe Battery Amp Hours, you divide by 2. Say a furnace will draw 8 amps per hour, its safe hours are 4 hours (8/2).

So, you can only use it for 4 hours.

For Lithium Batteries, you can use 80%. So to calculate the safe hours, simply multiply the amp hours by 0.8. Say the amp hours are 10 hours. 10* 0.8 = 8. It can be used for 8 hours.

What size generator do I need to run my RV furnace?

A generator that is at least 4000 watts (often expressed as 4 kW) is the minimum size recommended for Class C, Class A, or fifth-wheel RVs, whereas a small trailer or Class B may be fine with a 2000 watt generator. But generators can go up to 12,000 watts.

Remember, a generator in your RV won’t just be powering the furnace.

So you want a generator that can keep the refrigerator on, and some of the lights and the furnace or AC. So a tiny generator, while it may be easier on your wallet, may not serve you well in the long run.

The electric stove, for example, is not always on. The AC is not always on. It’s likely the highest consumer of the energy being generated. The heater would not be used much in summer. But, it is wise to have a generator that has “excess wattage.”

So, the total wattage usage of all the appliances you’d be using in your rig is what should be considered.

Ideally, you want to have some “excess wattage.” Why? Some appliances such as your AC might use up to 2 to 3 times more wattage when it starts and when it’s turning off.

The bare minimum I’d suggest is a 4000 watts generator. Note that what’s vital is what we’ve explored above about your actual total wattage usage.

Do RV furnaces run on 12-volt?

RV furnaces run on 12 volts. It runs the blower of your furnace, which is what pushes the heated air from the propane heater into the RV. And it ignites the pilot light that heats the propane. 

As we found out earlier, the heat is actually being produced by the propane.

It’s the furnaces’ blower fans and the igniter that lights the propane that uses electricity. While the furnace’s fuel source is propane, these fans that are responsible for blowing the air around your rig run on 12-volt batteries.

Why Is Your Furnace Not Working?

You’re in luck because that’s exactly what I explored in a recent article of mine. I looked at issues such as why a camper could be blowing cold air and how RV furnaces work.

Just click the link to read it on my site.

Can an RV furnace run without electricity and just on propane?

An RV furnace needs an electricity source to power the igniter and the blower. That electricity source can come from shore power, a generator, or battery power.

RV furnaces, like other electric components, need electricity to function.

The electricity is needed to spark, become activated, generate heat, and then distribute the heat. They are akin to the furnaces or heaters in homes — they cannot function without electricity.

The sources of electricity may differ depending on the context.

As I mentioned, it could be from shore power, from generators, or batteries. But, an RV furnace cannot function without electricity.

Thinking of living in an RV full-time? Check out a recent article of mine where I shared 25 crucial pros and cons.

Just click the link to read it on my site.


In the article, we explored whether RV furnaces run on electricity and how many amps an RV furnace fan draws.

We found out what size of generator is required to run an RV furnace and if RV furnaces run on 12-volt. And we wrapped things up by looking at whether RV furnaces can run without electricity and just on propane.

Jeff Campbell

Jeff Campbell travels on and off with his 3 daughters in a Newmar Baystar Class A Motorhome. He writes extensively on both RVs, campgrounds, parenting on the road tips, remote learning & schooling, and much more!

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