RV Maintenance & Equipment

10 Furnace Questions New RVer’s Ask! (Answered For Beginners)

10 Furnace Questions New RVer Ask

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10 Furnace Questions New RVer’s Ask! (Answered For Beginners)

When it comes to RV appliances, RV furnaces generate a lot of questions. If your RV is equipped with a furnace then you’ll be able to enjoy your RV regardless of the season or outside temperatures. However, to get the most out of your furnace you’ll need to know the answers to some of these most common questions. Let’s go over some of those questions here.

10 Furnace Questions New RVer’s Ask! (Answered For Beginners) 1

Does My RV Furnace Have An Air Filter?

Probably not. Propane RV furnaces do not come from the factory with an air filter installed, or an easy way to install one. Since your RV furnace was designed to operate without an air filter, installing one can impede its performance and will likely void your furnace warranty. Even adding a wire mesh mud dauber protection screen over your exterior furnace vent will likely void your warranty.

10 Furnace Questions New RVer’s Ask! (Answered For Beginners) 2

Some RVs come equipped with heat pumps as part of the rooftop AC unit. These will have air filters that you’ll need to clean. On the interior side of the unit, you will usually see intake grates on either side of the unit. Those are typically held in with small tabs which allow you to remove the grates and access the filter material behind them.

Once you have that material out you can blow them out with compressed air, or gently wash them with cool water in your sink. If you get them wet, gently wring them or blow them out and allow them to dry before re-installing. You’ll need to clean these filters every few days during heavy use whether the system is running as a furnace or air conditioner.

Does My RV Furnace Have A Pilot Light?

Propane RV furnaces do have a pilot light, but it is ignited automatically by the electronics of the unit so you do not have to manually light it. Once the furnace detects the pilot is burning properly and the exhaust fan is running normally, then the main burner will be switched on and the furnace will begin generating heat.

Most RV furnaces will attempt to fire the pilot 3 times during a normal operating cycle. If the system fails to detect a normally burning pilot light in those three attempts, then the furnace will shut down automatically and wait to be serviced or reset.

If you hear your furnace going through this cycling procedure without it ever generating heat then check your propane supply for proper flow and pressure. If the propane system checks out then you’ll need to service your furnace unit.

Are RV Furnaces Standard Or High Efficiency?

Most RV furnaces are not considered high efficiency. US Government guidelines for gas-fired furnaces state that the furnace must be 95% efficient to receive an Energy Star rating in the US or Canada. Furnaces reaching 90% efficiency are considered “high efficiency” for the southern US states.

By contrast, a typical RV furnace is only about 60% efficient. The majority of the wasted energy escapes as heat through the exterior exhaust port. While this may seem like a lot of wasted energy, these furnaces are designed for maximum safety while operating in the rough and greatly variable environment that RVs see. They are also not designed to be used as a primary living heat source so efficiency isn’t a top concern for the furnace designers.

Can You Run Your RV Furnace When Sleeping?

It is generally considered safe to run your RV furnace while you sleep. In fact, if you don’t you can run the risk of waking up to frozen pipes or just being exceptionally uncomfortable while you try to sleep. RV furnaces include a long list of safety mechanisms that ensure they operate safely while you sleep. These include flame sensors and a sail switch which combine to confirm you have a proper flame, propane pressure, and free-flowing exhaust before the main furnace burners can ignite.

As with any furnace, it is important that you properly maintain and routinely check your furnace for optimal safety and efficiency. Always make sure your exhaust vents are unobstructed and that your gas system is free of leaks with a properly functioning regulator. When working properly, your RV furnace is safe to operate day or night.

Can You Run Your RV Furnace While Driving?

You can travel with the furnace on with some caveats. There are some state and federal laws that disallow travel in an RV with your propane tanks turned on. For example, the entire State of New York forbids any travel on public roads with your propane valves open.

There are also federal regulations regarding passage through tunnels with open propane tanks. Finally, there are some commonsense situations where having an open flame would be a bad idea, like while filling up at the gas station. Baring these situations, you can travel with your furnace operating.

Can The Heat From Your RV Furnace Melt The Furnace Vent?

The heat from the furnace should not be hot enough to melt interior furnace vents. The air coming from the interior vents is heated as it passes through a heat exchanger over the main burner. Since that air is never in direct contact with the flame, it won’t get hot enough to melt plastic vents.

The exterior vent is a different story. That air does come in direct contact with the flame and it can be quite hot. This is why the exterior vent is a specially designed metal unit. If you ever need to replace that vent always do so with an original replacement part from the specific furnace manufacturer.

How Hot Does An RV Furnace Get?

This depends on where you are measuring the temperature. Propane burns at around 3600 degrees Fahrenheit and exhaust gases escaping from the vent can easily exceed a few hundred degrees Fahrenheit. The constant cycling of cool outside air in the combustion chamber keeps the furnace unit itself relatively cool.

The furnace also includes some insulation and heat shielding to keep the exterior temperature from reaching exceedingly high temperatures. The interior of the heat exchanger for example should be in the 140 – 180 degree Fahrenheit range. The exterior surfaces of the furnace unit should be significantly below that.

The air temperature at the different registers throughout the RV will vary depending on a number of factors. Distance from the furnace, how well your RV is insulated, where the ducting is routed, etc. will all play a role. Even the closest furnace vents should blow warm, not scalding hot air. You should easily be able to hold a bare hand over any interior vent in your RV while the furnace is operating normally.

Are Digital Thermostats Better Than Analog In An RV?

Digital thermostats are generally considered better than their analog counterparts for a number of reasons. Digital thermostats allow you to set a specific temperature to control your furnace and/or air conditioning unit. They will also operate your furnace more efficiently since they rely on algorithms to cycle your furnace at optimal rates.

Some can even learn over time how your environment reacts to the cycling of the furnace. This allows the thermostat to optimize and adapt to your specific settings. Finally, most digital thermostats are programmable which will allow you to preset your furnace operation to specific times and days of the week. This can greatly cut down on propane use in your RV.

On the downside, digital thermostats are more expensive upfront but they will generally pay for themselves over time. They also usually require batteries to power them which can fail and leave you without heat.

Analog thermostats have their benefits as well. They are cheap, reliable, readily available, easy to install or replace, and don’t require extra batteries or special power to operate. For most RVers, these benefits are superseded by the benefits offered by digital thermostats.

Do They Make In-floor Heat For RVs?

Many modern RVs have sealed underbellies that contain furnace ducting that runs under the floors. The heat running through that ductwork will warm the space between the belly pan and the floors of the RV.

While this is not intended to heat the RV through floor radiance, it does do a great job keeping the floors from feeling too cold when you walk on them in socks or bare feet. It also does a great job keeping other RV systems that are located in that same belly space like plumbing and the fresh water and waste tanks from freezing.

How Long Will A Battery Run Your RV Furnace?

The amount of time your furnace will run on your battery will vary greatly depending on a number of factors including:

1.) Size of your batteries – More amp hours provide longer run times.

2.) Age and condition of your batteries – Old or worn-out batteries will decrease run time.

3.) Location of your batteries – Cold batteries will decrease run time.

4.) How frequently your furnace runs. Furnaces will only run constantly if they can’t keep up with their heating duties. This can occur if the furnace is too small for the RV, it is unusually cold outside, or there is some other factor (an open window, door vent) preventing the interior from properly warming. Normal operation will be the furnace turns on, and runs until it heats up the interior to the set temperature. It will then turn off until the interior temperature drops to a set temperature, then the cycle will repeat. The colder it is outside, the longer and more frequently the furnace will run and the shorter the time the battery will last.

5.) The amount of power your specific furnace draws. The power used by the furnace will be related to its BTU output. While higher BTU ratings are directly linked to burning more propane, the higher outputs will require bigger fans to move the air which will increase the electrical usage of the unit as well. The smallest furnaces in popups and small travel trailers will use less than 5 amps, while furnaces in large 5th wheels travel trailers and motorhomes can pull upwards of 15 amps during peak operation. The higher the amp draw, the shorter the battery life.

To figure out roughly how long your furnace will last you’ll need to know two things and guess at one. The two things you’ll need to know are your battery bank amp-hour rating and the running current draw of your specific furnace which can be found in your owner’s manual.

Using those two numbers you can calculate how long the furnace will run if it were to run constantly. For example, if your furnace draws 5 amps and you have a 100 amp hour battery then you can expect to get 10 hours of run time out of it.

Remember that you shouldn’t drain your batteries beyond 50% so a 100 amp hour battery really has 50 amp-hours of energy that can be drained before you start to damage the battery. So, you have 50 amp*hours/5 amps = 10 hours. From there you can make adjustments based on your expected run time and run frequency.

If you say the furnace will run 15 minutes twice an hour then it’s running at 50% and you can expect to get 20 hours out of your battery. This also assumes that there are no other draws on your battery, which there likely will be. To get actual battery life you would have to add up all the draws on the battery together to calculate the actual battery life in your RV.

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