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RV Propane Tanks: What to Know for Safety & Comfort

RV Propane Tanks: What to Know for Safety & Comfort

In today’s post, we’re addressing questions related to RV propane tanks.

With cooler temperatures heralding the coming of winter the season after fall, we’ve been focusing on various related topics, while at the same time trying to avoid being too blunt about the upcoming colder weather.

Today we’re addressing some additional common questions about propane, propane tanks, and propane safety in general.

Let’s do this before too much white stuff falls from the sky.

Important Propane-Related Topics

You may have noticed our series of recent propane-related posts. If you missed them, you may be interested in visiting them ahead of… well, you know.

You may also want to go back and take a look at these two posts:

With these specific propane-related posts laid out for your convenience, let’s get to the general questions that inspired today’s post.

Is There a Difference Between a BBQ Propane Tank and an RV Propane Tank?

Yes and no.

Some RVs use the same exact type of propane tank that a traditional barbeque grill uses, but some use a different type of tank.

You’ll recall from previous posts that there are a couple of different types of propane tanks used on RVs. One is a DOT propane cylinder (commonly associated with the BBQ grill) and the other is an ASME tank.

DOT Propane Cylinder

Some RVs, (especially smaller campers, travel trailers, truck campers, and 5th wheels), carry either one or two DOT propane cylinders.

This is the type of portable tank that you frequently see connected to a home BBQ grill.

Picture of DOT propane cylinder with an arrow illustrating where it sits on a travel trailer

DOT propane cylinders are carried on certain types of RVs like this travel trailer. Generally, you’ll see one or two cylinders under a tank cover as shown here.

DOT tanks are designed and governed by the standards of the Department of Transportation.

They’re made for portable applications and need to be replaced or recertified every 12 years (10 years in Canada).

ASME Tank

ASME tanks are made of somewhat thicker, heavier steel and are designed for more permanent applications. They may be permanently installed on an RV or outside a home or business.

The design and standards of ASME tanks are governed by the American Society of Mechanical Engineers, and while they don’t require periodic recertification, they should be inspected for rust, damage, and leaks on a regular basis.

 

 

Peter with the ASME propane tank built into our motorhome

Some RVs (like ours) have ASME propane tanks permanently built into the structure of the rig.

 

Peter with a large permanently installed ASME propane tank

This type of ASME propane tank is semi-permanently installed by a propane supplier at a stationary location such as a home or business (in this case, an RV park). Some RVers who are stationary for long periods may have access to ASME propane tanks like these which are both very large, and refilled as needed by a local propane retailer.

What Size Propane Tank Do I Need for an RV?

This really depends on how many propane appliances your RV has and how many units of heat each uses. It also depends on how you RV (snowbirding anyone?).

A BTU (British Thermal Unit) is a measurement of units of heat. By definition, a BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

The approximate energy provided by one gallon of propane is 90,000-100,000 BTUs.

So, if you have a 30,000 BTU furnace, it will burn about ⅓ of a gallon of propane running continuously for one hour, which equals about a gallon of propane every three hours.

A larger furnace will burn more, and a smaller furnace will burn less.

But you also need to consider what else you’re using propane for. The most common propane appliances in an RV are:

  • Furnace
  • Water heater
  • Refrigerator
  • Stove/cooktop
  • Oven
  • Portable propane heater
  • Generator

But again, some RVs have larger water heaters, refrigerators, and furnaces than others. Some RVs have only a stove while others have a stove and an oven.

So, the question of how large a propane tank (or how many DOT cylinders) you need for your RV is very much dependent on what appliances are run by propane and how much you use them.

How Long Does 20 Gallons of Propane Last in an RV?

Again, this depends on a number of variables including the BTUs of your appliances, the size of your RV, and the ambient temperature.

To generalize, though, you can gauge how long your 20-gallon propane tank will last by calculating your usage based on the fact that one gallon of propane generally lasts about 95 hours when used at a rate of 1,000 BTUs per hour.

So, if your RV has a furnace rated at 30,000 BTUs, then one gallon of propane should last about 3.17 hours.

If you have a 5-gallon cylinder of propane, you’ll be able to run your 30,000 BTU furnace for 15.85 hours. So, if you have a full 20-gallon propane tank, you can theoretically run it for at least 63.4 hours. Keep in mind that tanks can usually only be filled to 80% capacity, so take that into account when calculating.

We say “at least” because, in reality, your furnace would run longer than that simply because it won’t be on constantly. It cycles on and off as the space is heated and cooled.

However, (and this is a big “however”), you need to remember that it’s unlikely that the only propane-fueled appliance you’re using is your furnace. Your fridge may be sipping some propane, your water heater and stove may be used daily, etc.

A propane stove with three burners lit

When attempting to calculate your general propane usage, remember to include all of your propane-fueled appliances.

For further information on propane use, refer to our posts “How Much Propane Does an RV Furnace Use?“ and “How Much Propane Does an RV Fridge Use?

We also direct you to this “Propane Burn Time Calculator” which may be helpful in estimating how long your RV propane tank will last. The calculator allows you to enter the BTU rating of each propane appliance and the size of your tank to obtain the calculations.

Just remember to consider all of the variables as you estimate your propane needs.

If you’re wondering how much propane is left in your tank and you don’t have a gauge, check out our post and video on how to check the tank level without a gauge.

Can You Leave the Propane Tank On in an RV?

You can certainly leave the propane tank on/open when you’re parked and camping, using your propane appliances.

However, there are a couple of times when it’s best to turn your propane tank off.

The first is when your rig is stored. If you return home from a trip and don’t intend to use the RV for some time, you can turn your propane tank off since you won’t be using it. And you should definitely turn off your propane tank when your rig is in storage.

The reason for turning off your propane tanks when you’re not using the RV is that if you should develop a leak somewhere in the system, or if an appliance gets turned on accidentally, you wouldn’t know that there’s propane gas leaking. And this could create a serious explosion risk.

Another time you must turn off the propane is when the propane tank itself is being refilled. Although the person filling your tank for you will do that automatically.

All propane appliances should also be turned off during the filling of the propane tank so that no spark, flame, or other source of ignition is present. That’s also the reason that all propane appliances should also be turned off during the re-fueling of the RV itself.

The other time when it’s recommended to turn off your propane tank is when you’re driving.

We understand that people feel differently about this and there are many people who travel with their propane tanks on all the time.

However, in some states, there are laws regarding driving with your onboard propane tank on. Generally, these types of laws are related to tunnels.

For example, in Virginia, you need to stop to confirm that your tanks are off prior to driving your rig through a tunnel. In New York and New Jersey, you can’t drive through a tunnel or over some bridges with a propane tank open.

Can I Use a 100-Pound Propane Tank On My RV?

You absolutely can use a 100-pound propane tank on your RV. In fact, it’s done all the time.

Depending on the RV, of course, you could carry a 100-pound tank or a couple of 50-pound propane tanks connected by a pigtail.

However, you can also connect your RV to an external propane tank.

The following video shows how we connected to a large external propane tank when we were spending some time in a cold area in winter.

Why Are Propane Tanks Only Filled to 80%?

Like water, propane expands when it’s hot. However, its volume increases nearly 17 times more than water over the same temperature increase.

20% of the capacity of a propane container must be left empty to allow for this expansion.

This is why a propane tank can only be filled to 80%.

This is sometimes referred to as “the 80/20 fill rule” and it applies to all types of propane tanks, regardless of tank size.

Important Final Note Regarding RV Propane Safety

Every RV that uses propane or carries any type of propane tank must have a working propane detector. This is absolutely essential from a safety perspective.

Most RV propane detectors last from 5-7 years before they require replacement. However, it’s a good idea to replace your propane detector on a strict schedule so that you don’t forget and find yourself in a situation where it’s been 10 years since you’ve tended to yours.

Some propane detectors will beep in a regular pattern when they’re coming near the end of their effective lifetime. Never ignore this warning. It can be tempting to just disable the detector in an attempt to stop the beeping. But if you must do this to get through a night’s sleep, be sure to replace it at the soonest possible opportunity.

If your RV has a propane detector that’s hard-wired into the RV’s 12-volt electrical system, they’re very easy to replace on your own. We encourage you to check the date on yours today, and if it’s time to replace it, don’t wait.

Check your old propane detector for a similar replacement. It may look something like these:

Sale
Safe-T-Alert by MTI Industries 35-742-BL Dual LP/CO Alarm - 12V, 35 Series Flush Mount, Black
  • Double-Duty Alarm Detects Both Gas Leaks And Co Gas Simultaneously
  • Reliable 12V Power Means No Missing Or Dead Batteries To Replace. Operating Temperature: minus 40° F To plus 158° F
Sale
Safe T Alert 20-441-P-BL Mini Propane/LP Gas Alarm - 12V, 20 Series, Black
  • includes mounting bracket
  • power supply and current draw: 12 vdc 75ma @ 12 vdc

Another excellent piece of safety equipment to have onboard the RV is a combustible gas detector or “gas sniffer”. These are very helpful in quickly detecting gas leaks:

Combustible Gas Detector,Gas Detector Alarm, Portable Natural Gas Tester Detector/ Propane Methane Gas Sensor, Combustible Gas Sniffer with Sound Warning, Adjustable Sensitivity and Flex Probe
  • 1.High Senstivity Quick Respon: Highly sensitive (adjustable) with a quick reaction time, you will be able to detect gas leaks within 10 seconds and...
  • 2.Small Detector Super Sensor:A 14-inch flexible probe allows location and detection of leaks in hard-to-reach and confined spacesSix red LED's...

Remember – ignoring your propane detector can be an explosive mistake! Here’s a video showing how easy it can be to replace an RV propane detector:

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Craig Sandler

Monday 24th of October 2022

I have an onboard Propane tank built into my Dynamax Isata3. I live in it full-time now, but have to drive it to get the propane filled. Is there any way to hook up a 20 gal propane tank? Is there any other way to get propane w/o pulling up the stakes and driving to a propane station? Thank!

TheRVgeeks

Monday 24th of October 2022

Hi Craig. Yes, indeed there is a way. You need to get an "Extend-A-Stay" that gets added into the propane line between your onboard tank and the onboard regulator. That allows you to attach an external propane tank (that can be transported to be refilled). Check out this article: https://www.thervgeeks.com/rv-external-propane-connection/

Joseph Smith

Monday 24th of October 2022

So you travel with no food in your frig since the propane is off?

TheRVgeeks

Monday 24th of October 2022

Not at all! One feature of RV refrigerators is that they are extremely well insulated. You can easily leave them off overnight, or even for 24 hours, without much increase in temperature. It’s easy to leave them off while driving without having to empty the fridge.

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