What Is An Onboard Propane Tank?
When we sold our travel trailer and bought a Class C RV we were surprised to see that the propane tank was permanently mounted underneath the RV instead of sitting in a compartment like in our trailer.
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Maybe it’s obvious to some but we had no idea that our motorhome would have an onboard propane tank, and we had some questions.
The long name for an onboard propane tank is ASME Permanent Horizontal Mount Propane Tank.
ASME is what any tank that has an internal pressure of more than 15 PSI is called. It’s permanent because it’s mounted to your RV and cannot be easily removed. And it’s installed horizontally instead of vertically like a more common DOT portable RV propane tanks.
Getting Propane For Onboard Propane Tanks
The biggest pro to onboard propane tanks is no more lugging around heavy tanks.
But the downside is you need to take your RV to the place you are going to refill it, which can be a pain for many reasons.
The first question I had when we first saw the onboard propane tank on our RV was “where are we going to fill this thing?”
It’s not a question with an obvious answer to people who are new to the world of permanent propane tanks but luckily it’s actually not as big of a deal as people might think.
It turns out that most propane refill businesses and stations have the ability to fill onboard horizontal propane tanks.
The biggest issue is just getting your RV close enough for the hose to reach.
Many of the places that offer propane refills have a long hose that can be used to reach the tank mounted to your RV.
If you know where the tank is it’s normally pretty easy to pull up next to the propane refill station and park with the tank right next to the pump.
Since our Class C only has a small 8 gallon tank we have to refill a lot when on the road.
We’ve refilled at gas stations, RV parks, bulk propane companies, and even businesses like Ace Hardware and U-Haul and so far every place has been able to refill our onboard tank.
The only place that hasn’t been able to help us was Tractor Supply Company.
I’m not sure if it was just that specific store that didn’t have a long hose, or if it’s all of them but they had to send us away with an empty propane tank.
They were really nice about it and directed us to a nearby business that could help us.
If you’ve been on the road and have been to places that don’t offer onboard propane tank refills please let us know in the comment section below. Maybe we can start a list of places that can’t refill permanent tanks to help out other campers.
To sum it all up, if your RV has an onboard propane tank the main thing you should be looking at is the area around the refill station.
If your RV is going to be too large to get close to the station you may need to find another place that has a more open area in front of the propane pump.
Things You Need To Do When Refilling An Onboard Propane Tank
There are a few things you need to do before refilling the permanent horizontal tank.
First, make sure all pilot lights are off inside your RV. You don’t want any flames to be going when refilling propane since fumes will be leaking around and inside your camper.
On that same note, make sure nobody is inside the RV when filling. It’s not only a fire safety precaution but it’s also a health hazard to be in an enclosed area around propane.
Some propane fumes will always leak into your RV when refilling, and you don’t want anyone inside, breathing in that dangerous gas.
The person refilling the propane tank is supposed to check both of these things before refilling, but it doesn’t always happen. The responsibility is mostly on the owner or operator of the RV.
Sometimes I also close the valve on the propane tank. The person refilling can also do this themselves, but I will do it if I have time just in case they forget.
Refilling A Permanent RV Propane Tank With A Portable One.
If you are parked somewhere permanently or long term moving your RV to refill the tank is a huge pain. Especially if your motorhome has a small tank like ours does.
We have to refill it at least once a month and when staying in an RV park for the winter it’s not fun to have to pack up the RV just to refill the tank.
One thing many motorhome and van owners do is add a tee to their permanent propane tanks so they can also connect a portable propane tank.
I recommend using the Sturgi-Stay Propane Adapter Kit (click to view on Amazon) made by M.B. Sturgis Inc (a well known propane accessory company).
This kit includes a high quality tee that has two quick connect propane connections on it, and a quick connect hose that will go between the portable propane tank and the quick connect on the tee.
The hose comes in different lengths depending on what kit you get.
Each outlet has its own on/off valve so you can open and close it directly from the adapter.
Since there are two quick connect connections on the adapter/tee you can use one connection for the portable tank and the other one for outdoor propane appliances like grills and propane fire pits.
Even if you aren’t planning on using a portable propane tank the tee is also a great way to add quick connections to your RV so you can use outdoor propane appliances.
This Sturgi-Stay Delux Propane Adapter Kit (click to view on Amazon) has all the things the kit linked to above has plus another quick connect propane hose for the second quick connect outlet.
The tee needs to be installed between the tank and the regulator.
Do not install the Tee after the regulator, this will put unregulated/high pressure gas into your RV’s propane system, which it’s not made to handle.
This could damage your RV’s propane appliances and gas lines, always install the Tee so the propane from the portable DOT tank can flow through the regulator before entering your RV.
Note that if you connect any external propane appliances to the tee you will need to make sure they have their own regulators since the propane supply is unregulated from the tee.
Most outdoor propane appliances have their own regulators but I thought I would mention it just in case.
Make sure the valve to the onboard tank is shut off when using the portable tank so the RV draws propane from the portable one and not the onboard one.
It’s a great way to make your propane supply portable and it can open up your propane refill options since many stores and gas stations offer propane tank swaps.
Frequently Asked Questions About Onboard/Permanent RV Propane Tanks
Do permanent propane tanks need to be re-certified?
Portable propane tanks need to be certified periodically to make sure they are safe for refilling and transport.
The person refilling the tank must always check the certification stamp or sticker to make sure the tank they are filling is up to code.
One interesting thing about onboard ASME tanks is they do not need to be re-certified. At least not right now.
Laws can change, but so far the USA doesn’t require RV onboard propane tanks to be re-certified, only portable ones need to be.
I think it’s a good idea to do a visual inspection of my propane tank before refilling anyways.
The tank on my motorhome is mounted onto the frame and is exposed to the road.
I like to check to make sure there are no dents or deep scratches on it. I also look for excessive rust just to be safe.
My motorhome is over 10 years old and the tank looks pretty good since the first owner didn’t drive it very often.
Have any more questions about filling permanent RV propane tanks? Leave a comment below.