Guide to Gas in your Motorhome or Bus Conversion

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Disclaimer – All gas work on a motorhome, caravan or bus conversion must be done to Australian standard AS/NZS5601 by a licenced gas installer. This is a guide to gas and a general information post only. Everything should be checked with your gas installer. The standard is often being revised, and incorrectly installed gas can be very dangerous.  

Most motor homes or bus conversions have some sort of gas appliances. Gas is a good alternative to electricity as it is cheap and gas bottles can go for weeks/months without replacing or refilling. There are a lot of rules and regulations when preparing for gas so we thought we would write a post with a few helpful things we have come across to help you when designing your bus conversion. This guide to gas post also includes our tips so you don’t struggle like we did! 

Gas bottle locations –  

It is very important that you read the regulations and rules in your state when you prepare for gas. There are rules where the gas bottles, and appliances can be located, and how they need to be installed.   

There are two options where you can mount your gas bottles. You can mount them externally, for example on a drawbar, or in a box inside the vehicle. If you decide to mount them inside the vehicle, the gas box cannot be accessed from inside the vehicle, only the outside. This is discussed further in the next point. 

In NSW, where we are, the gas bottles need to be at least 1.5 metres from any ignition source; for example, an oven. This is for safety purposes, in case of a gas leak. This 1.5 metres is measured from the ventilation hole in your gas box (refer to the ventilation section for more details about this).  

Gas bottle box requirements –  

Your gas box can be premade, or custom made depending on yours, and your gas certifiers preference.  

If you are going to make it yourself, it must be completely sealed from the inside of your vehicle and only accessible from the outside. This is in case of a gas leak, there is nowhere for the gas to vent inside your bus or motorhome, only outside.  

The gas box needs to have a hole for ventilation at the bottom, taking any gas that may escape down and out of your bus or motorhome. Alternatively, your gas box door may have a suitable ventilation source at the bottom. 

If you are going to make it yourself, your gas certifier may have other specific requirements; for example, check what they would like you to make it out of. We used 12mm plywood in our Toyota Coaster, however some installers may prefer metal or fibreglass.  

There are premade boxes available for purchase. Whilst these can be a little pricey, they save a lot of time and effort and you know they are completely sealed and should meet standard requirements.  

Some premade boxes –  

Caravan RV Camping 9kg Cyliner Box 

DIY RV Solutions make gas boxes for certain vehicles.

Restrictions for where appliances can be located –  

All appliances have to be installed as per the instructions for your units. Some appliances can only be installed in certain locations, and must not be below any opening windows, doors, or annex areas; for example a hot water system. If something like a hot water system is installed here, the window will need to be permanently sealed. This is so the gas doesn’t vent outside the bus or motorhome, and back in via the open window or door. 

Copper Pipe – 

Copper pipe should be located outside of the vehicle, with each appliance having its own branch pipe that enters the vehicle adjacent to the appliance. This pipe needs to be protected from damage; which can be covering it with a hose or pipe. 

Each appliance must have its own shut off valve that is readily accessible. 

There are a lot of rules surrounding the pipes, pipe length, joins and junctions. This is a guide to gas post only, and as this must be done by a certified gas installer we have kept it brief and leave this step up to the experts. If you would like to know more it is best that you speak to your installer or purchase a copy of AS/NZS5601.  

 Ventilation –  

Ventilation is extremely important if you will have gas appliances in your vehicle, for example a gas cooktop, oven or even some gas fridges. It is a requirement that you have two forms of ventilation in your vehicle; these vents need to be classed as ‘permanent’ and unrestricted. The two vents need to be at opposite ends of your motorhome with one at the top towards the roof (typically a skylight/hatch of some sort), and the other needs to be near the ground at the opposite end of the vehicle (generally a vent in the door).  

General –  

Prior to registration any connections will need to be completed by a licensed gas plumber, and a certificate provided for the work completed. You will also need a compliance plate attached to your bus or motorhome, which confirms it passes the regulations.   

If you are unsure of any rules or regulations where you are located, it is best to speak to a gas plumber or engineer directly. That way you can get the correct information.   

We found that a lot of gas plumbers were uncertain of the rules for motor homes or were unsure if they were able to do the job. There is a lot of information online and the instruction manuals are invaluable. Don’t lose them! Whenever our gas plumber was unsure, we turned to the manuals for help. There are specific gas plumbers who work on motorhomes and we have found these to be the most knowledgeable.  

It was also extremely helpful for us to talk to the engineer throughout the entire build. Not only did this build a working relationship where the engineer knew what stage we were up to, but it also ensured the problems, if any, were minimal. They know what they are doing, and what is required, so don’t be afraid to chat to them.   

Our Tips –

Book your gas plumber in advance!  

Our first, and most important tip is to book your gas plumber in advance.  

Gas plumbers who are able to work on motorhomes are few and far between, and get very busy!  

With our Toyota Coaster, we didn’t realise we were ready for a plumber until around a week before. There was an approximate 2 month wait list. We ended up calling around and finding another gas plumber who could squeeze us in around other jobs. This issue with this was the plumber was not well versed with motorhome standards and things took a little longer than they may have ordinarily.  

This time with our Mercedes Vario, we have booked well in advance. As we get closer to the date, if we do not believe ourselves to be ready we will reschedule. However it puts a little bit of pressure on the timeline, and will hopefully make us work a little harder!  

Cut any holes needed in your bus before you put your internal walls in!   

It may sound obvious, but cutting the holes for vents, and gas bottles beforehand is a step we skipped in our Toyota Coaster and 100% regret.   

 If the holes had been cut in the metal wall of the bus before we installed our internal ply walls, we would have had our gas box closer to the edge of the bus. Instead, we had to build a ‘make-shift’ aluminium surround between the hatch and the box to cover the approximate 10cm gap. So much more time, money and effort than we wanted!   

It also would have been so much easier to line everything up. Cutting one hole is easier than 2! As we had our ply wall already installed, we had to cut through both.   

Long story short, don’t wait until you have installed your internal walls! Plan it and cut the hatch space, or any other required holes first!    

Now that we have our Mercedes Vario, we have cut the holes prior to putting walls up, and also purchased a pre-fabricated gas box like the ones mentioned above. It took so much less time and effort!  

Try and have the gas plumber come in as early in your build as you can.   

By the time we got around to having a gas plumber come to do the work on our Toyota Coaster, we had already built a lot of the structures.   

This meant when trying to run the gas lines, we had to cut through our completed walls. It would have been much easier building the walls around them.    

When trying to connect our hot water system, the physical access was extremely difficult. We had not planned and left much working space around the unit. The plumber struggled to run the lines and organise the connections. And to top it off… he also kept hitting his head!   

Just a couple of tips when you prepare for gas, but definitely some good things to keep in mind.   

There is a great guide to gas on the Caravans Plus website for gas installations, so may also be worth a read.  

Now to actually build it….. good luck!