Revision History

This post has been updated based on experience from 2014 to 2017 – see “Hindsight” section below.

Why?

Soon after starting our caravaning adventures, we got a taste for free or cheap camp sites, not so much for the economics but for the relative peace and beauty of many of the sites around the country as compared to caravan parks. This meant learning to stretch the limited resources (water, toilet cassette, solar/battery amp hours, LPG tanks) in order to stretch the time spent off grid. A mid-winter trip to central Australia with four people in the van and annex emphasised the need for heating at night (despite daily temperatures in the high 20’s). When mains power was available, the reverse-cycle aircon in the van and an electric fan heater in the annex did the job. Off the grid, electric blankets fed from an inverter helped, but left the van battery under-voltage (and once flattened the vehicle battery when I had neglected to disconnect it). LPG is the available energy resource that travels and stores well. (Perhaps hydrogen fuel cells will overtake it soon?) With twin 9kg bottles on the van and refills available at van parks and country hardware stores, it seems that gas should be the last thing to run out. So an LPG heating solution made sense.

What?

We chose  the Truma Trumatic E 2400 LPG heater. It is designed for RVs by a company with a track record in diesel fired heaters for RVs. Operating on the heat exchange principle, it exhausts the combusted gases to the outside rather than into the van. Internal air is drawn in, passed through the heat exchanger and recirculated back into the van. This heater has four openings:

1. LPG;
2. inlet for air to be heated;
3. outlet for heated air;
4. combined exhaust gas outlet and external air (for combustion) inlet.

The last one combines two things into one using a coaxial arrangement, i.e. one is inside the other. This means there is only one external hole and one hose between it and the heater. Aside from reducing the number of holes and hoses, with this arrangement:

1. the outgoing exhaust gas  pre-heats the incoming air, improving the efficiency of combustion; and
2. the hotter hose is shielded from combustibles, fingers, etc. by the cooler hose.

This heater can be purchased in Australia for between $1,500 and $2,000. The best deal I have seen offered that includes installation was $1,650 for the heater and $600 for installation (mid 2014.) Tip: If buying online, beware of units that are not accompanied by Australian installation and certification documentation. The gas connection must be done by a gas plumber licenced for mobile installations. The remainder of the installation can be DIY but be aware that you need to be willing and able to:

• cut and later seal a 70mm diameter hole in your van’s wall,
• cut at least one 80mm diameter hole in a cupboard wall,
• do the 12 volt DC wiring and connection,
• securely mount a 5kg object in a vehicle that moves about.

Having done it ourselves, my opinion is that $600 is a very fair price for installation, especially given that the gas plumbing is likely to cost about half of that. Of course, the $600 offer referred to above was conditional on purchase of the heater from the same supplier: don’t expect to buy it for the best online price and then pay only $600 for someone else to install it!

Where?

Where in the van to install this heater was not obvious. Aside from the space, there are a number of safety and technical limitations. For example, the exhaust cannot be under a window or into an awning, you need a practical pathway for the gas plumbing, there are minimum and maximum lengths for the exhaust and the hot air hoses and there is a minimum separation between the hot air outlet and the cold air inlet. According to a local supplier and installer, under the bed is a popular location, with the exhaust hose going through the bottom bedside cupboard on the driver’s side. However our van has a side-opening boot under the head of the bed and below the side cupboards so (short of running the exhaust hose through the boot) that was not an option. We considered locating the heater under one of the bench seats, but the maximum distance to the outside for the exhaust hose (1 metre) was a problem as it would have had to wind around the HWS and/or the wheel wells.

Fortunately, on the driver’s side of our van, between the fridge and the back of one of the bench seats is a stack of three very narrow, very tall cupboards. Of all the cupboards, they are the least useful for storage because of their shape. We settled on re-purposing the top cupboard as home for the heater (and its two boxes of electronics), with the controller/thermostat on the outside of the same cupboard, just above the seat back. With gas already supplied to the (three way) fridge, the gas pipe for the heater could be tee-jointed into the fridge plumbing and brought up through the lower cupboards. Tip. Have your gas plumber to review your intended location and orientation before you commit yourself.  This may cost you a service call, but it is better than cutting a second hole in the wall of the van.

This heater can be mounted in a number of, but not all, possible orientations. Factors in choosing an orientation include: where the hoses need to go, their maximum length and, importantly if space is limited, their turning circle (radius of curvature). We ultimately choose the orientation with the exhaust port facing the van wall and the heat vent pointing upward. This was driven by the respective shapes of the heater and cupboard, and by the fact that the turning circle of the heat outlet hose was significantly worse than that of the exhaust hose and so it needed more space in which to make a right-angled bend. If you need a tighter right-angle in the hot air hose than can be achieved with the 80mm flexible hose supplied, have a look at the fittings in the Truma catalogue. As well as a fixed elbow, it shows fittings to suit installations with multiple hot air outlets. Tip. Don’t cut any holes until you are confident that your chosen location and orientation is going to fit. Put everything in place as much as possible, without cutting anything irreplaceable, to prove that your proposed location and orientation is doable. Remember that you need access to tighten screws and the plumber needs access to connect the pipe.

Hindsight (3 years later)

After several years use, we regret putting the hot air outlet so high in the van.  In very cold weather, with the heater on, we have measured a difference of many degrees between the air near the ceiling and the air near the floor.  This means overheated faces but cold feet!

The reasons for this include:

• hot air rises;
• the floor of a caravan is less insulated than the walls and roof;
• in wintry weather, the ground outside is wet and hence the air underneath the caravan is colder than the air to its sides and above.

Combined, these factors mean that the air near the floor needs heating more than the air near the ceiling. If we did it again, would put it the heater’s warm air outlet at floor level, and therefore mounting the heater as close to floor level as practical. Apparently, newer versions of this heater support multiple, distributed warm air outlets.  This seems like a good thing, but based on the above experience, we suggest that it should still be configured so that the majority of the warm air is expelled nearer to the floor than the ceiling. Unless the distribution system enables the flow from each outlet to be adjusted, this still means locating the heater near floor level.

How?

Depending on the orientation, the heater is fixed to its surrounds at either three or four points, using the supplied metal “L” or flat brackets. That does not seem like many mounting points for a 5kg object attached to the gas pipes in a moving vehicle; they need to be robust fixings, as does whatever they are fixed to. Our heater’s vertical orientation meant fixing it at one point underneath it, to the shelf and in two places on the side of it, to one cupboard wall. The gas fitting protruded below shelf level.  We made a replacement shelf from 13mm MDF to avoid cutting the original shelf and to give ourselves the option of starting over if we got it wrong.   To reinforce the cupboard wall, two lengths of 42x19mm dressed pine were screwed (using an excessive number of screws) to that wall. The side brackets of the heater were then fixed to the pine with hex-head timber screws. Tip. A small, cordless screwdriver is invaluable when fixing the heater into a cupboard not much bigger than the heater. We bought one especially for this job, but found it so useful that it has a permanent place in the van. It is much lighter than  a cordless drill, occupies less storage space and has surprisingly good torque. It came with right-angle and offset screwing attachments, which actually work very well.

The exhaust requires a 70mm diameter hole in the van wall. This is not the first hole we have cut in that wall, but is the largest (previous was 22mm for an Ezy Eye antenna cable inlet). The position of the hole depends on a number of things, including: location of the heater and interior pathways for the exhaust hose, the profile of the exterior van wall (ours is aluminium with a profile reminiscent of weatherboards) and, less visible but very important, anything inside the wall such as electrical cabling. If you are unsure about whether there is something in the wall, try calling the manufacturer’s customer service team. We have found Jayco to be very helpful in this respect. Given the chassis number they can refer to the layout diagram: whilst it may not include details of actual cabling, they know the principles of manufacture and can tell you which areas to stay away from.

The position of the hot air outlet also deserves some thought. The black, plastic vent supplied has fixed, slanted fins and rotates so that the air stream can be directed. Our outlet is close to the ceiling (see picture) so by directing it sideways or downward, the ceiling is not overheated. You might not want hot air streaming onto your face or body so that might help decide it. Unless you position the heater so that the hot air outlet is flush with the cupboard wall, you will need to use the hose supplied to channel the hot air. Whether or not you use the hose, a hole will be required in the cupboard wall.

Tip. Don’t cut the hoses to length or fix them to the walls until as late as possible. Cut the holes but leave the pipes overlength and loose in the holes. This gives you more wriggle room when positioning and fixing the heater. The cold air inlet can either draw air through a hose (similar to the hot air outlet), or from within the cupboard, in which case the cupboard must be sufficiently vented. We cut down a wooden, rectangular vent and installed it in the door of our heater cupboard (see previous picture). Good quality hole saws are expensive and this may be the only hole you ever cut of this size, so borrow if you can but make sure that it is sharp. Hole-saws drill a pilot hole before the larger hole: this will tell you whether you lined up the inside and outside positions correctly so be sure to check where it came out on the other side before going further. If you are less than one radius out, you get another chance! Tip: Sometimes it can make sense to drill the pilot hole from one side and then cut the larger hole from the other. It all depends on the materials involved, what determines the position of the hole and which side has more margin for error.

The controller/thermostat can be mounted flush, which requires a 50mm (?) diameter hole in the woodwork, or using the supplied casing, which requires a hole drilled for the cable. The cable supplied is ample in length: where you locate the controller/thermostat is limited by available pathways for routing the cable. We used the casing and put it on the outside of the heater cupboard because that was as good a position as anywhere else. Another advantage of the chosen location for the heater was its proximity to the battery management system, which is under the fridge, and hence to a 12VDC supply. Our unit has some spare, separately fused 12V connections available, of which I used one for the heater.

Results

It was late spring when we installed the heater and we have not yet had a winter in which to use it to its fullest. Our coldest morning in the van since installation of the heater was 12 degrees Celsius, so we took the opportunity to try it out. It took 40 minutes to raise the temperature to 22 degrees, which is encouraging.