What's it all about?

At home we don't really think much about power sources and capacities - it's all there 'on tap'.  In our motorhomes things are rather different, we need a portable and reliable heat source source and while you can 'have a hook-up' to mains electricity on site, that may not always be convenient.  Vehicles normally rely on 12 volt batteries for mobile power but this just isn't powerful enough for heating.  For example if you used your battery to run a small 1kW fire for space heating or the same power ring for cooking it would take 85 amps from your leisure battery which would then last only about half an hour before needing a major recharge!

The answer for most of us is bottled gas - also known as Liquid Petroleum Gas, LPG, Butane and Propane or sometimes as 'Calor Gas', this being the name of the brand leader.  It's convenient and very powerful and since it's stored under pressure as a liquid you get lots of it in a very small space - so it has become the fuel of choice for most motorcaravanners.  The container is a strong steel bottle, and some portable sizes contain enough gas for several weeks use.  The bottles are readily available at home and abroad, in various sizes - usually described in Kg.  A gas bottle is normally hired from the gas supplier for a once-only payment though increasingly suppliers will lend you a bottle for free. The gas contents are charged separately. When a bottle is empty it is simply exchanged for a full one, for the price of the gas only.  Unfortunately there is no standardisation of LPG bottles across Europe.

Refillable cylinders and fixed tanks are becoming much more popular in part to get round the European problem but also because they are so much more convenient - no lugging heavy bottles around, no searching for the right kind of bottle and the great advantage of being able to top-up whenever you want, just as you do with other fuels. It's a whole new way of thinking about gas management - bliss! 
Click here for a FAQ on refillables or click here to go to our Gaslow pages (both new window).

By the way the term bottle and cylinder are interchangeable here for removable containers. A 'tank' on the other hand implies a fixed unit.

The bottles must be used in an upright position to take off vapour from the top of the bottle and not liquid which would be dangerous for 'habitation' use. A 'regulator' is also required to control and stabilise the gas pressure throughout the life of the fill and to compensate for temperature changes. The regulators are different for the different gases and the fixings are different too so no mix-ups can occur.  Most newer vehicles have gas fittings and appliances designed to a new standard where a single 'universal' regulator is fixed to the vehicle and the bottles are connected to that by high pressure 'pigtails'.  The bottle and/or regulator will be fitted with a main on-off valve.  It is sensible to carry two bottles to avoid running out - which always occurs at a most inconvenient time - like the middle of the night!  Most 'vans have built-in ventilated gas storage lockers with room for two bottles though not always very large ones.  We use twin bottles in our Hymer and at home where we use LPG as fuel for our domestic gas hob.

Sometimes purpose-made LPG tanks are used instead of portable bottles. These are built-in to the vehicle and are refilled at special filling stations in a similar way to the vehicle's fuel tank. These tanks usually hold much more gas than a portable bottle, are very strongly made to withstand the pressure and so are relatively large and very heavy.  One advantage is that they are easier to fill in various countries abroad, though some countries have very few outlets.  With the increasing availability of LPG at petrol stations dedicated tanks are becoming more popular but remember that there can be a significant effect on available payload. The other issue is that fixed tanks are banned from some tunnels including the channel tunnel.

The interesting hybrid is the refillable bottle like the Gaslow unit, we've had two fitted to our Hymer complete with a 'remote' external filler and I must say they do seem to offer something of the best of both worlds albeit at considerably greater initial expense than a free loan bottle!  The extra convenience both at home and abroad is most welcome though and once installed the per Kilo/Litre running costs are much lower.

Which Gas do I need?

There are many good gas supply companies, but for use on the move the best choice is one which distributes nationwide, especially if you can only use the smaller bottles. Calor is the market leader and the company supplies both Butane and Propane.  Butane, usually in blue bottles, is heavier than Propane, and more energy can be stored in a given bottle size. Propane, although lighter than Butane, has the advantage of remaining usable under freezing conditions and is therefore the best choice for all-season motorcaravanning.  Butane stops working as the temperature falls towards 0° C and it can reach this very quickly because it is self-cooling as it evaporates in use. In contrast Propane works well at very low temperatures indeed. Since Propane also works OK at normal temperatures many motorcaravanners like us use Propane all year round.

Note that gas bottles cool themselves as gas is consumed so butane can be problematical even on cool mornings.  When gas is delivered by opening a valve the bottle pressure is reduced and some of the the liquid vaporises, consuming heat in the process, the only heat available is in the liquid so the liquid temperature will necessarily fall.  As gas is being consumed the liquid in the gas bottle will get colder than its surroundings and when the air temperature approaches freezing point, the liquid gas can become so cold that it cannot vaporise.  Propane will be OK right down to about minus 40° C and very few of us camp in temperatures like that!  At low temperatures and high gas consumption you might see frost forming on the outside of the bottle, a useful indication of gas level. If a Butane bottle starts to die in low temperatures, gas flow may be improved by warming the bottle but only with safe heat like a container of hot water standing beside the bottle.

Being different gases, butane and propane have to be bottled at very different pressures, and traditionally they have each required their own unique regulator to suit the pressures required by the appliances. In the UK the pressures were 28mbar for butane and 37mbar for propane. Newer, post 2004, and many imported vehicles use a common 30 mbar for either gas and some older German motorhomes have a 50mbar system. Note that you cannot pick and choose from these standards, you must use the one your appliances were designed for. The regulators for different gases cannot easily be mixed up, since each has a different fitting.  These fittings were not standardised throughout Europe but the new 2004 standard goes a long way towards harmonising them.  In the UK the range of bottle sizes offered by companies such as Calor covers virtually all needs. There is also an international company called Camping Gaz, who supply smaller sizes than Calor, suitable for some smaller motorcaravans and general camping. Their bottles are available all over Western Europe except Scandinavia but contain mostly Butane for summer use.

Calor offer three bottle sizes holding; Butane (blue), 4.5kg, 7kg and 15kg and Propane (red), 3.9, 6, or 13kg. Some suppliers like FloGas also do a slightly smaller 11Kg Propane which can be very useful in some gas cupboards, especially imports, being only 305 mm dia. The largest Camping Gaz bottle holds 2.72kg of Butane.  Gaz also comes in smaller sizes still but is very expensive to buy compared with the larger UK bottles.  In addition to capacity all these bottles deliver gas at different rates - it can be impossible to run all appliances simultaneously from the smaller bottles but is no problem with the larger ones (see table). Incidentally some suppliers will exchange any of their own bottles for others of different sizes as required.  We have a long list of the many Flogas brands - if needed please email us.

How much will I need?

Gas can supply virtually all of the heat energy needs of a motorhome - hot water for washing and showering, washing up, cooking, heating and refrigeration - possibly even air conditioning. Most of these needs could be satisfied or supplemented by a mains hook-up if available, or even by the site facilities in which case the gas consumption could be very low indeed, albeit with some personal inconvenience.  We are quite fortunate in being able to just get two 11Kg Propane bottles in our gas cupboard, so with 22 Kg (~46L) available we don't have to change bottles very often and could at a pinch go for six weeks or more without needing gas.

As an example, we spent 21 nights away in indifferent weather during March April & May and used just one 11Kg bottle - about 1/2 Kg per day.  We have a 2 burner hob, Truma fire/blown air and water heating system and refrigerator, there are only two of us but we very rarely use mains or any site facilities.  We are all different of course, others have reported consumption of about 2/3 Kg per day in summer but at least these figures will give you a guide.  Surprisingly many people use more gas in summer than winter due to running a fridge flat out in summer and using hook-ups in winter!.

Is it safe?

There are several safety regulations and features for LPG use.  Our own responsibilities include turning off all bottles when travelling* and when on ferries or in tunnels as well as ensuring that the system is installed by and regularly inspected by qualified people.  Less obviously you mustn't store things like batteries in the same cupboard due to the spark risk and the rubber connection hoses should also be replaced at least once every five years.  * There is a new safety device called Secumotion that can be used while travelling.

Modern appliances have flame failure devices built in, so if there's no heat the gas shuts off automatically. This is why you have to press and hold the gas tap to light the burner - to give the thermocouple device time to warm up.  Releasing the tap early and seeing the flame go out is a simple test that the flame failure device is still working!  Possible leaks in the gas system are made obvious by adding an obnoxious smell to the gas, so if you do get a leak - you will know!  Any leaked gas must of course be able to escape from the 'van and since LPG vapour is heavier than air you will normally see floor vents in your gas locker and possibly under appliances too, probably complete with anti-mouse netting. These holes must not be covered even accidentally.

How do I know when it will run out?

With only a finite amount of gas in a bottle and no on-tap supply we have to try to keep an eye on the shrinking contents of the bottle, and also try to have a quick and simple way to change to a new bottle as soon as possible after the first one becomes empty. One thing you should never do with gas is run out! To wake up in the morning and find that the fridge has been off for hours is not good news.  Having decided to carry two bottles it is important to have a suitable change over device too.

Various units are available to enable both bottles to be connected to the 'van's input, through a manual or automatic change-over valve. Although not traditionally fitted in the UK automatic change-overs offer great benefits and are now becoming increasingly popular. Wrestling with a change over system in an external gas cupboard at 6 am on a cold rainy night is no fun at all!!  Automatic valves need no action to achieve a 'seamless' change-over, but there is of course a need to keep an eye on them in case you finish up with two empty bottles.  Our German Triomatic system (illustrated) has an auto-changeover with a pressure valve to indicate which bottle is in use and roughly how much gas is left.  Other pressure sensing devices like the Gaslow gauge will show a pressure drop if the user watches it regularly. This unit is fitted into the gas line or onto each regulator and also serves as a gas leak detector since with all appliances turned off, including the bottle, the pressure trapped in the gas system should not drop. Such gauges are not 100% accurate but will certainly indicate 1/4 maybe 1/8th bottle clearly enough. The Gaslow auto-head has clear indicators to show when a bottle empties and their latest refillable cylinders have built-in float gauges accurately showing the level from 50% down to 18% remaining.

And Finally, how about going abroad?

Gas bottle fittings are not standardised throughout Europe and the Calor company do not operate on the Continent, so it is necessary to carry enough gas to see you through, possibly relying more on hook-ups; or you could emulate the locals, and obtain a suitable bottle and regulator over there. One useful bottle, offering 5-6 Kg of gas with a larger 11-13 kg option can be found all over Germany, Austria and Switzerland.  You would only need to purchase one bottle and regulator and by using the Continental bottle all the time, with the Calor one only to bridge the short gap while replacing the empty one, a tour in this area could last indefinitely!  

The increasing use of user-refillable bottles from Gaslow and MTH and also separate gas tanks is largely driven by the extra convenience when touring Europe, with a couple of adaptors you can top up whenever is convenient at any Autogas point or filling station and there are thousands across most of the continent.

Also available abroad is the little Camping Gaz 2.72 Butane. This is a handy 'last ditch' reserve, and is ideal for a gas barbecue as well.  Gaz adaptors are available here for UK regulators and it might be wise to carry one just in case!  Imported European 'vans usually come with euro-fittings as standard, sometimes it's easier to keep those and use adaptors for UK bottles, that way you may have easy use abroad too! 

The new style 30Mbar remote regulators are fitted to the vehicle itself with 'pigtails' connecting to the bottles. As a result it should now be possible to simply carry spare pigtails to connect to 'strange' foreign bottles! 

Some propane gas & bottle data kindly supplied by Calor Gas

Note how the bigger bottle can deliver gas at about twice the rate of the smallest!

Cylinder	Dim dia x ht mm	Typ gross wt	Max gross wt	Rec offtake 20/1°C
3.9 Kg	246 x 345	10.3 Kg	10.7 Kg	0.28 m3/h (7.5 kW)
6.0 Kg	246 x 490	15.0 Kg	15.5 Kg	0.42 m3/h (11 kW)
13 Kg	318 x 585 (605 max)	32.0 Kg	40.0 Kg (!)	0.57 m3/h (15kW) *
			* i.e. twice the output of a 3.9 Kg bottle.
11 Kg Flogas	305 x 550	24 Kg
11Kg Gaslow	305 x 540	23Kg approx