Caravan Gas: The Ultimate Guide (with costs)
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Words by Rod Farrendon
There are two sources of stored energy carried in our caravans: one is 12V electricity, usually stored in heavy, lead-acid leisure batteries, while the other is, of course, LPG. This is also generally stored in rather heavy bottles/cylinders.
Combine the weight of, say two full 6kg propane cylinders with a good-quality, 110Ah leisure battery and you’ll reach a figure of around 60 kg or 9½ stone – phew! However, for our modern day ‘palaces on wheels’ they’re a necessity.
With a 12V supply, and gas in the tank, we want for nothing in our home from home we’re ‘cooking on gas’, so to speak.
In the past, even the lighting was gas powered (although it was hot and dangerous, especially with small fingers about). Today we can rely on bottled gas power for almost everything:
- The fridge runs much more efficiently on gas.
- The heating does, too. With a bit of 12V juice for the pump or fan, you are toasty far quicker with gas heating, than on 230V mains.
- Most of us use the gas cooker, even when on EHU. Thank goodness there are still at least three gas rings on the hob (our microwave always becomes a cupboard!).
- Shower time is gas-powered, too, and there’s no problem creating much lovely, piping hot water. Again it’s more efficient (don’t forget to remove the boiler exhaust cover, if you have one).
Gas is one of the greenest fossil fuels we use, so, if you combine it with a solar panel to charge the 12V leisure battery, you can enjoy one of the greenest, most comfortable, adventurous (or chilled out) holidays there is.
Here is a closer look at this versatile fuel, and how it is used as caravan gas.
Liquid Petroleum Gas
LPG is a by-product of the oil-refining industry. Burnt off, and considered a nuisance when first discovered, it took a while to realise its potential as a valuable energy source in its own right.
LPG is a viable, transportable fuel. You can keep the gas as a liquid in a pressurised container, which means you can store a lot of energy in a small space.
It’s highly flammable, odourless (the smell is added), non-toxic and, being heavier than air, will settle in low spots (hence the floor vents in caravans, known as gas drop-out vents).
The two main dangers, should a leak occur, are fire and explosion, and from asphyxiation.
LPG can displace air. In an enclosed and unvented space, an unknown leak could create a dangerous environment. Therefore, don't store a gas cylinder in a sealed awning or pup tent.
People or pets sleeping near the ground would be in danger of asphyxiation from a leaking gas cylinder and, of course, fire/explosion if it ignited.
If you don’t have room in the caravan locker that’s designed for gas storage, leave the bottle outside. Any leakage will disperse into the atmosphere.
Caravan gas: butane v propane
In the UK, LPG is either propane or butane. So, which gas is best for caravanning? Which gas is cheapest? Which burns hottest?
I’m not going to put my finger in either of their flames to find out the hottest. In fact, they burn at about the same temperature.
To describe the difference, without getting into megajoules and some serious science, I’d explain it like this: less butane is needed, compared to propane, to produce the same amount of heat.
One litre of butane will last 12% longer than one litre of propane. The biggest difference, and probably the most important difference to caravanners, is the boiling-temperature range.
This is the temperature at which LPG will still vaporise and turn from liquid to gas.
Butane gasses at temperatures down to minus 2°C, while propane gasses as low as minus 42°C!
This means propane is the best choice in colder weather. You’d have to caravan to Siberia, before you had any problems with propane.
Butane v propane costs
I made a cost comparison by converting kg to litres. Propane is 1.96 liquid litres per 1 kg, while butane is 1.72 liquid litres per 1 kg. Using the online shop of one of the leading UK suppliers of bottled gas prices, 6 kg of rental propane works out at £1.99 per litre, and 7 kg of rental butane at £2.15 per litre.
That’s a difference of around 8% between them. A litre of butane creates 12% more heat. The cost difference is a few pence per litre in butane’s favour.
Autogas can be butane or propane, or a mix of the two. In the UK, it is propane. At this time, the average price at the pumps per litre is £0.64.
As I mostly camp off-grid, a plentiful supply of gas is essential: for heating, hot water and chilling the Pinot! Finding the right balance of cost of gas, availability, cost of set-up, weight, etc, is a question requiring some serious thought.
A big problem that still exists in the world of LPG is the illegal filling of rental gas cylinders at Autogas pumps using adapters bought on the internet and guesswork!
Not only is this practice extremely dangerous, it’s illegal. It also makes it difficult for those that use legitimate and safe refillable cylinders when attendants have been instructed to stop anyone from filling gas cylinders at the pump.
There are no safeguards built into rental cylinders, and they remain the property of the supplying company.
Calor is the caravan fraternity’s most widely-used and easily-available bottled gas in the UK. You are never far from a Calor gas retailer, which certainly gives us peace of mind. Calor brought us the revolutionary Calor Lite bottle in 2007, helping keep noseweights down.
However, a recall in 2014, over possible degradation of the cylinders, has limited supplies right up to the present day. Existing 6 kg CalorLite users can exchange their cylinder for a standard 6 kg cylinder, or 3.9 kg cylinder, which normally weighs less than a ‘6 kg Lite’ when both are full.
- Calor Lite (limited supply) 6 kg @ £26.45 = £2.26 per litre, gross weight approx 10.5 kg.
- Calor Propane 6 kg @ £23.45 = £2.00 per litre, gross weight approx 15 kg.
Flogas is also a big player in the UK bottled-gas market (it acquired BP LPG in 2013, and has picked up the ‘lightweight gauntlet’. Since 2014, it has produced a lightweight, see-through, GRP propane cylinder, similar to the Safefill design.
This is good news for those of us who want a lightweight gas cylinder. Retailers are not as widespread as Calor, but they can usually be found not too far away, typically on industrial estates where the likes of tool hire companies often keep a stock.
Gas light cylinders use a 27mm clip-on connection. Adapters from clip-on to threaded connection can be bought for around £7.50. If you would like to change the complete hose to one with a clip-on connector end, it costs about £30.
- Flogas Gas light 5 kg @ £23.00 = £2.35 per litre, gross weight 8.7 kg.
- Flogas Propane 6 kg @ £23.25 = £1.99 per litre, gross weight 14 kg.
How to pay 5% VAT on caravan gas!
If you can find a domestic gas supplier to refill your cylinders, you can legally purchase gas with only 5% VAT charged, instead of the 20% VAT you have to pay on Autogas.
Safefill launched its direct-fill (you fill straight from an LPG pump at a fuel station, for example), lightweight, glass-fibre, see-through range in 2011.
These are not rental cylinders. Instead, the user buys and owns the system. Again, there is good news for those who require a lightweight cylinder combined with cheaper gas.
- A 7.5 kg cylinder costs £159 + £14 postage
They have several safety features, including: overfill protection (all gas cylinders should only be filled to 80%, to allow for expansion); a check valve that stops accidental gas release, and a pressure release valve. They meet ISO standards.
While these cylinders can be legally filled at LPG pumps at a petrol station, they do need a gas safety check at 10-years old. The check ensures the safety features are replaced and continue to be reliable. Safefill doesn't need specialist installation.
- Safefill 7.5 kg fill-up @ £9.40 = £0.64 per litre, gross weight 11.6 kg
Gaslow is a name that’s been around for a few years. It’s mainly known for its custom-fitted, self-refillable gas systems in motorhomes and caravans.
Gaslow manufactures a direct-fill, steel cylinder. It is not see-through, but it has a gauge and is built to the R67 automotive standard for ‘tanks mounted in a vehicle propelled by LPG’.
Gaslow bottles have a single handle for lifting (I'd prefer two); that said, it's great to see another good-quality, refillable cylinder on the market. They, too, need a safety check every 10 years.
- Gaslow single-cylinder refillable system £341.50 + £7.80 + fitting (est £100, not a DIY job).
- Gaslow direct-fill 6 kg cylinder £164 + £7.80 p&p
- Gaslow 6 kg fill-up @ £7.52 = £0.64 per litre, gross weight 14.15 kg
How much does caravan gas cost?
Some manufacturers, but not all, give approx capacity figures in litres. So, to provide a level playing field, I have based my calculations on a recognised formula of 1.96 litres of propane liquid gas per 1 kg of weight.
Using a high-usage figure of 5 kg per week, and a low-usage figure of 1 kg per week (a caravanner on EHU), here are the average costs from rental-cylinder suppliers and direct fill-cylinder suppliers. I’ll base it on 10 weeks usage.
- 10 weeks @ 5 kg p/w = 50 kg or 98 litres,
- 10 weeks @ 1 kg p/w = 10 kg or 19.6 litres
Cost of bottle/system purchase and the first 10 weeks…
- Calor high usage – cylinder rental £39.99 + 98 litres @ £1.99 = £235.01.
- Calor low usage – Cylinder rental £39.99 + 19.6 litres @ £1.99 = £78.99.
- Flogas high usage – cylinder rental £30.62 + 98 litres @ £1.99 = £225.64.
- Flogas low usage – cylinder rental £30.62 + 19.6 litres @ £1.99 = £69.62 .
Gaslow high usage – system purchase £662 (twin cylinders and regulator, etc) + fitting (est) £100 + 98 litres @ £0.64 = £824.72.
Gaslow low usage – system purchase £662 (twin cylinders and regulator, etc) + fitting (est) £100 + 19.6 litres @ £0.64 = £774.54.
- Safefill high usage – cylinder purchase £159.00 .+ 98 litres @ £0.64 = £221.22.
- Safefill low usage – cylinder purchase £159.00. + 19.6 litres @ £0.64 = £171.54.
The next 10 weeks…
- Calor high usage 98 litres @ £1.99 = £195.02.
- Calor low usage 19.6 litres @ £1.99 = £39.00
- Flogas high 98 litres @ £1.99 = £195.02.
- Flogas low19.6 litres @ £1.99 = £39.04.
- Gaslow high 98 litres @ £0.64 = £62.72.
- Gaslow low 19.6 litres @ £0.64 = £12.54.
- Safefill high 98 litres @ £0.64 = £62.72.
- Safefill low 19.6 litres @ £0.64 = £12.54.
Using Autogas Abroad
LPG in warmer foreign countries has a different composition to UK LPG (90-100% propane), and this ‘blend’ can vary depending on the time of year. In Spain, the mix is typically 65% butane and 35% propane (mylpg.eu). Butane has an extra carbon atom, which gives it a higher energy value and a slightly ‘dirtier burn’ than propane.
This means that regular travellers to warmer countries should have their Thetford and Dometic fridges serviced annually. The clean will remove soot (carbon) from the flue and, possibly, the burner/jets replaced (which should be done anyway if you use gas a lot!).
Short-term and occasional visitors to Spain should not be affected by this carbon build-up in their appliances.
Gas is a fantastic, versatile fuel for caravanners.
The caravan gas supplier you choose may be influenced by convenience, cost and your gas consumption.
Caravanners who always use electric hook-ups may appreciate the convenience of a ubiquitous rental brand like Calor, and be prepared to pay extra for that convenience.
Heavy users quickly save money by using a refillable. I reckon I'll save over £850 on gas in a five-year period.
The figures and information I've provided will, I hope, help you to make an informed decision on how you gas your caravan. We all have differing requirements and priorities. However you do it, here's to safer and happy caravanning.