butane Vs propane

[Rubix]

And in the blue corner ....

I have searhced the forum for the answers I am looking for, but so far no joy. Can anyone help ?

I understand the difference between the two, but I was wondering is there anyone who uses both regularly ?

1. As butane seems to cost more (7kg butane £15.49 Vs 6kg Propane £14.49 on calor website) is it used at a slower or faster rate, therefore given a certain useage which would last longer.

2. I have read that butane "burns hotter" does this make it more efficient in terms of cooking quicker and heating "warmer" when using a gas space heater.

3. If anyone uses both (butane in summer and propane in winter) do they notice a difference in terms or 1. (cost) and 2. efficiency) above ?

4. I have also heard that one has a higher calorific value, but somewhere else said there was no difference. Does this relate to the "burning hotter" thing ?

Thanks

 

[JeremyClarksson]

It seems to work out that small bottles are slightly cheaper per KW/hr for butane with larger propane bottles being cheaper than butane.

We can get 13kg bottles in the front locker so use propane.

I worked out the table below some time ago so bottle prices may be a little out.

Bottle..(Kg).....price (pence).....KW/h per Kg.....pence per KW/h

Butane....7......1499..............13.62............15.72

Propane...6......1399..............13.83............16.86

Butane....15.....2049..............13.62............10.03

Propane...13.....1749..............13.83.............9.73

 

[Rubix]

Garry,

So the KW/h figures indicate that more (but only just) energy (power, whatever a watt is in gas terms) is available from Propane.

Is this the calorific value ?

 

[Cockovan]

Hi Rubix,

We used to use both (summer/winter) but never bothered to work out costs/value for money. I got fed up with changing the regulators and storing the spare bottles so we now use propane all year, here and abroad.

Alan

 

[rob_jax]

Hi Rubix,

1. In the pricing example you quoted, the price per kg is about 10% more favourable for Butane - so in that case Butane is cheaper.

2. Phrases like "burns hotter" are layman's ways of trying to understand the technical issues, and they don't really help.

The real difference is that Butane is around 10% more energy dense than Propane, so you'll use 10% less fuel to boil a kettle or any other task if you use Butane.

You won't notice any real difference in heat output from the Truma heater - it's thermostatically controlled - so you'll just use a bit (10%) more gas running on Propane.

4. You may have seen the calorific value quoted by volume of gas burnt or by weight of gas burnt - these differ by the 10% energy density figure I mentioned earlier.

In terms of real use - use whatever works best for you - saving 20p per kg of gas used is hardly likely to be the most important cost you'll have on vacation.

Robert

 

[ProfJohnL]

Hello Rubix'

I can understand your misunderstanding about the differences between Butane and Propane, and the various pros and cons for each. As we are concerned with caravans, I will assume we are only considering the 7Kg Butane and the 6Kg Propane bottles

In simple terms you want to know how long each type of bottle will last -assuming the same usage, and are they directly interchangeable.

The 6kg Propane bottle actually holds about 15% heat energy than the 7Kg Butane, So you may notice the propane running out slightly earlier than a Butane.

As for efficacy, the that will depend on how old your gas system is:

Historically in the UK we used to have two regulator pressures. Butane @ 28mB and Propane @ 37mb. This differentiation of pressure allowed the majority of gas appliances to work equally well on Butane or Propane. The pressure difference offset the other factors that affected the performance of both gasses.

Now we have adopted a single standard pressure of 30mB for both gasses. This now means that pressure pushes a little more Butane through each appliance than before, but there is a reduction of Propane. This will manifest itself, as a kettle will boil quicker on Butane than on Propane.

This does not mean that Butane has a hotter flame temperature than propane, its just a bigger flame.

You will not notice a big difference with thermostatically controlled gas valves as used on space heaters, because the valve opens and regulates the flame size according to demand. The gas valve will automatically compensate for the reduced heat input of propane by either opening up the valve more, or for longer.

In the UK there is no problem with using Propane all year round, Butane can be difficult in winter where the bottle gets too cold to allow the LPG to produce vapour at around 0 degrees C.

There is a difference between the calorific values of both butane and propane, but the difference is reverses depending on if you are using volume or mass, it all to do with the relative rates of expansion. So don't worry about it.

 

[BeemerMal]

Rubix....We use mainly mains electric sites so our gas usage has gone down quite considerably in the last few years so the price differential between the two types is marginal.

We changed from butane to propane a couple of years ago to suit all year caravanning but had a problem at the time with Calor Gas who refused to exchange 7kg butane bottles for 6kg propane.

They expected me to enter into a new contact to buy the new bottles because my original (initial) purchas was more than 7 years ago? Although they did say they would take the empty butane bottles off me free of charge...that was good of them!

However, a friendly Calor dealer did swop them over saying it made no difference to him. All he needed was a bottle in to replace a bottle out. I only paid the price of the gas.

If I was looking to change over now I would go over to the lightweight BP gas.

 

[ANN_374233635]

Rubix....We use mainly mains electric sites so our gas usage has gone down quite considerably in the last few years so the price differential between the two types is marginal.

We changed from butane to propane a couple of years ago to suit all year caravanning but had a problem at the time with Calor Gas who refused to exchange 7kg butane bottles for 6kg propane.

They expected me to enter into a new contact to buy the new bottles because my original (initial) purchas was more than 7 years ago? Although they did say they would take the empty butane bottles off me free of charge...that was good of them!

However, a friendly Calor dealer did swop them over saying it made no difference to him. All he needed was a bottle in to replace a bottle out. I only paid the price of the gas.

If I was looking to change over now I would go over to the lightweight BP gas.

Rubix

we use Propane all year round; elec hook-ups mean we use less gas, so we carry 1 x 3.9kg cylinder - this helps keep noseweight down.

If you need a different size cylinder, try "liberating" one from your local recycling centre, and taking this to Calor for exchange!

Ann

 

[JeremyClarksson]

Rubix

KW/h is not a measure of calorific value as this relates to heat and KW/h relates to energy but there is a rough tie up between the two.

Propane is choice for me because

1. There really is little difference in cost per heat unit.

2. I do a lot of winter rallying.

3. I do not want to keep changing the regulator

4. I have always found the clip on regulators a pain in the proverbial donkey.

My personal opinion is if you are thinking of winter use make the change and do not bother changing back.

 

[Garfield]

This is the boring scientific bit,

Methane (natural gas ) is one carbon with four hydrogens attached, this requires very high pressures to keep it liquid at normal temperatures, next is ethane then propane which is a row of three carbons then butane which has four, each carbon has two hydrogens attached apart from the two at the end which have three. as the row of carbons gets longer, the boiling point rises so when the weather is cold, butane doesn't boil at all and stays as a liquid in the bottle.

Carbon produces more energy than hydrogen when it burns this is why butane produces more heat than propane as it is proportionally richer in carbon, this is also why, when both gasses are supplied at the same pressure to the cooker butane boils the kettle quicker, not because the flame is bigger. The higher regulator pressure for propane was probably to compensate for its poorer energy value.

The bottom line is that if you do use a lot of gas in the summer then it is worth swapping between the two as in smaller bottles, butane is cheaper, even in 15kg bottles the butane is cheaper per unit of energy. If you only caravan in summer then stick to butane. If you don't use much gas and use the caravan when it is regularly less than 10'c then stick to propane unless it is really that easy to swap between the two in newer caravans.

 

[Rubix]

Thanks for all your replies, I was overwhelmed

rob_jax : I agree with you about the layman terms bit, but unfortunately, being new to this me is definitely one of those lay-people. I am a quick learner and have changed my ways just kidding.

When I said space heater, I meant gas heater (my van is a '98 build so is not warm air, did I get my terms wrong (damn those lay people ) so I didn't think they were thermostatically controlled, just a knob on the front - big flame, small flame, anyway.

John L - I have an older van and so need two different regulators (which I already have for the two different cylinders), but I understand what you are saying, they are as near as damn it the same.

Garfield - you explained that very well, I understood what you meant (I am an engineer (not gas though), so that helps).

So put simply as cost is pretty much the same, it is down to summer (marginally lower cost) vanning - use butane Vs all year or winter vanning - use Propane (and of course you are able to cook/heat etc in the snow!).

As I have a 7Kg Butane (new) and a couple of old smaller butane and propane cylinders, I am thinking of swapping the smaller propane for a bigger one and then I can have that as a winter cylinder. I can then use the smaller butane as a back up. As the only inconvenience is with the aid or a screwdriver (jubilee clips) I could swap from one cylinder to the other.

If it is raining I can get SWMBO to hold the umbrella while I change it (sorry ladies).

Or if I find we start rallying in the winter I might just sod it and get two large and one small propane cylinders (small as a backup) and then get a changeover tap (she can still hold the umbrella though )

My apologies for the essay, but as you have all explained so well I like to give you all thanks.

Thanks again