Calor gas: propane vs. butane

[Stephen]

Hello,

I was reading the Calor Gas FAQ at:

makes the interesting point that butane boils at 0 degrees Celsius, so butane cylinders won't work in the cold.

It also says that propane should be used for barbeques and patio heaters. Is this for the same reason or is propane cheaper to produce? Surely no-one would want to be under a patio heater or be barbequing when it is freezing? Why can't butane be used?

I thought I read somewhere on the same site that only butane can be used and stored indoors and that propane can only be used indoors on a temporary basis, e.g. a plumber's blow torch. Is there a safety reason for this? Is propane inherently more dangerous? Why?

I presume that is why indoor heaters have to use butane? That can't be helpful if the temperature drops to freezing! I guess you have to turn the heater on before it gets that cold. That said, are such heaters recommended? I thought that for domestic use they cause condensation issues and didn't someone die from poisoning (carbon monoxide)? Probably best to use a fan heater if possible?

Thanks in advance.

[Harry Bloomfield]

Stephen submitted this idea :

It actually becomes unusable a little above its boiling temperature, but as it boils to vapour it draws off some of its heat. Which is why you sometimes see ice forming on bottles which are in heavy use.

See above.

Pass.

They need good ventilation and yes they do produce lots of vapour.

Yes. Not much difference in price of fuel and you do not need good ventilation to use a fan heater - much safer.

[Dave Liquorice]

Each kg of gas burnt produces a kg of water. But a kg of gas yields quite a bit of energy. 10kW springs or there abouts springs to mind so a fire running at a couple of kWhr output isn't a great generator of moisture, a cup full/hour ish.

Fan heaters don't work during a power cut... That is why we have a portable gas fire.

[John Rumm]

At high flows the cylinder will fall in temperature until there is insufficient boiler (hence pressure) to drive the supply of gas.

You need to take extra care with butane or propane. Both are heavier than air and hence can pool in low spaces rather than dispersing.

Remember the latent heat of vaporisation that is required to change the state from liquid to gas will consume significant energy. That has tom come from somewhere - typically the immediate surroundings of the cylinder. Hence it will get colder than ambient quite quickly.

Combustion of any hydro-carbon will produce water - so some ventilation is required. With an appropriate flue much of the water will be expelled with the flue gases.

CO production can happen with a gas heater where there is insufficient air for complete combustion (often recognised by a yellow flame). However this is not a reason to not use it - just a reason to make sure it is working and maintained correctly.

[Guy Dawson]

We had a BBQ when it snowed if February...

Guy

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4.4>5.4 4.4>5.4 4.4>5.4 The Reality Check's in the Post! 4.4>5.4 4.4>5.4

[RobertL]

Interesting, I hadn't thought of it like that. In fact, it makes more than 1kg of water:

C3H8 + 5 O2 =3D> 3 CO2 + 4 H2O

propane has Mol Wt. 44

4 H2O has Mol Wt 4* 18 =3D 72

So 44 grams of propane make 72 grams of water

So 1kg propane makes 72/44 =3D 1.6 kg water

Robert

[Dave Liquorice]

Except most portable gas fires burn butane. B-)

2C4H10 + 13 O2 -> 8 CO2 + 10 H2O

So produce 1.55kg water/kg butane.

[Stephen]

Thanks. I've not got or used a butane heater, so my remarks about condensation were based on what I had read. I thought that some old posts here had said you needed to run them with the windows open to provide the necessary ventilation to prevent condensation and incomplete combustion, and if the window was open it defeated the point of having a heater on. Perhaps concerns about condensation have been exaggerated?

I was wondering about getting a gas fire for power cuts and I suppose that's what started me reading up about this. However, I don't know if we have power cuts often enough to justify this. But I thought that the preferred method in this group was to hook the boiler up to a generator or inverter?

Thanks.

[Stephen]

Sorry, I was thinking about portable heaters such as:

don't have a flue.

I'm still puzzled why these use butane and everything else used propane though. Particularly if butane doesn't work at temperatures around freezing, which is when you are most likely to need to use the heater?

[Dave Liquorice]

Depends on how air tight your house is (tents/caravans I suspect are not very airtight). A modern, heavyly insulated, double glazed, box without a chimney and a room sealed boiler may benefit from having all the trickle vents opened. But older properties, assuming they don't suffer condensation normally, it's probably not a issue.

We have a gen set as well. B-) Our power is pretty good but if it does go off for more than a second or two it may well be off for 6 hours or longer. We are also on our own 11kV spur and our own transformer. Some of the poles that support the line are at "interesting" angles. If one of those, or the line, took a fall during a storm I suspect we would be at the bottom of the list to get repaired and back on grid being just a single customer.

The gen set is mainly to keep the freezers and fridges running though the power to the CH/HW system does go through a 13A plug (3A fuse) so it can be powered from the generator if required.

You must be rather hardier than us if you can live in a house approaching freezing... The bedrooms can get down to 12C during a windy night middle of winter and that is cool enough thank you. Our normal living room temp of 18C is more than warm enough to vaporise butane fast enough to drive a fire.

[John Rumm]

The power output is low enough for it not to be a major hazard as long as the room has ventilation.

Presumably you use it before it gets to freezing, and a warmish room should provide enough heat to keep the butane boiling. I have not checked, but you may find butane is cheaper as well (being lower heat output and less flexible in use due to the higher boiling point)

[Calvin Sambrook]

As others have explained butane becomes ineffectice well before the ambient air reaches 0C as the state change from liquid to gas consumes energy so the liquid cools below the temperature of the ambient air.

Yes. Propane has a higher vapour pressure so is more likely to leak/decompress at a given temperature. That's a particularly important consideration when using gas in say a camper van where it might be subjected to extreemes of temperature.

I recall once camping in South Wales in December with a university canoeing club where the butane cylinders we were using were only producing a tiny flame. We balanced one on top of the other to heat it up and make it useful...

[Clive George]

For the tiny camping ones, putting the cylinder in the pan of water you're boiling works well. And aren't lots of them propane/butane mix these days? 'course a petrol stove works whatever temperature :-)

I remember similar games with butane cylinders in static caravans (cheap caving accomodation) - fortunately they had an electric kettle, so boiling water on the cylinder was used to great effect.

[geoff]

In message , Stormin Mormon writes

Top posting jesus mong ...

You put your reply, including sig sep above the previous post, so it disappears from the reply

Go look at the alpha course, and partake in the survey

The generator makes more noise, and attracts attention. The

[Mike Barnes]

Calvin Sambrook :

Sounds familiar. I remember camping in Scotland and keeping the butane cylinder in the bottom of my sleeping bag to ensure a hot cup of tea in the morning. Even so it was a bit slow, so I placed the (large, hose- connected) cylinder on top of the pan.

[PeterC]

In our hut near Capel Curig we were cooking breakfast on 1 burner with the butane cylinder on the other burner (I put it there). Some alarm re. possible explosion until I pointed out that the ice on the side meant that the cylinder might be cool.

[geoff]

In message , Stormin Mormon writes

You're a top poster

And they all go to hell

[geoff]

In message , Stormin Mormon writes

No - forced to sit inbetween drivel and dennis for eternity

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Stormin Mormon" saying something like:

Or, just as I have done for several hours today because of a planned maintenance outage, hook it up to a running vehicle and power the basic essentials - TV, PC, etc.