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GAS OR OIL ?


Jacqui      Too
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I have never seen the reason for having to have propane bottles outside. The only differences that I know of are the 'non gassing' temp of propane = -40C, butane = 0C and the calorific value. Propane has a slightly higher value. But they are almost the same gas? Or am I missing something here?

As said before, it will be impossible to police and the only time it will have any effect is if there is a fire nd the propane bottle is found inside! Mind you if it's a big enough fire it won't be found within miles [:-))]!

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[quote user="Gluestick"]

Most gas cookers use bottles, anyway, although, of course, if you decide on gas and have a large storage tank fitted, you can run your cooker from this. Nothing preventing you from oil heating and bottled gas for cooking.

Ours is pretty well adjustable and runs from a large butane bottle, which lasts for ever and costs circa € 24 for a refill. The once only deposit is also round about the same price.

When you say "Big bottle" what size are you thinking? It is normal to operate heating from a very big storage tank, supplied and fitted by the gas supplier and you only pay an annual rental thereafter.

 

[/quote]

We have the same arrangement - oil fired central heating and bottled gas for the hob.  Our hob (a smeg) is very controllable and the (quite small) bottles last us ages.  Our gas bottle fits in the kitchen base unit under the hob. While we were looking at properties we came across a couple of places that had wood fired central heating.  I have no idea how efficient these are / how much wood they consume so can't give any numbers - but we were told that this was a good cheap alternative to gas / oil.

We have had an induction hob in the UK before we bought our range and I didn't like it - but that's just personal preference.

Kathie

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[quote user="Gyn_Paul"][quote user="Will "]Butane cannot be stored outside in winter because of its freezing point. Only propane, as Gluestick says.[/quote]

Storing it outside isn't a problem; it's just using it !

p

[/quote]

Very strange this, we use butane, bottle(s) stored outside, last winter when in France we cooked daily (as you do!) and logged a temperature of -8.5 degC at 0930 one morning. Gas still working - most odd    [8-)]

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Putting my techy head on for a bit.

Butane freezes at -138C

Propane at -190C

What is being referred to is the Boiling point, ie, the point at which the liquid refuses to turn to gas, and therefore unable to be used.

The boiling point of butane is -0.5 C.

The boiling point of propane is much lower, at -42.1 C.

[;-)]

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[quote user="powerdesal"][quote user="Gyn_Paul"][quote user="Will "]Butane cannot be stored outside in winter because of its freezing point. Only propane, as Gluestick says.[/quote]

Storing it outside isn't a problem; it's just using it !

p

[/quote]

Very strange this, we use butane, bottle(s) stored outside, last winter when in France we cooked daily (as you do!) and logged a temperature of -8.5 degC at 0930 one morning. Gas still working - most odd    [8-)]

[/quote]

Is the bottle in the sun,  by any chance ?  It's amazing how much radiant heat dark painted bottles take up.  Also, if you're only using a couple of rings then the bottle and regulator can often take in enough heat from its surroundings to compensate for the latent heat loss needed to boil off a small amount of gas. However when there is a large demand (like for a multipoint water heater, for example), the set-up freezes (I reckon it's where the high pressure liquid turns into a low pressure gas either side of the regulator, just like a fridge).

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Cant fault your logic Gyn_Paul, but bottles are bright yellow. Out of the wind, may have been some radiant ambient effect, certainly by lunchtime. Gas pressure was noticably lower than summer normal. It never created a problem though, only time will tell. I have an aversion to gas cylinders indoors. Your point about high flow freezing is well made, I'm digging back into thermodynamics memory but seem to remember something about Bernoulli, or was it some other foreigner?   [:)]

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It might be impossible to Police but would your insurance be valid if your house burnt down and a gas bottle was found inside, me thinks not, we weren't preparred to risk it a bit like if you had a chimney fire and couldn't prove you had it swept the insurance companies won't pay out. I don't suppose at this point there is much clarification on just what the rules are like with swimming pool fences they'll just make it up as they go along when they've had time to think it through!!!
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I also have been digging into the dim distant recesses of what passes for a mind, these days![8-)]

I think it is all a matter of latent heat. Since nothing is for nothing in the world of physics, when you open a pressurised container to either atmosphere or a lower pressure environment (i.e. via the regulator), in order for the stored gas to undergo a change of state (i.e. from liquid to gas) this requires latent heat.

The body of gas absorbs latent heat through the bottle walls from the outside. If there is not sufficient latent heat capacity, to overcome the natural temperature drop caused by the expanding gas (Boyles Law- hmmm or is it Charles Law?? Or even a bit of both??), then the liquid will not boil and release free gas.

If a large volume of gas is extracted fairly rapidly the bottle cools and can even form ice on the exterior. (Feel your gas bottle with the oven on!).

Additionally, as GP states, there can be a freezing effect caused due to the pressure differential within the regulator. Same as a carburettor icing; this is caused, again, by latent heat extraction: same principle as a refrigerator, where to expand the coolant gas in the evaporator, it forms exterior ice[8-|] as it extracts latent heat from the inside of the 'fridge.

I think? [blink] I dunno anymore; My brain hurts now.[blink][8-)]

 

 

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Umm, yes Dick, Bernoulli's Principle and Venturi Tubes and Carburettors: coming back now, sort of.

The jet is normally placed in a constrictor and as the air accelerates on the other side, you can actually see the fuel atomising. SU carb and take the air filter off and crack the throttle.

Aerofoil Sections: Lift: http://www.ae.su.oz.au/aero/aerointro/what_is_lift.html

Hmm and this as well, a bit. Making me think of 36 years ago and aerofoils (wings) on single seaters.

 

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Dick, that was a rotten thing to do: you've had me spent an hour drilling deeper and deeper into endless pages of Wiliepaedia et al learning more and more about venturi , lift and drag.

I think I sort of begin to understand it. Just don't anyone ask me any questions for a while until I've processed it all.

I still don't understand how you can get lift out of a flat surface though !

p

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Just to throw something in from the side - have you considered electric heating?

Electric is cheap here (according to our latest EDF bill 85.8% is nuclear - hence not dependent on oil/gas price) we have a very effective electric heating system (now that we've managed to upgrade our supply from 6Kw!)  It is very cheap (and easy) to install, and very flexible in its use.  It can be installed to be controlled just like "normal" central heating systems with all the options you would be used to.

I spoke to quite a few people about it who already live in the local area before deciding, and many of them recommended electric (including the French locals) - or stated they wished they had gone with the electric option because of the price of oil/gas[/wood]

Matt

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It cost us twice as much to heat the house with oil the winter before last as it cost us to heat it by wood last winter (dual fuel boiler).  Bear in mind that was using oil before the oil price hikes.  Wood varies enormously in cost depending on local supplies.

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[quote user="Gluestick"]

(Boyles Law- hmmm or is it Charles Law?? Or even a bit of both

[/quote]

Boyle's Law:

P1 V1 = P2 V2

  T1         T2

As in P1xV1 divided by T1 equals P2xV2 divided by T2.

So, assuming temperature inside container and outside is the same, then this makes sense - open the regulator, you increase the volume, but decrease the pressure (as liquid turns to gas). However, irrespective of the ambient temperature, the temperature inside the bottle will always be lower in this case, as the gas is in its liquid state inside the bottle, therefore at a lower temperature (as in water is at a lower temperature than steam). So, unless you know the gas pressure and temperature inside the bottle, compared with the gas temperature and pressure at the nozzle, prior to combustion, then this is of little use.

I've forgotten Charles's Law, so can't advise if it is of any more use, but I have my suspicions.....

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Dick an aeroplane will fly because if you look at the handbook that comes with it then you wil find that when it gets to a certain speed it will lift off! If it doesn't then you have a right to climb out of the wreckage at the end of the runway and file a complaint. Just make sure that you take the hand book with you! If you were to blow over a sheet of paper, of course it would rise. With all that hot air and the authority of a senior teacher it wouldn't dare not [:D][Www][kiss]!

Our rented house was all electric and I have not been so cold in all of my life as we were the winter before last when we were in there!!! You could have made ice cubes on the floor. It was expensive and didn't work when we had power cuts either!

Now we have low temp, LPG, underfloor heating. That won't work either, I hear you cry, when you have a power cut. But it will, because we have a battery powered inverter that will run the pump and boiler!! Besides that it would take at least 24 hours before the floor would show any cooling even with no heatng applied.

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[quote user="Wozza"][quote user="Gluestick"]

(Boyles Law- hmmm or is it Charles Law?? Or even a bit of both

[/quote]

Boyle's Law:

P1 V1 = P2 V2

  T1         T2

As in P1xV1 divided by T1 equals P2xV2 divided by T2.

So, assuming temperature inside container and outside is the same, then this makes sense - open the regulator, you increase the volume, but decrease the pressure (as liquid turns to gas). However, irrespective of the ambient temperature, the temperature inside the bottle will always be lower in this case, as the gas is in its liquid state inside the bottle, therefore at a lower temperature (as in water is at a lower temperature than steam). So, unless you know the gas pressure and temperature inside the bottle, compared with the gas temperature and pressure at the nozzle, prior to combustion, then this is of little use.

I've forgotten Charles's Law, so can't advise if it is of any more use, but I have my suspicions.....

[/quote]

The temperature inside the bottle, when the valve ( any device connected) is closed, will always be identical to the external ambient temperature, once its condition has stabilised: if not, then the bottle would "Give off cold"! Since cold, per se is the absence of heat - in relative terms - rather than physical (Kinetic) energy (Remembering that energy can either be Kinetic or Potential and that energy cannot be lost [law of Entropy] it can only be transmuted: ie.electricity to light; heat etc.), cold does not exist.

Excepting according to my dear old Mum, of course, bless her, who always used to say, "Shut the door! You're letting the cold in!" She could never be convinced that actually, we were letting the heat out!

Gasses can be induced to undergo a change of state by either being under pressure or being frozen by extracting the heat stored at the time.

Actually, I am beginning to feel the Butane/Outside/ Cold/Won't Work thing is explained by Charles- Gay-Lussac's gas law, rather than Boyles, 'cos Boyles sets out the direct relationship between pressure and volume:

Finally, if the mass and pressure are held constant, the volume is directly proportional to the temperature for an ideal gas. This relationship is called  Charles and Gay-Lussac's Law, in honor of the two French scientists who discovered the relationship.

Possibly................. [8-)]

 

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Hi Chippie, I have an idea [I]. If  we get together and bottle Gluestick, Wozza and anyone else that has been spouting all this hot air neither of us would have to worry about gas or oil for heating or cooking!!![:-))]. Talk about things gassing, this lot holds the record in my book [6][:D]. Sods Law is more in my line of work!

How come nobody's mentioned my mate Aidi Abatic-Expansion. That cools a gas tooo peut etra?

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I'm sure the efficacy of electric central heating is totally dependent on the particular system.  Our thermostat is set at 19.5 during the  day and 21.0 in the evening for about 4 hours.  I have no reason to believe it's wrong.  The house seems very warm to me and I'm chilly mortal, Mr Cooperlola even more so!
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  • 1 month later...

I think I have just answered my own post. I found this on a web site for log burners.

Hope it helps others make up their minds, I know which one I'm going for.

Comparatif des prix d'achats des énergies pour le particulier en centimes d'euros par kWh

 

 

 

 

2004

2005

2006
  Electricité

11,7

11,7

11,9
  Gaz propre

7,6

9,1

10,6
  Fioul domestique

4,5

5,8

6,8
  Gaz naturel

4,1

4,5

5,2

Bois (moyenne nationale)

2,9

3,2

3,5

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