Is all LPG Gas the same (heat wise)?

[Blocklayer]

Since the new gas bottle, the gas cooktop seems not as hot. It takes longer to boil water.

Is all gas the same, heat wise? Can it be cut?
All the valves are on full and the burners are clean.

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[malb]

Assume you are talking LPG rather than Natural Gas as you mention a recent bottle change.
LPG is a mixture of Butaane and Propane, two gasses which have different heat outputs. A variation in the mix ratios will thus affect the heat output.
As I understand it, there is not an officially regulated composition for LPG so suppliers are free to juggle the proportions in the mix to accomodate supply situations.

[DJ’s Timber]

Depending on demand, they quite often up the weaker gas here in Australia whilst they sell the better one overseas during the summer period and then for winter vice versa.

It's all about getting maximum dollars all year round.

[RETIRED]

Assume you are talking LPG rather than Natural Gas as you mention a recent bottle change.
LPG is a mixture of Butaane and Propane, two gasses which have different heat outputs. A variation in the mix ratios will thus affect the heat output.
As I understand it, there is not an officially regulated composition for LPG so suppliers are free to juggle the proportions in the mix to accomodate supply situations.

Not quite. http://www.lpgaustralia.com.au/displaycommon.cfm?an=15