We had a gas continuous hot water system (with 2x 45KG LPG bottles) installed in October last year. We also had gas pre-piped under our kitchen in preparation for a kitchen renovation which has subsequently been put on hold, so as it stands at the moment the only thing we use gas for is hot water. There are only two of use in the house and we do mainly cold clothes washes.

We don't have temperature controls in kitchen or bathroom, it is set at the unit to 55 degrees and we just mix in cold to get the desired temperature.

We aren't using hot water any differently, but have had significant variation in how long a gas bottle lasts, with the last two being especially quick to deplete.

Bottle Replaced        Days Lasted

5/10/2016                   46

20/11/2016                 49

8/01/2017                   75

24/03/2017                 53

16/05/2017                 41

26/06/2017                 35

31/07/2017                 35

I haven't properly weighed a bottle after the valve switch over to see if it is really empty, but I have physically lifted it and it feels pretty empty to me.

Could this large variation be attributed to it requiring more gas to heat the water in Winter, since presumably the cold water coming in is colder than in Summer?