Gas

[Allan_5039877]

We recently spent a few days in our caravan, and as the weather was very cold used the gas fire a fair bit. To my surprise I found a new 7kg cylinder lasted 1 day! This was using the fire for several hours, most of the time on a medium setting, water heater for 2 or 3 hours and the cooker for boiling the kettle. Is this about right? Any thoughts will be appreciated.

Ray

 

[ProfJohnL]

Hi Allan,

Gas consumption should be quite easy to predict, as most appliances these day should state on their data plate how much they use, so for example a Truma 3002 (3.2kW) will use 280g gas/hour on high setting a water heater rated at 1.2kW will use about 105g/h as a rough guide if you assume 100g/h for every kW you won't be far out.

 

[rayc]

Allen, I think there is a problem somewhere. Your gas usage for the heater and kettle was negligible. The medium setting of the heater is say 1.5Kw. In my experience ( a bit hazy now due to electric hookups) I would expect 3-4 evenings, of say 6 hours per evening, on a 7kg propane cylinder under the circumstances.

 

[rayc]

Allan, just a further thought, you say it was very cold I assume you were using Propane? Ray

 

[ProfJohnL]

Hello again Allan, Ray has made a very good point, one of the characteristics of Butane (Calor gas blue bottles)is that the the liquefied gas in the bottle has to keep vapourising to maintain the gas pressure. This process uses the latent heat of vapourisation, which it draws from the body of the liquid in the bottle. Using gas will cool the liquid (have you seen frost on bottles of propane that roofers use?) For Butane if the temperature falls below about 0C the liquid will not vapourise and the gas pressure falls to zero. Propane has exactly the same effect but it stops vapourising at about -40C, which is why it is preferred for winter use. Do not thermally insulate the gas as it relies on being able to draw heat from ambient air around it to keep the gas vapourising.