Thetford

Hi, Which power source would get my Thetford fridge down to temperature the quickest, Gas or 240v or would they both be the same?

From personal experience I would say 240v, process can be helped by putting frozen ice packs, bottles of frozen water from house fridge into the Thetford to get it to temperature

Good idea, thanks.

The evening before we set off I've started to put our van on EHU and the fridge on maximum cooling, you're then starting off with a cold fridge when I gather that otherwise on 12V the fridge doesn't get as cold. I would suspect that the freezer compartment in our Theford fridge would be colder this way than just using frozen bottles of water, cheaper though. I suppose it depends if you want to take much frozen food away with you.

Gas or 240V mains, I expect they'll have about the same cooling ability.

I have tested this on our RM4231 using dataloggers in the fridge and ice box.

Note that these measurements were conducted towards the end of April in Fife when the outside temperature was around 10C; performance at higher ambient temperatures would obviously vary. (If and when our next heatwave arrives I intend to repeat the measurements.) 

On both sets of measurements the relevant dial was set to the maximum setting. Apart from the dataloggers, the fridge was empty of contents, so this is not a true test of real life conditions.

The rate of cooling per deg C was similar to start with - both sources took around 100 minutes to drop the main fridge temperature from 10 C to around 1C.

However gas then continued downward to a much lower temperature - too cold, actually, if left on max as took the main fridge area down to between minus 6.5 deg C and minus 9 deg C depending on shelf position; the ice box to minus 20C. 

On 240V the fridge temperature varied between 1C and minus 1C, the ice box minus 10C to minus 13.5C. The temperatures vary consistently with the switching differential as the thermostat clicks in and out, whereas on gas the curve remained smooth, levelling off exponentially as it approached minimum.  I haven't tried with gas set at lower dial settings to see how control deadband varies, that's also on my list of low priority nerd jobs!

So in summary, both energy sources cool to working levels at around the same rate but gas will continue to lower temperatures. It will be interesting to see if gas copes better at higher ambient temperatures when the fridge's evaporative cycle is struggling more.

Thanks Roger,
A very interesting study.

We recently used our Electrolux fridge on gas for the first time, the thermostat was on the coldest setting and soon became too cold, crunchy salad! so we turned it down to 4 and it got even colder!! so next turned it to 3 which seemed to be just right.
When driving and fridge on 12v the performance seems to be very good, no need for freezer packs, everything nice and cold on arrival even after a short run of a couple of hours.
240v on EHU also works well, frozen stuff stays frozen so all round no complaints.
Graham