3 WAY FRIDGE GAS USAGE.

Submitted: Monday, Jan 13, 2003 at 15:48

ThreadID: 2939 Views:28699 Replies:8 FollowUps:3

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Rob

I have a 3 way 90L fridge in my Jayco wind up camper. The gas bottle is a 9kg bottle. How long will a full bottle last whilst running the fridge on gas. I imagine there are many variables, such as ambient temp and thermostat setting.
Lets say 25 - 30 deg ambient and thermostat set at half way.
I have no idea how long it will last, 3 days or 3 weeks. A rough idea will be very helpfull
Thanks for any helpfull comments
Rob.

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Reply By: ThePublican - Monday, Jan 13, 2003 at 16:16

Monday, Jan 13, 2003 at 16:16

Got an old 50 lt chescold that did not fully use up a 4.5kg bottle on our last 5 week trip,was on gas for a minimum of 16 hrs per 24hr period,rest of time on 12 volt as on the move.

AnswerID: 11185

Reply By: Peter S - Monday, Jan 13, 2003 at 16:28

Monday, Jan 13, 2003 at 16:28

Also try fitting a pc fan on the top vent mount a switch in van to turn on/off.

Most van do not alloe enough air space arrounf fridge so by helping the hot air out of this space will aid cooling and reduce gas consumption by about one third.

AnswerID: 11187

Reply By: OziExplorer - Monday, Jan 13, 2003 at 16:56

Monday, Jan 13, 2003 at 16:56

Rob that fridge will use 350g/24 h approximately in summer, and as low as 250g/24 h in winter.
I would suggest you get a digital thermometer from Dick Smith Electronics like part no: Y5007 $29.88 www.dse.com.au
This will allow you to keep your fridge between 4°C and 6°C and not waste gas having it to cold or spoil food having it to warm. If you are filling it up with drinks/cold water/UHT milk etc. always try to do it at night.

I don't know if you realise the importance of having that fridge as close to level as possible. For an absorbtion fridge to work efficiently it is imperitive it is level. A small round bubble level can be purchased at most hardware stores, and can be placed just inside the camper door to allow you to set the camper up level. Some pieces of 17mm formply 300 x 180 are always useful to have to level the camper up properly.

AnswerID: 11189

Reply By: Phil - Monday, Jan 13, 2003 at 18:32

Monday, Jan 13, 2003 at 18:32

Rob,

I have a similar fridge in our Jayco Swan Outback.

We recently used the fridge exclusively on gass for 12 days 24/7. We also did all the cooking for a family of 4 that included some breakfasts and some dinners. The gas ran out about an hour before I intended to switch it off. We were very impressed with the way the gas kept things cold and will continue to use this method

Cheers

Phil

AnswerID: 11206

Reply By: rodeoowner - Monday, Jan 13, 2003 at 19:23

Monday, Jan 13, 2003 at 19:23

Hopefully you still have the fridge instruction manual. If not there will be a compliance plate on the rear of the fridge. There will be a gas usage figure in MJ/h. Depending on the size of the fridge it will probably be 2-3 MJ/h. For example, most of the 40-60 litre Chescold 'eski' fridges run at 0.85-1.05 MJ/h. Take the kg rating of your gas bottle and multiply it by 50. This will give you the Mj/h capacity of your bottle. Then divide this figure by the Mj/h rating of your fridge. This figure is your run time in hours.

ie. 9kg x 50 = 450
450/3 = 150 hours run time.

This figure will give you an indication of the run time you can expect. Whilst the fridge does work on a thermostat, the difference in Mj/h from high to low will be minimal.

Hope this helps (and doesn't sound too complicated).

Cheers.

AnswerID: 11211

Reply By: Rob - Monday, Jan 13, 2003 at 20:54

Monday, Jan 13, 2003 at 20:54

Many, many thanks for all of your helpfull comments and hints. I will certainly look at adding a fan, at the rear of the fridge, for better cooling.
Thanks "rodeoowner" for the calculation.

Again, many thanks,
Rob

AnswerID: 11224

Reply By: clint - Tuesday, Jan 14, 2003 at 04:35

Tuesday, Jan 14, 2003 at 04:35

just a bit more info for you
it will not make any difference whatever the temperature is or whatever the thermostate is set at when your fridge /freezer is on gas
the small flame which cools your fridge is always using the same amount of gas regardless of the settings hence the flame is always the same and the themostate controls the temperature but not the flame

AnswerID: 11250

Follow Up By: Oziexplorer - Tuesday, Jan 14, 2003 at 11:52

Tuesday, Jan 14, 2003 at 11:52

Clint that information is most definitely not correct concerning the brands of Electrolux, Dometic, Chescold, Finch and Consul absorbtion fridges.

The thermostat most definitely reduces the amount of gas to the burner and does not control in any way any other part of the absorbtion refrigeration system.

When the tempreture of the fridge gets up to the pre-set range, the thermostat reduces the amount of gas to the burner. However, to the naked eye it is difficult to see any difference in the flame, but the thermal heat (BTU's) from the flame is considerably reduced.

On 240vAC the thermostat controls the heating element.
On Gas the thermostat controls the volume/amount of gas supplied to the burner.
On 12vDC it is flat out all the time, but if you are using the fridge on 12vDC all the time, it is easy to hook up a small relay to use the existing thermostat.

FollowupID: 6208

Follow Up By: David - Tuesday, Feb 11, 2003 at 12:55

Tuesday, Feb 11, 2003 at 12:55

Gotta agree with oziexplorer on that one.

12v it runs continuously- gas and 240v it's regulated and gas consumption varies a lot.

Not only will it not work if off level, you'll also damage it permanently. It overheats the ammonia solution and crystals form if circulation stops for too long. These will then block orifices and hey presto it's kaput. Very expensive to repair. (moving is OK- just don't park for long with it off level and switched on.)

Summary- it MUST be level and must have very good ventilation. I work on about 400-450 grams a day, but this will vary depending on the fridge. ( carry a spare 2kg gas bottle and have the appropriate adapter to mate up to a POL fitting- that will give you an extra 4 days at a pinch.)

Finally, if you ever upgrade look at a 12v compressor fridge. It is better in EVERY respect than 3 way( exept it won't run on gas.) Pack a suitable battery and solar panel and you can refridgerate forever in the bush and gas is then not a problem.

FollowupID: 7506