How much propane does your fridge use?

JaxDad wrote:
There's approximately 91,500 btu's in a gallon of propane. Using as an example, a 12 cu/ft Norcold refrigerator that burns 2400 btu/hr.

One gallon of propane will last about 38 hrs. if the refrigerator runs constantly.

Apparently the math portion of this calculation was lost.

If a gallon of propane will run the fridge 24/7 for 38 hours, and a 20 pound tank holds 4.7 gallons, a 20 pound tank would then run that 12 cu. ft. fridge for (38 X 4.7) 178.6 hours.

That is 7.44 days of the burner running 24/7, that is in EXCESS of one week.

So unless one has a larger than 12 cu. ft. unit, it is theoretically impossible for a fridge to burn through a 20 pound tank in a week, even if it ran non-stop for the whole week.

RJsfishin wrote:
quote:
There's no inherent reason why an absorption cooling unit couldn't be made to work directly on solar energy
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Yes there is ! Even one day w/o sun, you food is garbage !

That's a good reason to not have it work exclusively on solar energy, for sure. There should be some backup power source. The general absorption cooling process is nevertheless still quite amenable to being directly solar powered, in much the same way that low-tech solar water heating is quite practicable.

Somewhat off topic: I lived for a year in a house (in the tropics) that had a passive solar hot water setup. It worked quite well, with the only drawback being that the only days when a nice hot shower was not available were the cool rainy days when one would feel the most welcome.

RJsfishin wrote:

"You don't have a leak. You don't smell it, and you already proved that when the fridge is off. These replies are almost hilarious. Very few even mention the ambient temperature, which renders them worthless. The fridge will use much more propane when the outside temps are near 90, not to mention near 100. Then when the INSIDE temps reach somewhat more than the outside, you have more than tripled the consumption compared to a 70 degree day, not to mention maybe being under a shade tree. Lets get real, instead of misleading the OP !"

Right on! Not to mention HOW MANY TIMES YOU OPEN THE FRIDGE, daily, and, WHAT YOU PUT IN/TAKE OUT OF IT. Shade is a huge factor in cooling loads. If the outside wall of the fridge is in the sun, the frige compartment gets much hotter (solar gain) to start with. Extending the canopy over the fridge or facing the exterior wall to the north will help reduce cooling loads, if possible, north of the equator.

I know it's more work, but, unloading the fridge, shutting it off, and venting the door when not in use for extended periods is preferable to letting it run. You decide what an extended period is.

The OP never mentioned what type of fridge is in the trailer. (a key piece of info)

Chum lee

bcbigfoot wrote:
I have a 11 year old 6 cubic foot Dometic RM2652, I don't think it is as efficient as day one but it will use close to 20lbs a week in 90f + days.

There's got to be more to it than just old age.

There's approximately 91,500 btu's in a gallon of propane. Using as an example, a 12 cu/ft Norcold refrigerator that burns 2400 btu/hr. One gallon of propane will last about 38 hrs. if the refrigerator runs constantly. It doesn't though, so assuming it runs for 8 hours out of a 24 hr. period a gallon of propane should last about 5 days.

A 20 pound propane tank should hold 4.7 gallons, so it should run the fridge for about 23.5 days.

quote:
There's no inherent reason why an absorption cooling unit couldn't be made to work directly on solar energy
------------------------------------
Yes there is ! Even one day w/o sun, you food is garbage !

I found the Dometic in my 'foot was not baffled properly. The slanted exterior wall makes a baffle necessary for proper performance. See Dometic Venting

wrybread wrote:
The holy grail would be a fridge that could run on solar while the sun is up and propane at night... Now that we have cheap high wattage panels and MPPT charge controllers we're easily generating enough power from RV solar arrays. With a bit of intelligence it could over cool in the day and only kick on at night if the temp goes super high. Ice cream trucks for example run their freezers only at night and go all day without boosting.

Wouldn't a standard domestic compressor fridge, an inverter, and a sufficiently large battery bank accomplish this without even resorting to propane at night? The future (at least that part of it) is here already.

There's no inherent reason why an absorption cooling unit couldn't be made to work directly on solar energy (by heating the boiler with a solar collector), without involving any electricity. I don't know that I've heard of anyone who's actually done it, but the technology to be able to is simple enough.

You don't have a leak. You don't smell it, and you already proved that when the fridge is off.
These replies are almost harlious. Very few even mention the ambient temperature, which renders them worthless.
The fridge will use much more propane when the outside temps are near 90, not to mention near 100.Then when the INSIDE temps reach somewhat more than the outside, you have more than tripled the consumption compared to a 70 degree day, not to mention maybe being under a shade tree.
Lets get real, instead of misleading the OP !

The holy grail would be a fridge that could run on solar while the sun is up and propane at night... Now that we have cheap high wattage panels and MPPT charge controllers we're easily generating enough power from RV solar arrays. With a bit of intelligence it could over cool in the day and only kick on at night if the temp goes super high. Ice cream trucks for example run their freezers only at night and go all day without boosting.

I have a 11 year old 6 cubic foot Dometic RM2652, I don't think it is as efficient as day one but it will use close to 20lbs a week in 90f + days.