Quick guidance on LP fridge

[68camaro]

Another question, per the 2000 Concourse manual on page 12, it says that:

110V (AC) is available through "shore power" or generator, and:
12V (DC) power is available through "shore power" also;
Shore power is 30 AMP.

If both AC and DC can run off 110v/30 Amp shore power when plugged in, shouldn't they both work equally?

[caconcourse]

Another question, per the 2000 Concourse manual on page 12, it says that:

110V (AC) is available through "shore power" or generator, and:
12V (DC) power is available through "shore power" also;
Shore power is 30 AMP.

If both AC and DC can run off 110v/30 Amp shore power when plugged in, shouldn't they both work equally?

The shore power applies 110V/30 amps to the power converter/charger, which does feed the 12V DC system. It also provides direct 110V AC to a few circuits: the air conditioner, the microwave, the outlets, and the floor heater if you have one. The refrigerator is plugged into one of the outlets for AC power, and has a DC connection to the converter/charger.

They could be equivalent, except the refrigerator seems to operate much more efficiently from the AC. In all cases, the refrigeration comes from using heat to heat up the magic formula in the pipes. Propane is the best because it's a flame. AC and DC work like an electric heater with a heating element, and a 110V heating element just works better than the 12V heating element. At least that has been my observation. Maybe there is some loss in the conversion to 12V and inefficiency in the wiring.

If the refrigerator were a conventional compressor refrigerator, the electricity would be used to run a motor, and DC would work just as efficiently. In that case, choosing a compressor refrigerator with a DC motor would be preferable to an AC motor, since the battery could operate the refrigerator without shore power, or would use the shore power to provide the 12V DC as you describe.

[chin_k]

Clay is absolute right that the fewer conversion steps you do with energy, the more efficient it is. If you run it on the DC, you are generating more heat by using the converter.

If you want specifics to back up Clay's observation, here is the numbers. With AC, the heating element is ~300W. With DC, it is more voltage dependent due to the DC heating element. At 14V DC, it is about 225 W(@ 16.1A). At 12 VDC, it is around 165W (@13.8A). So there, the AC generate more heat near the burner, so it can cool the frig down faster.

[68camaro]

Clay and Chin, excellent info - thanks.

[Roly]

Another good use for the 12 VDC mode of these fridges is as a significant DC load when messing with and testing solar charging and battery functionality. Other than that all I have ever used the 12 volt heating element for was when driving. I noticed the loss of cooling effect, too.

I've cleaned and overhauled this fridge with a Dinosaur ignition board and burner, piping, and valve; now, a couple of years later, the propane mode is hicking up some. A good cleaning might be in order. If I dive into replacement, I'll definitely go with a compressor model in a bit smaller size.

Roly

[Blue~Go]

If I dive into replacement, I'll definitely go with a compressor model in a bit smaller size.

I *finally* got my compressor refrigerator installed. So I can say that the Vitrifrigo 115/130 fit really nicely. These are both ~30" tall units, and so sitting on the generator box the top allows for a really handy "bar height" countertop by the kitchen/entry/bathroom. It also doesn't stick out into the hallway to speak of which is really nice (and door handle is flush). The reason they are two different sizes is that the 115 has a built in compressor and the 130 (which I have) has a remote compressor.

I was able to add quite a bit of additional insulation to the area.

Both the 115 and 130 have the same size freezer (flap door inside main door) and the lost or gained "15" are at the bottom rear of the refrigeration compartment. But for an internal freezer it is a respectable size (.6 cubic feet).

I mounted the compressor in a cabinet just under the roof vent for the former absorption refrigerator, but it would also have fit nicely beneath the stove area in that little "groove" next to the wheelwell. These use the Danfoss/Secop BD-35 compressor.

There is a larger DP 150 (which I helped a friend install in a non-Chinook). On it, the refrigerator portion is the same 115 body but instead of the freezer being part of it, it is a separate section (with own "real" door) on top. 1 cubic foot. This would still leave more space above than the stock fridge. It would not tuck in out of the hallway quite as sleekly as the 115/130 because the door mounts proud not flush, and because I think the Chinook wall tapers inward as it goes up and you'd have to clear that. But I think it's a nice size unit. It is only internal compressor and uses the Danfoss/Secop BD-50 compressor.

(The next size up, DP 2600 also just fits but is actually larger capacity than the original fridge.)

[68camaro]

In researching for ways to make LP fridge more efficient in southern summers when boonedocking, I found a company that makes a replacement cooling systems, https://jc-refrigeration.com/product-ca ... gas-elect/ I have not called yet but will do so this week.

Does anyone have experience or heard of this company. I don't want to take out existing fridge and I use LP for most all frigeration, except occasional shore power, liker at home before heading out on trip.

[Blue~Go]

I don't really know anything about the units you posted (or about the ones I'm about to mention, so aren't I useful?), but I have "heard" good things about units called Amish cooling units. Just a possible lead.

[chin_k]

It is pretty pricey for the replacement unit, and they do not stress any efficiency with the newer unit. Let us know what you find after you talking to them.

The fin cooling fan looks pretty reasonable in price, however. I may talk to them about that.

[Roly]

Thanks, Blue, for the fridge install update. And as well, welcome back. I'm glad you're among us. I'll go look into the DP offerings.

Roly