Resi fridges in more and more units

landyacht318 wrote:
My one 800 watt MSW inverter uses 0.68 AH each hour, turned on, powering nothing.

0.68 amps per hour is a high level of no load input current for that size of MSW inverter.

This 800 watt MSW version of the popular Samlex line of inverters only consumes 0.25 to 0.35 amps per hour: http://www.samlexamerica.com/documents/product-specs/12002-SAM-800-12-1113%20Lrez.pdf

Shame that the Danfoss powered 12-24v DC compressor fridges are so expensive, because they will use about half the electricity as a residential fridge on an inverter will.

I got a 1.8 cubic foot fridge with a danfoss BD35f compressor, that has extra insulation, and a very well ventilated condenser, and it averages 0.62 Amp hours per hour consumption in 75F ambients as I use it, and my Door seals are questionable and could easily be improved upon.

My one 800 watt MSW inverter uses 0.68 AH each hour, turned on, powering nothing.

Well that comment went sideways
What i said simply meant
For a given amount of time AKA one week
A person will spend less money for LP fridge cooling with LP, than burning gasoline in a generator for compressor fridge cooling
Or heating the RV fridge with electric heating element, using Genny directly,
Electric efficent or not, it's not cheap for an RV fridge
a residential uses less electric energy than an RV fridge

To add to that
it all changes if you have the battery bank and solar
Operating costs come closer together

The compressor fridge will almost always out do the RV fridge on cooling capability regardless of operational costs



I've been using a compressor fridge for 7 years, i have no complaints

I also had no complaints about the RV fridge in previous RVs
But this one was DOA, and the repair did not last
After several trys, i switched to the residential fridge

I like not worrying about being level in parking lots, rest areas, event parking etc..

Converting gasoline to mechanical energy, then to electrical energy
Incurrs losses those losses add up if done 24/7

But doing them at higher rate, heavy load recharging, makes the system more cost effective

It's all a matter of balance

MrWizard wrote:


LP does offer the most time for the energy cost
it does NOT offer the best cooling,

It is not that simple.
When propane Energy is the cheapest mostly available (that can change in different location) when burning propane you have burner efficiency about 40-50%, so about 1/2 of your cheaper energy goes up the chimney.
Electric elements on fridge on other hand are well insulated, so close to 100% of their energy goes into process.
I did 3 day tests on my Dometic in 100+ F heat and even propane mode gave me additional 2F of cooling, that falls into error margin aka the weather could change.
On my latest fridge 120V seem to get lower temperatures than propane, but later I discover that PO add lot of wind shields to fridge vents, who cut down the efficiency.
Bottom line, each propane burner can have different output and different models have different 120V elements.
12V elements are smaller by the design.

Speaking of Level and Shoemaker Installation... Be sure the Fridge is Level WITHIN a Level Coach. If it's mounted on a plane that's a few degrees different from the coach floor (or whatever your leveling reference is) then you'll be comfortable but the Fridge will be camping a few degrees off.
The Fridge is Customer One when it comes to Leveling!

pnichols wrote:

MrWizard wrote:
LP does offer the most time for the energy cost
it does NOT offer the best cooling,

I heard a quote once that goes something like: "Perfection is the enemy of good enough."

Our Norcold propane refrig is only a little over 6 cu ft. (I think), so maybe smallness in propane RV refrigerators is the magic key ... as our Norcold cools just fine with it's 5 coldness settings. We never need it's maximum coldness setting of #5, and it's setting #4 sometimes is too cold in all but the very hottest weather. We usually need to have it set on it's coldness setting of only #3.

For us for some reason or combination of reasons, our two-way Norcold propane refrig has certainly been a stellar "good enough" performer. I wonder if the reason is it's modest size, or it's proper installation by Winnebago, or it's manufacturing date of being built back when quality was still present in RV appliances?

It's ONLY fault has been that for overall long life it needs to be kept somewhere near level when camping - and until they mount RV propane refrigerators on gimbals (as they should) - this is the only thing that keeps it from being hands-down far superior to a compressor refrigerator's unending energy requirements when drycamping.

For what it's worth, I believe that a somewhat spectacular person from history with a last name of "Einstein" coinvented the gas absorption refrigeration process.

Most cooling problems with absorption is due to the RV manufacturer. Norcold, Dometic, and Atwood all have very specific venting requirements and RV manufacturers seldom follow them, doing a half cocked job of the construction of the cavity behind and above the unit. Its the same principle as a masonry chimney. Hire a shoemaker mason to build it and see what you get when it does not create a draft. Also, mounting them in slides where the upper vent is in the sidewall is even more problematic, and requires mechanical ventilation (fans). Despite Dometic (not sure on Norcold) having fans at the cooling unit for a slide application they are usually not sufficient due to their mounting location. Movinv air that was pulled in the lower sidewall vent, does not like to flow up over the fins of the unit, then turn 90 degrees to exhaust out the sidewall vent. If you have an absorbtion fridge that has lackluster performance in a slide, add two 120mm fans to the upper vent panel itself ejecting air out and you'll increase the performance substantially.

As far as out of level/plumb. All manufacturers recommend they be within 3 degrees plumb side to side of the fridge and 6 degrees plumb front to back. The side to side is most critical because of the slope designed into the tubes, for the ammonia to flow back to the evaporator when condensed. With the fridge typically mounted at a sidewall typically, purposely put your rig 3 degrees out of level front to back and see if you would use it that way. It's more than most people think.

If I knew I was always going to be at sites with hookups, or had a rig set up seasonal, residential would be a no brainer I guess. That's not the case and solar would not be an option as we camp in the woods.

MrWizard wrote:
LP does offer the most time for the energy cost
it does NOT offer the best cooling,

I heard a quote once that goes something like: "Perfection is the enemy of good enough."

Our Norcold propane refrig is only a little over 6 cu ft. (I think), so maybe smallness in propane RV refrigerators is the magic key ... as our Norcold cools just fine with it's 5 coldness settings. We never need it's maximum coldness setting of #5, and it's setting #4 sometimes is too cold in all but the very hottest weather. We usually need to have it set on it's coldness setting of only #3.

For us for some reason or combination of reasons, our two-way Norcold propane refrig has certainly been a stellar "good enough" performer. I wonder if the reason is it's modest size, or it's proper installation by Winnebago, or it's manufacturing date of being built back when quality was still present in RV appliances?

It's ONLY fault has been that for overall long life it needs to be kept somewhere near level when camping - and until they mount RV propane refrigerators on gimbals (as they should) - this is the only thing that keeps it from being hands-down far superior to a compressor refrigerator's unending energy requirements when drycamping.

For what it's worth, I believe that a somewhat spectacular person from history with a last name of "Einstein" coinvented the gas absorption refrigeration process.

Right. Mr Wiz gets it all done because he has a set-up that will do that. IMO he is still something of a slave to his fridge by having to run the gen/charger more, but in his case it is not onerous as is, so it is all good. He has learned what works for him.

The point has to be-- just be ready to deal with things as they actually are when off grid, with whatever set-up you choose. Choose wrong, and you will soon know it.

A 120v only vs a propane option fridge has an enormous impact on what sort of set-up you need for going off grid. It is a fairly trivial matter if all you do is FHU and a bit of travel down the road between campgrounds with the fridge on at 120v.

i don't bite my nails
we are full time off grid with residential fridge, and over 600w of solar, 665AmpHr battery bank

i don't mind IF i burn a more gas for more genny time

i don't have a mortgage or a rent payment, or stick & brick utilities and taxes

you can
get a couple extra batteries, enjoy their off grid with compressor fridge
then recharge at home

now IF your trying to go OFF grid for extended periods while still juggling other payments, and think charging batteries is expensive or to much trouble
then go ahead and stick with LP fridge

LP does offer the most time for the energy cost
it does NOT offer the best cooling,

In the end the residential frides are fine if you are generally a FHU camper.
They work well enough to allow you to travel from CG to CG.
However if you are a avid boondocker and prefer to camp off the grid. Stick with the LP models unless really want to dedicate a lot of funds an effort to make the rez fridge work effectively.