Refrigerator on propane or electric?

[TomG2]

I know the comparisons of furnace versus catalytic versus electric space heaters has been asked and answered many times, but I can't find one on refrigerators. Right now, I am using about 10 kwh per day for the refrigerator in 90 degree South Texas weather. Any idea what the equivalent propane consumption would be?

[MEXICOWANDERER]

Paid for electricity is best unless ambient temps rise to the point where use of LPG is mandatory. My crystal ball does not reveal how much trouble it is for you to refuel. In my scenario
I was trapped. Diesel was .15 a gallon LPG was about .30 but it was the expense of refueling that was a no win. I had to move the rig to refuel LPG while I could transport 3 55-gallon drums in the pickup. That skewed the calculation. Diesel and genset won. A gallon of diesel translated to combustion and mechanical motion then to electromagnetics for electricity which then powers a nichrome resistance unit to produce heat is a long equation. Combusting LPG to make heat is infinitely less complex. How much each kWh costs is THE deciding factor. Hypothesi is always trumped by reality. You have the answer to this at your fingertip.

[TomG2]

Put a price on it. I don't see the return on investment for enough solar to run my refrigerator since I am only using about $1.00/day to keep my food cool. I guess my question should have been Park Electricity, Solar, or Propane for running a RV refrigerator.

[pianotuna]

And I gave you a solution where you can run the fridge without paying for electricity.

-30-

[TomG2]

I repeat, I am only interested in whether it is practical to run a Dometic RV refrigerator on propane instead of park electricity. Investing a large amount of money in solar is of no interest. For one thing, I am parked under a large carport which means that the solar would have to be portable or remote. Not what I want to do.

I have been monitoring temperatures and they remain consistent at 39-40 F whichever energy source is being used.

[pianotuna]

Hi TomG,

With respect, your thread was about the fridge.

At this moment I'm "forcing" the load support feature on my Magnum 3000 hybrid inverter to support the voltage to my air conditioner and fridge. That means my (modest) solar system is providing about 175 watts. The total use is between 1500 and 1600 watts. I'm not doing that to save the park money (electric is included in site rental), I'm doing it to protect my air conditioner. As a side benefit, it is cheaper for me to run the fridge from the park power, than to run on propane.

If I so wished I could (and have done in the past) run my roof air and fridge from the inverter/battery bank. I can do that for about 2 hours. However, then I would be at the mercy of the (old, tired) electrical system at the park, unless I was willing to drop below 50% state of charge on the battery bank.

Running the roof air is quite possible. 1600 watts of solar, a 48 volt LI battery bank (200 amp-hours @ 48 volts), a dc 48 volt to dc 12 volt converter for house loads, a Magnum 4048 hybrid inverter, and a PT-100 Magnum solar charge controller. Of course, with that sort of system one would abandon the propane fridge, and get a nice residential unit instead. Funnily enough, the cheapest part of doing so is the cost of the panels.

TomG2 wrote:

pianotuna wrote:
Well if you don't want to "pay the park" you could always add a solar system. It is the nearest thing to a free lunch that one can find.

The investment in solar large enough to run my air conditioner twenty hours a day would be pretty large. More than I want to make.

[Almot]

0.3-0.5 gal or 1.5-2 lbs of propane a day, for a fridge. More-less.

Your 8 or 10 KWH for fridge is abnormally high.

[MEXICOWANDERER]

The BTU DIFFERENTIAL between gas and electric "Says It All" including foot notes and end notes. When an individual is parked 1,600 miles from the US border and running a diesel genset day and night, it is tempting to TRY using an AC heater, rather than driving 116 miles back and forth to Chetumal Q.R. for butane fill ups. My orifice attempts were done on .001 increments. The VELOCITY increase of gas using the original orifice but tweaking the regulator using a manometer revealed a better temperature control of the contents of the refrigerator. Try using 127 vac power down here in the tropics and you will be food poisoned within five days. UNIFORMITY of test results in relationship to a set goal were what you were after. My goal was to keep food from killing me. FOUR REFRIGERATORS Dometic and Norcold (three attempts were new units), plus a full shade palmetto "enramada" were used to try and keep food storage in a safe zone. This was in August of 1988 and hurricane Gilberto disrupted my plan to stay and keep skin diving the Chinchorro reef. I moved out to the Xalak peninsula from the Chetumal beachside RV facility and everyone there was complaining of spoiled food, so they gave up and started eating out. RV gas absorbsion refrigeration has it's limitations and it . does . not . work . well in the tropics. Or do you think it was FUN spending three thousand dollars twenty five years ago for 24 refrigerator and separate freezer. Sheesh! Sal, and crew, at KOOL FUN Irwindale California, sold and rebuilt on site THOUSANDS of cooling units. Yeah he rebuilt the absorbsion units himself, declared non commercial gas absorbsion (meaning RV) to be (and read this carefully) INADEQUATE to maintain food safety in the hot tropics. Not SUB tropics - the real McCoy. I have NEVER experienced this issue with freon units. And nine out of 10 guests in my old RV park complained about food going bad in the door shelves, with NORMAL VOLTAGE supply. They were not happy to have to switch to gas (which helped greatly) but the nearest gas plant was and is at Guacamayas, a 36 mile drive each way.

How much "experience" does a person need to STATE what i just STATED? 🙂

[MrWizard]

here is what i used to go by, and the advice I offer

check you AC voltage reading in the hot afternoon with the A/C on and the fridge ON and Everbody else in the park is home and doing the same thing
also check the temp inside the fridge

if you have 115v and the fridge is properly cold
go ahead use electric if you want
my preference was always use LP,
it provides the same heat to the system and the same amount of fridge cooling 'all the time' no matter what the electric voltage is
the few cents difference in LP or electric, the LP dealer or the park
mean nothing to me, i want that fridge cold
and if voltage is low, and its hot outside, the LP will make it colder than electric

like i said 'i used to do'
we have a 120v residential compressor fridge, now.. no choice but electric, but it only needs 100w not 325w
and we make our own electricity

[RV_Sam]

pianotuna wrote:
Hi Tom,

It is nearly impossible to use 10 KWH for just the fridge. They commonly draw 325 watts. That would 7.8 KWH per day if it never cycled. Are you running the seal heater? If so turn it off.

"That would 7.8 KWH per day if it never cycled."
Is this for sure fact ? If so answers what I have been working on? Thanks.

[dougrainer]

MEXICOWANDERER wrote:
4.4 lbs per gallon. A 20 pound pot is filled to 85. Better refactor your calculations. Check OPD valve data. Four gallons and small change for fourteen dollars. I've never encountered an RV refrigerator that cooled as good on electricity any electricity than it did on LPG. I even tried tweaking my regulator to 13" water column which helped a little on gas. Electricity cooled new Nor-cools to the low 60's while gas minimums were high forties, low fifties.

Drilling out burner orifices was a waste of time. Overheated the burner chamber.

The reason you believe this is because you do NOT have the experience to state what you stated. ALL my tests when fixing refers(thousands over 37 years) is based on 120 operation. The only time I test on LP is if the customer has a specific complaint on LP. You may be an electronics genius, but NOT a refer expert. Your last sentence tells it all. Doug

[MEXICOWANDERER]

4.4 lbs per gallon. A 20 pound pot is filled to 85%. Better refactor your calculations. Check OPD valve data. Four gallons and small change for fourteen dollars. I've never encountered an RV refrigerator that cooled as good on electricity any electricity than it did on LPG. I even tried tweaking my regulator to 13" water column which helped a little on gas. Electricity cooled new Nor-cools to the low 60's while gas minimums were high forties, low fifties.

Drilling out burner orifices was a waste of time. Overheated the burner chamber.

[TomG2]

dougrainer wrote:

What IS the cost of LP that they deliver? They do NOT deliver a cheaper price LP than if you purchase at their store location. Now, if you have a motorhome, then having them fill at your site is going to be cheaper than going to them. Doug

Twenty pound bottles ARE $14 delivered or $12 PICKED UP. I DON'T worry about the extra $2.

[TomG2]

pianotuna wrote:
Well if you don't want to "pay the park" you could always add a solar system. It is the nearest thing to a free lunch that one can find.

The investment in solar large enough to run my air conditioner twenty hours a day would be pretty large. More than I want to make.

[pianotuna]

Well if you don't want to "pay the park" you could always add a solar system. It is the nearest thing to a free lunch that one can find.