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?

[time2roll]

TomG2 wrote:
All of this is in 95 degree weather.

Assuming this is a 30 amp RV running the air conditioner all day... I would definitely have the fridge and water on propane only.

[dougrainer]

DrewE wrote:

TomG2 wrote:

pianotuna wrote:
1 Gallon of Propane = 27 kWh (Kilowatt Hours) of electricity.
.....snip.....

So, if I pay less than $4.19/gallon (27 X $0.155/kwh) for propane, I am coming out ahead? Again, I know that I will not be saving hundreds of dollars, just not giving it to the park for electricity.

You do have to know the relative efficiency of the fridge on electric vs. propane. I would guess that somewhat more heat is lost from the propane (i.e. not transferred to the ammonia in the cooling system) than with electric, though I don't know that absolutely.

Otherwise, the math is correct. If you're actually paying, say, $2.19 a gallon for propane, then propane would undoubtedly be cheaper in your case. Your savings in that case could amount to almost $.50 per day.

The BTU of LP and 120 is so close as you cannot really measure it. Now, one thing that RV refers have a problem with in hot weather is the LINE voltage at some Campgrounds. The lower the line voltage from 120 volts the less the refer will cool correctly on 120 volts. If the line voltage drops below 115 volts, I would advise to switch to LP until the line voltage rises. Doug

[dougrainer]

TomG2 wrote:
I can do the math and I am as lazy as the next guy, but I don't like paying the park $0.155/kwh for electricity. Besides, the propane guy delivers right to the door. I have to purchase propane anyway since that is all my water heater uses. Sounds like I better get a more accurate reading on the electrical usage.

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

[DrewE]

TomG2 wrote:

pianotuna wrote:
1 Gallon of Propane = 27 kWh (Kilowatt Hours) of electricity.
.....snip.....

So, if I pay less than $4.19/gallon (27 X $0.155/kwh) for propane, I am coming out ahead? Again, I know that I will not be saving hundreds of dollars, just not giving it to the park for electricity.

You do have to know the relative efficiency of the fridge on electric vs. propane. I would guess that somewhat more heat is lost from the propane (i.e. not transferred to the ammonia in the cooling system) than with electric, though I don't know that absolutely.

Otherwise, the math is correct. If you're actually paying, say, $2.19 a gallon for propane, then propane would undoubtedly be cheaper in your case. Your savings in that case could amount to almost $.50 per day.

[TomG2]

pianotuna wrote:
1 Gallon of Propane = 27 kWh (Kilowatt Hours) of electricity.
.....snip.....

So, if I pay less than $4.19/gallon (27 X $0.155/kwh) for propane, I am coming out ahead? Again, I know that I will not be saving hundreds of dollars, just not giving it to the park for electricity.

[TomG2]

I can do the math and I am as lazy as the next guy, but I don't like paying the park $0.155/kwh for electricity. Besides, the propane guy delivers right to the door. I have to purchase propane anyway since that is all my water heater uses. Sounds like I better get a more accurate reading on the electrical usage.

[dougrainer]

valhalla360 wrote:
Check your fridge, our heater element is only 180w

Also factor in the hassle of replacing the tank every couple weeks if running on propane.

Love the ability to have the fridge run when off the grid but once plugged in, so much easier to just use the electric.

People NEVER factor in the cost of going to get the LP tanks refilled. NOT the cost of the LP, but the cost in gasoline of driving your vehicle to the LP store and back. THAT negates any supposed cost savings on electricity. IF the RV CG offers LP, THAT LP is usually higher in cost than the local LP store, just like Marina Fuel for boats cost more. Doug

[valhalla360]

Check your fridge, our heater element is only 180w

Also factor in the hassle of replacing the tank every couple weeks if running on propane.

Love the ability to have the fridge run when off the grid but once plugged in, so much easier to just use the electric.

[TomG2]

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.

I admit that I rounded up with the estimate. I am using about 28 kwh per day with the refr on electric and about 21 kwh per day on propane. All of this is in 95 degree weather.

Thanks for the conversion formulas.

[pianotuna]

1 Gallon of Propane = 27 kWh (Kilowatt Hours) of electricity - This means that one gallon of propane contains the same amount of usable energy as 27 Kilowatt Hours. Or we can say that 27 kWh equals approximately 91,500 BTU.

A 100 watt light bulb left on for a full day (24 hours) will consume 2.4 kWh. If propane were to power the same light bulb (hypothetically- remember, we're comparing energy content) for 24 hours, it would use .09 gallons of propane.

So to scale that up, multiply by 4 to get approximately the 10 KWH.

i.e. 0.09 x 4 = 0.36 gallons of propane per day.

http://www.propane101.com/propanevselectricity.htm

[pianotuna]

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.

[2oldman]

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