Dometic fridge-colder on propane than electricity?

Discussion in 'Refrigerators and Coolers' started by packrat1969, Jul 21, 2013.

  1. packrat1969

    packrat1969 New Member

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    Hi,

    This is my first season with a (new to me) 1999 Flagstaff 620, and I am a little curious about some of its inner workings. This pup has a small fridge that can run off of 12VDC, 120VAC, or propane. From what I've read, the 12v option is not usually a good idea as it kills batteries pretty fast. I've used the propane option over several 3-day camping trips and it seemed to work great. Cold within minutes. Almost icing, which I don't mind.
    I've been camping since Friday, and plan to do so until next Friday, so I've been using the 120v option to conserve propane. It seems as if the fridge is not getting as cold as it did with the propane. Granted, it has been 90+ degrees F here, but it literally took the fridge a day and a half to even feel colder than ambient. It's a good thing all the food was packed in a cooler full of ice. Currently the fridge feels cool, but still not as cold as I thought it should be.
    Is this a normal situation? Is it the ambient temps affecting my fridge's cooling ability, or is the 120v operation somehow less efficient than propane?
     
  2. raspivey

    raspivey New Member

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    12V is best only used when travelling with the TV plugged in to keep it charged otherwise, you are correct, it will pull a pretty good amount of battery down. The 12V and 110V settings use the same heating element (these systems boil off a mixture to create pressure instead of a compressor and the evaporation causes the cooling effect) while the propane uses basically a pilot light to do the same thing. Most people will say that the propane works better and I'm inclined to agree with that based on my experience. I wouldn't worry about running it on propane for an entire trip unless you were fairly low...it really doesn't use much propane. As far as the ambient temp...it actually does make a big difference. I can freeze milk in mine if it's below 60 deg. or so. Last week in the upper 90's it had trouble keeping up. The evaporator coils are on the outside with no fan moving air across them for cooling. The hotter the air on them, the less cooling it will do. Search for mods on this one (usually a baffle and a 12V computer case fan or two). I never got around to doing it, but I understand it increases efficiency by 20-40%.
     
  3. tombiasi

    tombiasi Well-Known Member

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    X2 on raspivey's comments. They work best on propane and are quite stingy with it. Unless you will be out for a month or so I wouldn't worry about the propane.

    Tom
     
  4. packrat1969

    packrat1969 New Member

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    Hi,

    Thanks for the quick replies. Yeah, I've wondered about the efficiency of just plain convection cooling inside the side compartment of the camper, and I have heard of people using a 12v case fan or two. Just never got around to it, and anyway the propane seemed to be doing it's job.
    As far as operating on propane for a week, I do have a concern as to how the fridge's propane flue is designed. It's like T fitting, with the upper portion angled for air draw through the flue. This thing was installed right next to structural wood and fiberglass insulation. I can't believe that it hasn't burned down the camper!
    I felt this was an issue, so I custom fitted an angled sheet metal plate to isolate the flammables from the exhaust gasses. Now if I can only figure out why it soots up the inside of the white plastic covers (just the upper corner by the flue). It did this from day one, and is not related to my plate modification....
     
  5. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

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    I run my fridge on propane all the time. It barely sips the stuff. I'm currently on a 5-week trip and have no concerns about propane consumption. Hey, if the cylinder does run out just stop in a town ad refill it.
     
  6. Blue2

    Blue2 I teach them how to light fires, safely.

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    Sooting issues with propane are caused by improper combustion and a lack of oxygen, check for spiderwebs or things limiting oxygen intake, if all clear maybe there is an air adjustment to allow more air in the intake.
     
  7. PhotoMasterGreg

    PhotoMasterGreg New Member

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    Great info on the sooting. I've never seen it, but it is good to be aware of it.
    Thanks Blue2!

    Sent from my SPH-D710 using Tapatalk 4 Beta
     
  8. tcanthonyii

    tcanthonyii Member

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    I experienced this as well this weekend on my first trip. First I thought it wasn't working at all until I realized i had the knob on low cool, doh! Once I figured that out I tested the fridge on both AC and Propane and Propane wins hands down. The fridges barely use propane so I wouldn't worry about it, plus it's cheap.
     
  9. mlong

    mlong New Member

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    I was concerned about propane consumption on my first trip also. After a 6 night trip with no electric I checked my propane tank with a gauge. I was surprised when I saw it was a little less than 3/4 full. We even used the propane quite a bit for cooking as well so the fridge barely used any propane.
     
  10. Mickeyrv

    Mickeyrv Week day camping is great

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    I was told by my dealer that a 4 cu. ft. refrigerator with freezer would run continually on a 20 lb. bottle of propane for up to 6 months. They also told me that when I had a 3.0 cu. ft. rerfrigerator with freezer that the 12 volt would only maintane the inner temperature while towing, and that I should run it on propane when not towing. My 4.0 cu. ft. has 115 a.c. or propane and that the 115 ac. only tries to maintain the internal temp. The propane works best in all situations. Since I only camp about 20 days per year, I refill my propane tank (1 only 20 pound) at the start of each camping season.
     
  11. bmcilravey

    bmcilravey Lovin' the pup!

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    This is really great info. I assumed on a service site that ye ol plug in would be best. Sounds like propane is more efficient. May give it a shot on next trip.
     

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