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Thread: Finding an inverter compressor fridge with no temp limits for an RV

  1. #1
    Join Date
    Nov 2018
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    Georgia
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    Default Finding an inverter compressor fridge with no temp limits for an RV

    I'm shopping for a residential fridge for my RV, but I do boondock (dry camp) with my solar/batteries/inverter a lot so power consumption is a big concern along with the fridge being rated for patio/garage use (I.E. not having temp limit switches that shut it off outside certain temp ranges) since in an RV it will be exposed to a wide range of temps.

    One of the big reasons for the inverter compressor is that running off batteries it allows it to ramp up slowly and not be such a big hit and doesn't have to run at full blast when it's running. However, I'm having trouble as I search through fridges trying to determine if it has in inverter compressor, or variable frequency compressor, or digital compressor or what every other name they come up with. It doesn't seem well documented nor are the temp cut off switches, but I know both are things to watch for when chatting with others that went residential in an RV.

    Size of the fridge is also a big concern. I'm replacing a Norcold 1210 series (12CF) which is a double door fridge, but RV fridges tend to be very shallow especially with all their absorption type setup taking up the entire backside of the fridge. I'm looking at replacing with a standard freezer over fridge setup since these seem to be smaller in size, use less energy, and can find closest to the size I need. Depth of a fridge is one of my largest limitations, followed by height and width. I have about 23" depth to the wood trim, but I have room to stick out past that hitting anything, however the fridge is in a slide so the further out I am, the less of the fridge that is supported underneath? I think if I keep the case in the 26"-28" depth with the doors a little further out, I'll be okay? Height I have about 63.5" to the wood trim and get can up to about 65.375 if I remove the trim. Width is 33 between the wood trim. 36" wide fridges will not fit. Apartment size fridges help out a lot with the depth and height, so I'm bouncing between those and counter depth ones.

    So far these are a couple models that I checked out physically in a store and think I can make fit size wise.
    Frigidaire 18CF FFTR1814TB or FFTR1821TB. The main difference I see between these two is the shelving (wired vs glass) and an extra drawer in the fridge. Otherwise they appear pretty close even having the same KwH rating.

    GE 15.5CF GTE16DTHBB. This one would fit in height wise with almost no modification is a bit shallower than the one above. However glancing through the manual I saw a blurb that it doesn't run as efficient under 60 degrees and could find nothing about the compressor?

    When looking Frigidaire models on their website for like the FFTR1821TB, I do see that under specs it list "Condenser Type: Dynamic?" Is that the same as a inverter generator or something else? The reason I'm confused though as a fridge that came up in RV pages with a variable frequency drive compressor that is very easy to run on batteries is FFTR1222QB from a couple years ago that is apartment size, yet under specs it says condenser type: Static? So that confused me?

    Thanks for any help in this matter.
    Last edited by BlueLghtning; November 19th, 2018 at 11:19 AM.

  2. #2
    Join Date
    Oct 2004
    Location
    Canada
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    Unhappy

    "Condenser Type: Dynamic?" Is that the same as a inverter generator or something else?
    I have no idea why they call it "dynamic", it appears to be a regular "forced air condenser".

    under specs it says condenser type: Static?
    "Static" means it does not use a fan, either the condenser coils are up the rear of the refrigerator (see pic below) or they built into the side of the cabinet in which case they'll need 'beating room' around it when installed or it won't cool properly.

    Rear condenser example
    Click image for larger version. 

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    It's very unusual to find a refrigerator that uses an invertor and/or variable speed compressor except very large (and expensive) ones, or very small ones. FFTR1222QB is a only 12 cu.ft and isn't an invertor model either!


    BTW. Most domestic refrigerators will have a problem if subjected to below freezing temperatures.

    JMO

    Dan O.

  3. #3
    Join Date
    Nov 2018
    Location
    Georgia
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    Default

    Thanks for the helpful info. Yeah in the store they were telling me you only find the inverter ones on the much more expensive units. So the FFTR1222QB isn't an inverter type? How did you come to that conclusion? Just because it's a small 12CF fridge?

    This is what the owner on an RV forum who usually goes into way too technical detail on his post wrote. He calls it Variable Frequency Drive. Is that different than in inverter compressor or same concept?

    We are amazed how little power our soft-start VFD (Variable Frequency Drive) Fridge uses, The unit model it is: Frigidaire, Mode:l FFT1222QB
    We converted to a 12 Cu ft VFD shop / patio model VFD (Variable Freq Drive) fridge almost two years ago. The solid-state VFD in this fridge makes this unit insanely efficient power-wise.


    We have boon docked many times more than two-weeks solid with only two group 31 deep cycles and a cheap modified 400W inverter driving the fridge and our coffee grinder and still never had any issues.

    The real advantage of the VFD is that it NEVER starts the fridge compressor at full speed and almost never runs the compressor at full rated power often the entire on-time for a 24 hour period is measured in minutes of low-speed / low load compressor operation ONLY as needed to maintain the desired temps.

    "Normal Fridges" are like hot-rod teens that peel-off at every stop light ...... most fridges start at "Full-Throttle" and thats a HUGE waste of power.

    Be careful when selecting a new residential fridge for RV use.....many new fridges only operate at a limited ambiant temp range of about 60f to 85f and then a internal kill-switch powers them off ........ this is a ploy to better energy-star ratings
    In another post, he wrote this about the same fridge
    Make: Frigidaire
    Model: FFTR1222QB
    Max Load (running): 0.8 to 1.5

    My motor geek friend played with the fridge with his Flukescope and measured insanely low current runs with very low compressor runs and vast periods no elec use at all....
    He left the Flukescope on the fridge for a couple days and when he played the traces back it was amazing how tiny the current use was.....way below the max listed and it was hot and we opened the door a lot....

    Chuck contends that the normal FULL throttle starts and FULL speed compressor runs have been robbing fridge owners since the first fridge was sold...
    I did find this wiring diagram to the 1222QB model the other guy chats about. Those .8 to 1.5 amps come right from it? I'm not sure where he saw VFD in this or figured out it had it if it really does? - ftp://ftp.electrolux-na.com/ProdInfo.../242301700.pdf

    Here's the one for the 1821 model I listed above. It's a little larger at 18CF compared to 12CF so you would expect it to use more power, but it's listed at 1.1 - 1.6 amps which isn't bad at all. ftp://ftp.electrolux-na.com/ProdInfo.../241588207.pdf

    Just trying to learn more to make in an informed decision. Thanks!

  4. #4
    Join Date
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    Canada
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    Default

    So the FFTR1222QB isn't an inverter type? How did you come to that conclusion?
    I looked at the wiring diagram. It plugs into a 115v outlet and power goes directly to the compressor, no inverter in between.

    Click image for larger version. 

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    Maybe he plugged it into an external inverter? I don't know. You'll have to ask him.

    you would expect it to use more power, but it's listed at 1.1 - 1.6 amps which isn't bad at all.
    Running amps of most domestic compressors will be in that same general area 1-2 amps. Starting amps can be much higher.

    Frost free models also have a 600-800 watt defrost heater that comes on periodically when it goes into defrost. I don't know how that affects consumption.

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