what is best for the durability of a refrigerator?

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unicornio
unicornio Solar Expert Posts: 217 ✭✭
in Off Grid Solar & Battery Systems #1
hi, there,

i just replaced the thermostat on my chess type (hack frezzer) fridge. I have used a unit of STC-1000 digital control that I bought very cheap in the eastern oriental empire. I recommend this unit to hack freezers to fridges. finely the option to play the original thermostat coarse setting has not worked too well in some cases...I put here some images of it.

Now the refrigerator is operating within the same temperature ranges, but their operating cycles are less durable, more shorter, but starts 10/15 minutes every two hour ... with the old thermostat, the work cycles were much more spaced, but also much more longer.

it is clear that the new sensor has much less thermal inertia, I set to start working with 4ºC and it stops with 2°C, that is, i could increase this margin but the temperature inside may have more variation...

my question is: what will cause more wear on the fridge compressor? long cycles but more spaced in time, or short cycles (ten minutes) every hour and a half or two ... and regarding the efficiency, which will be better?...

many thanks in advance!
good day, mates!
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  • feedhorn
    feedhorn Solar Expert Posts: 103 ✭✭
    #2
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    Re: what is best for the durability of a refrigerator?

    A good thermostat should have an adjustment for Hysteresis so you can limit the short cycling.

    Also if you put the sensing bulb down in the bottom under a large thermal mass it should do the same thing.

    Short cycling uses more power than long runs but not by much.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #3
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    Re: what is best for the durability of a refrigerator?

    good day, mate!
    and many thaks for your post:
    feedhorn wrote: »
    A good thermostat should have an adjustment for Hysteresis so you can limit the short cycling.
    Also if you put the sensing bulb down in the bottom under a large thermal mass it should do the same thing.

    that's what I'm considering, (as the homebrewers do), to put the sensor probe in a water glass (or water bottle), now I have it in the air ...
    (homebrewers really have become gaining a lot of science about temperature control! ... ;-)
    feedhorn wrote: »
    Short cycling uses more power than long runs but not by much.

    you mean the number of starts, which will be higher with short cooling cycles?...
    you mean more energy because more peaks of engine starts?...
    but what you think about the loses for heat?...with longer cycles, the compressor is more heated?...
    the greatest number of starts producing more wear on the engine and compressor? ...

    the thermostat is beautifully designed, and has 4 fields for configuration:
    F1: the temperature is to be maintained, where the compressor turns off (2°C)
    F2: the temperature difference for the compressor working again (2ºC higher, 4°C absolute in this case)
    F3: the delay to protect the compressor from repeated starts (2 minutes)
    F4: Calibration of the thermometer (0,8ºC)
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  • Feenix
    Feenix Registered Users Posts: 16 ✭
    #4
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    Re: what is best for the durability of a refrigerator?

    Hmmmm, interesting idea. This is the controller I have for my hack:

    http://www.amazon.com/Johnson-Controls-Digital-Thermostat-Control/dp/B00368D6JA/ref=sr_1_1?ie=UTF8&qid=1404859223&sr=8-1&keywords=home+brew+controller

    I also currently have the bulb hanging down in the air, a few inches off of the bottom. What would be the benefit to putting in in water? I'm intrigued...
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
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    Re: what is best for the durability of a refrigerator?
    Feenix wrote: »
    Hmmmm, interesting idea. This is the controller I have for my hack:

    http://www.amazon.com/Johnson-Controls-Digital-Thermostat-Control/dp/B00368D6JA/ref=sr_1_1?ie=UTF8&qid=1404859223&sr=8-1&keywords=home+brew+controller

    I also currently have the bulb hanging down in the air, a few inches off of the bottom. What would be the benefit to putting in in water? I'm intrigued...

    The extra mass slows the temperature change of the sensor, reducing 'incidental' cycling.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #6
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    Re: what is best for the durability of a refrigerator?

    My sensor is glued to a piece of lead, which is then insulated. Works great. Runs 5 minutes once an hour and for my situation, a converted ES upright freezer converted to a fridge, it's as perfect as can be.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #7
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    Re: what is best for the durability of a refrigerator?
    Feenix wrote: »
    I also currently have the bulb hanging down in the air, a few inches off of the bottom. What would be the benefit to putting in in water?
    Cariboocoot wrote: »
    The extra mass slows the temperature change of the sensor, reducing 'incidental' cycling.
    waynefromnscanada wrote: »
    My sensor is glued to a piece of lead, which is then insulated.

    My sensor is wrapped in a bit of bubble wrap, but no extra mass. Works great. Mass and insulation are a balancing act... if you use too much of either, you will overshoot your set points by too much and have very wide temperature swings.

    If your thermostatic regulator (such as the Johnson Controls, mentioned by 'Feenix') has adjustable hysteresis, you don't need to add any mass or insulation.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #8
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    Re: what is best for the durability of a refrigerator?

    hi, there,

    thanks so much to all you guys!...

    here is a chart where the duty cycle of the fridge is shown with the new thermostat:
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  • Surfpath
    Surfpath Solar Expert Posts: 463 ✭✭✭
    #9
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    Re: what is best for the durability of a refrigerator?

    Hi Unicornio,
    How is your new converted freezer doing? Any update? Have you measured its Kwh/day consumption?

    ps. Must be warm by you (30 degree C battery temp from your chart above).

    Cheers and best wishes,
    SP
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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  • unicornio
    unicornio Solar Expert Posts: 217 ✭✭
    #10
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    Re: what is best for the durability of a refrigerator?

    hi, Surfpath,

    the battery is located in another unit more than 200m away from the house, where are the equipment of the power plant, and battery temperature is high because it is hot here ... ;-)

    housing, where is the fridge, I have about 28 º C, too much heat ...

    I'll make an average consumption between the last week, it was warm, and this week there are more normal temperatures, and publishes the results on here ...

    so if you've checked with both thermostats is that consumption equals. the original had more inertia and refrigerator cycles were longer but more spaced. with the new thermostat, cycles are shorter but more frequent ...

    however you can see it here if you want:- monitor solar on-line-

    I will use these data to make an estimate of the consumption of the refrigerator.
    I do not have any meter that can measure the exact consumption of the fridge only, I have to buy it ... ;-)

    regards,
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  • Surfpath
    Surfpath Solar Expert Posts: 463 ✭✭✭
    #11
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    Re: what is best for the durability of a refrigerator?

    Good, interesting to see how the fridge works for you. Get those battery temperatures down my man. Cheers,
    SP
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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