An idea to save electricity and have some modern conveniences

Discussion in 'Energy & Electricity' started by townparkradio, Sep 8, 2010.

  1. townparkradio

    townparkradio Family Friendly DJ

    I have a theory.. this was originally going to be a rig as a gift to my wife's parents, but I want to talk about it first to bounce my idea off of others.

    We all know heat rises and condensation tends to pool, correct? I present to you, a way to get a working fridge for a fraction of the cost involved normally. Your average drop down freezer is actually rather energy efficient... moreso than a fridge would be at the same temperatures. As I understand it, you want your average fridge to be around 36 degrees. I've owned decently sizable freezers before, and had noted they reach that temperature within a few minute of having been turned on, regardless of ambient temperature. It also holds it's frozen temperature fairly easily, if you're an idiot and leave the top open. A vertical freezer, not so much. So.. this tells me if you're living off the grid.. you should never be using a vertical fridge.. period. Secondly, it gave me this idea.

    A simple thermostat relay inside the drop down freezer with the power cutoff at 36 degrees or below should actually turn the freezer into an INCREDIBLY efficient fridge. My only issue is that, for the life of me, I cannot devise a schematic to prepare such a thermo with a cutoff relay. There are some market solutions you'd think, but those are all made to turn a unit ON when a certain low temp is reached. As I understand it, this should draw like.. a few watts a DAY provided you don't leave it open for long. Drop down is inconvenient for a fridge but let's not kid ourselves... if you're willing to live off the grid you're already willing to give up things like "staring at the fridge and picking food out of it".

    Anyone got any ideas here? The makeup of a thermostatic relay like this is beyond my skills... but then I'm probably doing it wrong anyway.. I'm fiddling with resistors and a copper strip and really it's a stupid way to attack the problem.
  2. nj_m715


    There's a yahoo group that's all about turning chest freezers into fridges. Most of them use a beer brewing t-stat to control the temp, but there are other options. They're into other energy saving things like super insulating the unit and using root cellars.
    RefrigeratorAlternatives : RefrigeratorAlternatives

  3. townparkradio

    townparkradio Family Friendly DJ

    Well, as they say, everything you think of has been thought of before... but that's no reason for me to give up innovating. Thank you for the link, it gave me a lot of information.
  4. Tirediron

    Tirediron RockyMountainCanadian

    The chest freezer to fridge is a very good idea, but watch out for super insulating, the condensercore is along the outside of the freezer's metal enclosure and MUST get rid of heat , refridgeration is all heat pumping and the heat pumped from the area that is cooled needs to be exchanged with "room air" (I didn't watch the videos in the link maybe they mentioned this already
  5. gypsysue

    gypsysue The wanderer

    We read somewhere a couple years ago that you shouldn't put insulation on a fridge, but of course I can't remember why it said not to!

    TPR, that's actually a brilliant idea, your freezer-to-fridge plan. I'd have never thought of it! Your in-laws are lucky to have a smart and helpful son-in-law like you!
  6. ZoomZoom

    ZoomZoom Rookie Prepper

    All I can do is pile on and say it's done regularly by home brewers. I have a couple friends that did exactly that. IIRC, the conversion part is about $20 and takes 15 minutes to install it.
  7. Tirediron

    Tirediron RockyMountainCanadian

    Didn't I just answer why not to add insulation? , the condenser needs to get rid of heat, if you insulate the outside of a freezer the heat removed from the interior (the now cold part) has no where to go and the freezer becomes LESS efficient because the compressor runs for more time trying to cool :scratch
  8. ZoomZoom

    ZoomZoom Rookie Prepper

    Who said to add insulation? Every post I quickly re-read agreed with you.
  9. nj_m715


    I said it, but I thought it goes without saying (guess I was wrong) that you do not insulate the condenser coil or the compressor. You insulate the rest of the unit to keep the cool air in. Some guys used foam boards or even just an old blanket.

    Sue, All units come from the factory with some insulation, you just add a little more.

    Cleaning the coil to allow for max heat transfer helps a lot too. When the last time you guys pulled out your fridge to the back and bottom? Make sure your door seal is in good shape.
    Last edited: Sep 8, 2010
  10. gypsysue

    gypsysue The wanderer

    Yeah, I knew not to insulate around the condensor. Our fridge is a 2-year old frost-free, and it has a smooth back, with the motor "stuff" at the bottom, underneath, open to the back. We keep the motor area clean.

    As for insulating the side walls and top...I never could figure out why that would be a problem. I guess it wouldn't be. We have plenty of that 1" styrofoam sheet insulation leftover from another project. Might give it a try.
  11. townparkradio

    townparkradio Family Friendly DJ

    Misread. Never mind.
    Last edited: Sep 9, 2010
  12. gypsysue

    gypsysue The wanderer

    Sorry, TPR, I guess we kind of side-tracked your thread.

    I hope you can find a way to make a thermostat that would do that -- shut down at the right temperature. Surely someone on here knows something about this? Where's JeepHammer when we need him, he seems to be the go-to guy for a lot of things! Smart guy.

    Anyway, I thought this was a good idea.
  13. Emerald

    Emerald Well-Known Member

    I've been dreaming of redoing my kitchen for years so I do read many things about remodeling and watching all those kitchen redo shows and they now have small fridges that are just drawers that can be built into your cabinets. They are supposed to be very energy efficient not only due to no loss of cold air falling to the floor-and by the fact that most are used for sodas and stuff that your kids tend to just open and close that big fridge for anyways. So it keeps the big upright fridge closed more.

    But if you had small fridge needs and lived off the grid then having maybe just two or maybe three of these small drawer fridges might be the way to go.. But last I looked they were EXPENSIVE!:gaah:
  14. gypsysue

    gypsysue The wanderer

    When we bought the electric fridge we use with our off-grid solar panel array, we went to Home Depot and looked at the watt rating on every fridge. It was interesting to us to discover that a 10-cf frost-free fridge/freezer uses about the same amount of electricity as the smaller "college" fridges. Over that size the watt draw was much higher. The big fridges were way up there.

    We bought the 10-cf one and have used it with our solar panels for 3 years. Long cloudy spells in winter (short daylight hours) are a strain on the solar power, but we simply turn it off if the weather is cold enough anyway (it's on a covered porch on the north side of our cabin).

    I wonder what the watt rating is on those drawer-type fridges? I'll have to search that! Thanks, Emerald, for the information. It's great to hear about new products.
  15. Tirediron

    Tirediron RockyMountainCanadian

    bczoom, I misread you answer, thought you said pile it (insulation on )
    And I was reffering to just freezers when adding insulation, because a lot of them have condenser plates next to the skin on all 4 sides.
    The chest freezer to fridge conversion is done often and can be super efficient,but maybe not all that conveinient

    A stand up fridge could be inproved by adding an internal half door in the bottom to keep the cold from cascading out every time the door is opened
    you would just have to keep the most used stuff on the top shelves,and watch for freezing on the bottom shelves :flower:
  16. nj_m715


    Speaking of the frost free models, you can disable the feature and gain a lot of savings. In order to be frost free they have a little heater inside to switch on every now and then to melt the ice. The heater takes energy to run and forces the fridge to work that much harder. Being frost free is more convenient but it comes at a price.
    I plan on unplugging my heater next time I clean out the fridge. Once or twice a year I like to use up as much of the food and drink in the fridge as possible. I put what's left in my little electric coleman cooler and scrub down the fridge inside and out. My cleaning should be enough time for any frost to melt. When I was a kid my parents had a deep freezer that needed to be defrosted once a year. I don't see why it wouldn't for me.

    This thread's not really high jacked. We're talking about saving electric and I pointed him to the right place for the conversion parts in the first reply.
    Last edited: Sep 9, 2010
  17. JeepHammer

    JeepHammer Well-Known Member

    I did 2 things to make my freezer more efficient.

    Can't go wrong with more insulation!
    Keeping the cold IN, and the heat OUT is the objective...
    Insulation helps with that.

    2. Vented the compressor heat outside.
    Since the freezer sets on the back porch, and the other one is in the shop,
    I vented the compressor away from the freezer so it doesn't have to fight it's own heat.

    If your freezer is in your home, you probably won't have that option unless you install ducting to take the compressor heat out of the building.


    If you shut off the power to the freezer at 32°F. The internal temp WILL NOT be maintained, and you WILL get freezer burn or ruined supplies.
    Virtually ALL freezers will turn themselves off when internal temps reach that point. No need for external thermometers.
    If you can't maintain at LEAST -10°F. then the 'Freezing' isn't complete, and meat in particular will spoil right there in the freezer.


    What WILL save you money in the long run is to install OVERSIZE wire to the unit,
    At least 10Ga. for a 110 volt unit,
    And at least 8Ga. for a 220 volt unit.
    Freezers should have their OWN breakers and 'Emergency' lines if you have a generator or produce your own back up or primary power!

    Cut the plugs off and HARD WIRE the units to the service line.
    Plugs create a LOT of resistance, resistance (Small wire, faulty or too small of contacts in the plugs) will waste electrical current in the form of heat.

    Most people argue with me on this until I whip out the infrared heat gun and show them the 'Glow' from the excessive heat build up...
    Then I compare heat over ambient to the losses to produce that heat,
    Then figure in the energy losses @ the cost of the electricity...

    Pretty soon they are wanting to up-size the wire and hard wire to get rid of those losses (and potential fire staring points!) and that's ALWAYS a good thing!
    Heating up wire/plugs doesn't NOTHING but waste your electricity, and since you don't move the unit (except for cleaning) for YEARS, there is no reason NOT to do it!


    Making sure your unit is CLEANED at least 4 times a year (Dust bunnies, lint accumulation, general crud on the external coils) will reduce efficiency by up to 40% in less than a year.
    Make sure you keep the crud blown out of them, and keep the coils on the back/underside CLEAN with soap and water.

    Generally, small freezers don't have large enough coils to be really efficient, so if you are looking,
    Look for 'External' compressor units,
    Like your home A/C unit,
    Where the compressor heat and hot coils are outside the home,
    Then you don't have the heat in the home to start with,
    And the coils are MUCH easier to clean that way...


    If you know a HVAC guy, ask about moving the compressor outside on the 'Home Consumer' units...
    (he'll probably look at you like you are retarded at first, but once he figures the heat generation in the home, he'll figure it out pretty quick)
    This will save you a lot of money trying to cool the home from the heat produced by the fridge/freezer, and make your system more efficient at the same time.

    Picking up EXTERNAL compressors is always a good thing, and you will be surprised how cheap they will go for when the building is being remodeled or replaced with bigger building!
    You CAN run your fridge/freezer off a 'Split' or 'External' compressor just fine,
    It just takes some plumbing and wiring for sensors, and there really isn't much to it...
    Makes that favorite freezer useful again when the compressor goes out and costs more to replace that little, inefficient compressor than the fridge/freezer is worth...
    Hook it up to a split system, and you are back in business and half the cost!
    And you can run MORE THAN ONE appliance off a compressor, that's not an issue...

    Split systems also give you the option to add a diesel, gasoline or propane/natural gas 'Hot Box' to power up the house with a generator and use the internal combustion engine to turn the refrigerant pump for cooling without taxing your electrical reserves in an emergency situation.

    Big truck 'Hot Boxes' or 'APU' units work GREAT for this, and usually come with the valving for the auxiliary A/C or Refrigeration unit and hot water, electricity all built into one unit...
    Since they are used in EVERY big truck salvage yard,
    And they are EVERYWHERE used/rebuild on the internet,
    They are a VERY good choice for 'Emergency' power, refrigeration, hot water.
    (Water cooled units only will do hot water)

    Remember, every internal combustion engine WASTES at least 85% of it's fuel making HEAT, so no reason NOT to harness that for hot water while you are at it!

    Might as well use MORE of the fuel you are putting into your backup system and getting something for it!


    I'm looking into using that waste heat from the 'Hot' coils in my refrigeration units to preheat water in my home under normal conditions.
    Every refrigeration unit produces a LOT of heat, and that heat is shed to atmosphere, no matter if it's in doors or outdoors...

    'Wet' heat exchanger (inter-cooler) will make the compressor MUCH more economical, plus I salvage the heat produced for preheating water for the system.
    (Closed loop)

    Outdoor compressor 'Split Systems' are used in all commercial applications,
    From convenience stores to factories, and they are MUCH more economical to operate,
    But they are also more expensive when you purchase/install.
    Since the fans, coils, ect. can be MUCH larger, they are more efficient than the little units the stick UNDER the 'Consumer' units where it's all packaged up in a very compact space.


    If you still want an 'Industrial' thermostat to shut things down,
    You are looking for the heavy duty ones...
    You can get the ones from 'China' but they never live,
    You are looking at around $65 to $120 for a good one,
    Honeywell and White-Rodgers are the ones I use most in the shop, ect.

    This is what they look like, and there are two kinds.
    The 'Room' type that has the capillary tube sticking out the top for ambient room temp,
    And the kind with 'Bulb' at the end of a capillary tube for 'Remote' temp control, so you can stick the probe in the freezer or what ever.




    Probe type,



    I DO NOT recommend this for a Freezer since this will keep the unit from reaching the -10°F. or colder needed for keeping things SOLIDLY frozen...
  18. mosquitomountainman

    mosquitomountainman I invented the internet. :rofl:

    A lot of the newer refrigerators have the condensor coils next to the outer skin also. In those cases adding insuation to the outside of the fridge will do more harm than good.
  19. gypsysue

    gypsysue The wanderer

    Thanks, Jeep, for all the info. Great information.
  20. JeepHammer

    JeepHammer Well-Known Member

    Yes, it depends on the model and design,
    If you see the coils on the back, insulation BEHIND them, between coils and fridge is good,
    but if you don't have exposed coils, then don't insulate the back,
    Top and sides are usually fine.

    If you can bend those condensation coils out where they get open air without cracking the lines, that's always a good thing.
    We have about 2 feet behind our fridge, so I bent them out about 20 degrees or so and braced them away from the extra insulation, and that seemed to help also.
    A low consumption fan back there that kicked on with the compressor would add efficiency, but I haven't got around to that yet...

    When we went off grid, we went for a super efficient model ($$$!).
    Standard 'Large' outside, but smaller inside with 'Zones'.
    Smaller inside means more insulation space,
    And we looked for one with coils exposed on the back.
    Many of the new ones have the coils on the bottom, and heat rises, so that's not real good.

    Some blue board insulation between coils and cabinet didn't cost but a few bucks, and with the temp gun, the cabinet stays room temp instead of being cool, so it's got a bunch of GOOD insulation around the internal box.
    Doesn't run very often, but we make a point of keeping the door CLOSED until we figure out what we want...

    We keep the freezer on the back porch...
    Porches are less tax dollars than internal space,
    The freezer doesn't exhaust heat into the house (Which wouldn't be bad if you lived where it was Cold more than too warm)
    So we save on the A/C energy in the summer.

    Next time I do a fridge, it's going to be a split system with compressor in the utility room or outside.
    I'm fiddling with recovering that heat from the condensation coils, but don't have anything off the drawing board yet...
    I'm trying to figure out how to plumb it into the preheat tank, but I'm not a big HVAC guy...
    I'll probably steal the design from an up and running system...
    I know a good idea when I steal it! :p
    Last edited: Sep 9, 2010