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Thread: How much electricity is being used by old inefficient or faulty appliances?

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    How much electricity is being used by old inefficient or faulty appliances?

    I bought a plug-in energy meter which measures and records how many watts, kWh, etc are being used by an appliance.

    I measured a year 2000 freezer that is chewing more than 3 kWh a day. I think the thermostat may have gone but it's going to be replaced with something newer and more efficient that should use a third of the power real world (or a quarter if you go by the technical specifications).

    At current electrical prices the payback period will be about 2 and half years and factoring in increasing prices that will drop to two years.

    Is anyone measuring the usage of their appliances?

    How much electricity are some of your appliances using and costing you?

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    Diamond Member AndyD's Avatar
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    You get lies, you get damn lies then you get technical specifications

    The only way a new chest freezer will be significantly more economical than an old chest freezer is if the insulation is better. If your existing chest freezer has a door gasket in good condition and the lid closes properly then I doubt very much a new one will pay for itself in power saving in under 5 years. If your existing freezer is running 24 hrs a day or the internal temperature is much less than -18C then replace the thermostat, it's a R150 item and takes 5 minutes to replace (if the freezer is defrosted and at room temperature). If your freezer is in a very warm room or gets direct sunlight then you'll save money by moving it somewhere cooler and in the shade. Another thing that radically increases the power consumption of refrigeration units in general is the efficiency of the condensor. If the condensor is blocked with dust or doesn't have sufficient air flow through it and around it then it can increase power consumption of a fridge unit by more than double.
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    Quote Originally Posted by AndyD View Post
    You get lies, you get damn lies then you get technical specifications .
    Until I personally verify them, nothing but a guideline.

    Lets not even get into MTBF!!
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    I am not even gona get involved in this one. What i will say however, if you install led lamps to save electricity or fit a timer to a geyser, but your maid is running your tumble drier for 8 hours a day instead of hanging clothes out to dry, dont expect to see a reduction in your electricity account.

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    Diamond Member AndyD's Avatar
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    Quote Originally Posted by nkawit View Post
    ..........Lets not even get into MTBF!!
    MTBF (mean time between failures) is like MTBLO (mean time between leg over), there are many factors that can affect both of them, some of which we can improve..... some of which we can't
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    Quote Originally Posted by AndyD View Post
    You get lies, you get damn lies then you get technical specifications
    Agreed and I'm assuming it will use more than the technical specifications so I estimated a consumption that is a third more than stated. I will of course measure the actual usage of the new freezer and can post it here if anyone is curious. Bearing in mind that these will be worst case numbers i.e. initial startup and summer temperatures.

    Quote Originally Posted by AndyD View Post
    The only way a new chest freezer will be significantly more economical than an old chest freezer is if the insulation is better.
    Yes, better (more efficient and / or thicker) insulation (including door gasket) is the main way to improve efficiency for a given design although more efficient motors and lights can help. I'm still on the fence with regards to different refrigerants.

    Quote Originally Posted by AndyD View Post
    If your existing chest freezer has a door gasket in good condition and the lid closes properly then I doubt very much a new one will pay for itself in power saving in under 5 years.
    The existing upright freezer is being replaced with a chest freezer so the design change helps (cold air doesn't fall out). The gasket seems in good nick but the door has gotten stuck open a couple of times over the years. Although even when closed 100% it runs 24/7 which brings me to your next point.

    Quote Originally Posted by AndyD View Post
    If your existing freezer is running 24 hrs a day or the internal temperature is much less than -18C then replace the thermostat, it's a R150 item and takes 5 minutes to replace (if the freezer is defrosted and at room temperature).
    This I'll look into once I have the new freezer arrives (it was bought yesterday before seeing your post). An earlier internet search on the make and model number did not yield any results from which I assumed 12+ years is a bit old for a freezer. I'd have to try and source a replacement part once I know what the current thermostat is.

    Quote Originally Posted by AndyD View Post
    If your freezer is in a very warm room or gets direct sunlight then you'll save money by moving it somewhere cooler and in the shade. Another thing that radically increases the power consumption of refrigeration units in general is the efficiency of the condensor. If the condensor is blocked with dust or doesn't have sufficient air flow through it and around it then it can increase power consumption of a fridge unit by more than double.
    Agreed. This one lives in a garage which certainly gets warm in the summer. At least the condenser coils are kept clean and it's against the south face side which doesn't get any sun. :-)

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    Diamond Member AndyD's Avatar
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    Different refrigerants can improve efficiency but in the case of a domestic freezer it wouldn't be a very significant difference.

    If you're changing from an upright freezer to a chest freezer then you might save a little if you open the door frequently.

    Problem with a chest freezer is the length of time it takes to freeze produce. I know with both our chest freezers it can take over 2 days for the stuff in the middle to freeze properly even when they're 1/2 - 3/4 full. Our upright freezer on the other hand will freeze a 2 or 3 litre bottle of orange juice in around an hour or so.

    If your old freezer compressor is running 24/7 then it may be short of gas as well. Also with old units that ran on freon12, when they have a problem they often get converted to run on R134A. If the conversion isn't done correctly (ie the capilliary tube isn't resized) it could also cause them to run continuously.

    I'd be interested to know how much you save with your new freezer and what your payback time would be. In your particular case there are too many variables but I'd also be interested to know how much it would save in real life if the 10-15 year old unit was running without any problems and it was a like for like replacement with a new one.
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    Quote Originally Posted by AndyD View Post
    Different refrigerants can improve efficiency but in the case of a domestic freezer it wouldn't be a very significant difference.
    One thing that R600a instead of R134a does seem to help with is quieter running. Which I'm guessing is because the former is easier to compress.

    Quote Originally Posted by AndyD View Post
    If you're changing from an upright freezer to a chest freezer then you might save a little if you open the door frequently.
    True. This one doesn't get opened that often.

    What I did notice (and measured) is that the walls on the old upright freezer are 5cm thick and the new chest freezer has 6.5cm thick walls. That works out to a fairly significant 30% thicker. I'm not sure what type of insulation the old freezer has but I'm guessing it's not better than the new one.

    Quote Originally Posted by AndyD View Post
    Problem with a chest freezer is the length of time it takes to freeze produce. I know with both our chest freezers it can take over 2 days for the stuff in the middle to freeze properly even when they're 1/2 - 3/4 full. Our upright freezer on the other hand will freeze a 2 or 3 litre bottle of orange juice in around an hour or so.
    That is interesting although I suspect that this little chest freezer might freeze things in closer to the time taken by your upright freezer. The only way to know for sure would be to do a test with a 2L bottle of orange juice. Not that I freeze fruit juice but I could give it a go and let you know if you're curious.

    Quote Originally Posted by AndyD View Post
    If your old freezer compressor is running 24/7 then it may be short of gas as well. Also with old units that ran on freon12, when they have a problem they often get converted to run on R134A. If the conversion isn't done correctly (ie the capilliary tube isn't resized) it could also cause them to run continuously.
    I'd heard about changing the refrigerant type causing problems when it didn't suit the hardware. I noticed the old freezer had a sticker on the compressor saying R134a but I think that is original gassing but no real way to be sure. I do think that this freezer didn't always run continuously.

    Quote Originally Posted by AndyD View Post
    I'd be interested to know how much you save with your new freezer and what your payback time would be. In your particular case there are too many variables but I'd also be interested to know how much it would save in real life if the 10-15 year old unit was running without any problems and it was a like for like replacement with a new one.
    The new freezer used a bit less than 1kWh (about 0.9) for the first 24 hours. This includes the first 6 hours where it is on but empty and then the transferring of the contents of the old freezer to the new. The next 24 hours used about 0.8kWh. With the recent wind the ambient air temperature has dropped so it's not quite a worst case scenario.

    Currently being charged R1.27 a kWh (block three of the four block tiered billing). Although I read that Eskom wants to change to a 2 tiered block system which leaves a gap for them to up the average price per kWh but we'll have to wait and see what happens there...

    1kw a day costs R463.55 a year to run.

    2kw a day costs R927.10 per year.

    3kw a day costs R1390,65 per year.

    Freezer cost under R2k delivered.

    Now unfortunately I don't know what the old freezer would use if it was in 100% condition and fixing it (thermostat and / or regas) just to measure it doesn't seem worth it having already bought a replacement. However it was using more than 3kWh over 24 hours when measured in it's faulty condition with a pay back of about 2.1 years (at 3kWh versus 1kWh per 24 hours).

    Assuming the following potential usage figures for the old freezer with no faults and no price increase for electricity:
    2kWh a day has a pay back period of 4.2 years
    1.5kWh a day has a pay back period of 8.4 years

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    Thanks for the figures, you obviously have a genuine interest in this. I think with your guesswork figures if a new freezer paid for itself in energy savings in between 4.2 and 8.4 years then it would work out as a R240-R440 saving per annum and would be a hard sell to a potential customer.

    There's lots of ways you could save more than this in an average household without the R2000 capital expenditure. When you consider that if you replaced a single 500w halogen floodlight running for 8 hours each night with a 30w LED equivalent you'd be laying out R500.00 and saving R2000 per annum. Payback time would be 3 months and actual rand savings would be five times what the freezer is giving you.

    I would suggest in normal circumstances replacing appliances would only be viable as a part of a much larger energy saving plan and would probable fall under the final phase of that plan once more effective and less costly measures have already been taken such as lighting replacement etc.
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  11. Thank given for this post:

    Dave A (26-Mar-13), ians (25-Mar-13), Justloadit (25-Mar-13)

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