Saving energy with the .NET Micro Framework

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The Discussion

  • User profile image
    barrkel

    The premise of the article - that the proportion of hours where hot water is needed is the same as the proportion of energy that is actually required - is false. Unless you have a terrible insulating system, a huge amount of energy isn't required to keep water hot. Most of your energy use should be in heating up cold water which is taken in to replace hot water used. You will not see a 66% reduction in energy costs; how much you will see depends on how good or bad your hot water insulation is, and the temperature differential between the hot water and the ambient temperature in its surroundings. Whatever that saving is, it needs to be compared with the opportunity costs of not having hot water whenever you want it, but rather having to stick to a schedule.

    That's not to take away from the cool DIY scheduled servo job, which looks neat.

  • User profile image
    Jeff Birt

    I like to see unique projects like this. We have an electric water heater that has this type of feature built in, have not see it on a gas unit though. The cut back does help a little but like barrkel said you have to consider the amount of energy needed to heat up a large volume of water between your two set points. The other area of concern is that the automation of the gas valve may lead to a dangerous situation. Since the position of the valve is not monitored a slip of the band clamp or glitch of the program has the potential to heat the water more than expected leading to possible scalding. Just be careful.

  • User profile image
    ijimeko

    @barrkel: you rock!

  • User profile image
    Clint

    @barrkel: Fabien is from Seattle, the days it drops below 45 I can count on one hand each year.  Different regions have different heating needs.  If you're in Alaska, you'd want to focus your energy savings somewhere else.

  • User profile image
    FabienRoyer

    @barrkel: Hi Barry. Thanks for sharing your thoughts.

    Unfortunately for us, the gas water heater was installed in the garage by the builder when the house was built. In the winter months, it really gets cold there and the temperature differential between the hot water and the ambient temperature of the garage leads to waste. After installing this hack, I also wrapped the gas water heater in insulation to help reduce the loss. The perceived constraint of having to stick to a strict schedule is actually not that bad since the water still remains warm for quite some time after the heat is lowered.

    @Jeff Birt: the servo can only physically go from 0 to 180 degrees: the way the mechanical coupling works with the valve, calibrated to be on the HOT setting at the full extent of the servo's arm, it is impossible to get into a dangerous situation where the water would become too hot. The water never gets stone cold as the temperature is only lowered to a low heat setting, so it never takes a huge amount of energy to heat it back up.

     

    I plan on having a follow-up article on the actual savings in a few months: the proof will be in the pudding Wink

    Cheers,

    -Fabien.

  • User profile image
    Silvio

    Just curious as to what the "low" temperature is set to?  Not sure if you are aware, but if your water tank temperature drops below 120*F (50*C) Legionellosis will start to grow in your water tank (see Legionnaires disease.)  This is very serious.  There was a recent incident at the Playboy mansion where people had a run in with Legionnaires disease.
    http://en.wikipedia.org/wiki/Legionellosis

  • User profile image
    FabienRoyer

    @Silvio: Hi Silvio. I am aware of this bacteria. When the water temperature is hot, it stays hot for long enough to kill any potential Legionellosis bacteria. Also, Legionellosis is more of a concern in cooling systems. This issue has been discussed a few times on the original post: http://fabienroyer.wordpress.com/2011/02/22/saving-energy-with-a-netduino/

    Cheers,

    -Fabien.

  • User profile image
    magicalclick

    Is it really necessary? The insulation would make lose of heat very marginal. Sure higher temperature difference will lose more heat, but, it shouldn't be too much. I like your direction, but, it would be better doing it at air condition kind of situation.

    I didn't know the full extent, but, please make sure you have a safty measure when that thing going beaserk. Just imagine Final Destination happens and you have some kind of fuse to stop it happening.

  • User profile image
    QuickC

    This is a good artical with great idea, great artical however,,,, I see a new hot water heater in your near future.  Both the servo and the Knob it's turning are likely only rated for 5000 to 10000 action before they fail.  In other words, the parts are not designed to be used daily.  Durabilty needs to be considered when the costs like a new water heater are large.

  • User profile image
    8r13n

    @QuickC: Going with your figures and his schedule it seems like he should get at least 6 years of use.

    (5000 lifespan uses / 2 daily uses) / 365 days = 6.8493150684931506849315068493151 years

    Or, since it's PI day....

    2.1802046998889772023134762105824 * PI

  • User profile image
    Jon Udell

    I /love/ the popsicle sticks!

  • User profile image
    Vuosaaren ATK

    Hi Barry. Thanks for your work!

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