Electric Stovetop Cooking: Conservation ideas

Discussion in 'Environmental Discussion' started by SageBrush, Apr 2, 2013.

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  1. SageBrush

    SageBrush Senior Member

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    Re: HPWH heat pumps, the 'lower limit' of temperature utility is a bit of red-herring because AFAIK no threshold for how much better is specified. OTOH, I bet you can pretty easily calculate a reasonable estimate of average annual COP by starting with historical average minimum and maximum daily temps by month and then using published heat pump efficiency data by ambient temp.

    Out of curiosity I recently calculated heating days for my Albuquerque climate using this temperature data and found they were within ~ 5% of published numbers. Heck, for all I know that is how degree days is calculated ;)

    IIRC, I estimated that a heat pump in my garage would have an average annual COP of ~ 1.8.
     
    #81 SageBrush, Apr 21, 2013
  2. fuzzy1

    fuzzy1 Senior Member

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    Here are some COPs (Energy Factors) as restated under the recent Northern Climate Specification. Note that these are uniformly lower than the numbers advertised by the manufacturers, which are based on a prior specification more typical of the whole country. I don't recall the actual NCS formulation, but seem to remember something about averaging the COPs for the original spec (based around 67F ambient) and for a colder condition (based around 45F). But my garage is colder than that for several months each year.

    Northern Climate Qualified Heat Pump Water Heaters

    This list really has only a few basic models, but sold under numerous brand names. Note that one common model is very conspicuously absent, because it fails to meet even the NCS Tier 1 requirement. Some of the tests show that its heat pump action becomes ineffective below about 65F, and some operational issues cause it to be less efficient than regular electric heaters at lower temperatures.
     
    #82 fuzzy1, Apr 21, 2013
  3. SageBrush

    SageBrush Senior Member

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    Fuzzy,
    Have you considered a waste-water heat recovery unit ?
    I see that PSE (Puget Sound) offers a $250 rebate. If you can do your own plumbing this comes close to being free after rebate.

    In conjunction with a ASHP (perhaps installed later when tech is mature), energy for hot water use would be about 55% less than resistive heating in your climate. This EPA study pdf suggests about a 20% energy savings from the pipe alone.

    Addendum: This report says 35% reduction in energy use from the pipe.
     
    #83 SageBrush, Apr 21, 2013
  4. SageBrush

    SageBrush Senior Member

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    Last Update (for a while, if my wife has a say in the matter):

    All breakers off: 7 - 9 watts. I'm waiting to hear from my utility if they can fix the draw.
    Gremlin I'm too lazy to kill: Bedroom fan with a remote control -- ~ 3 watts

    Gremlins allowed to survive:
    3 watt garage light
    6 watt (router + modem)
    1.5 watts iMac sleeping
    3 watts Electric range display

    Gremlins slashed:
    Doorbell transformer (16 V, 10 VA) removed
    Garage door openers -- disconnected
    Microwave (4 watts) put on switch
    Furnace disconnected until needed
    Smoke alarms (2) disconnected. I'll replace with low consumption devices. I'm looking for something that is cat friendly (not high pitched and so loud that they run and hide.)

    Major changes since my 150 kwh/month consumption:
    Heat lights in the BR removed -- plan to replace w/ 25 watt total LED
    All-clad skillets now used for cooking instead of cheap Teflon pans with poor element cover
    Pending: Immersion water heater and Nissan Thermos for 1.5 Liters a day


    So now my home if nobody home but fridge operating and surviving gremlins running consumes about 50 watts = 1.2 kwh/day. Last 24 hours with us at home, less than 3 kWh consumed. My electric bill cycles ~ the 25th, so I will see if monthly consumption is in fact less than 100 kWh for this time of year in a little over a month.
     
    #84 SageBrush, Apr 21, 2013
    fuzzy1 and xs650 like this.
  5. fuzzy1

    fuzzy1 Senior Member

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    I've seen them displayed repeatedly, but haven't yet put much thought into them. Some immediate issues:
    (1) "Equipment must be installed vertically. Horizontal application is not eligible". My crawlspace is lacking in vertical space. A (non-qualifying, lower performance) 30" model should fit. I'll have to check closer to see if 36" might work;
    (2) I'm not a PSE customer, so no rebate;
    (3) I don't do that much plumbing. Yet. But after getting confident enough to add a new breaker and wiring to a live electric service panel for the water heater move, maybe that level of plumbing should be my next step.

    It seems that these products want a vertical installation so the waste water flows in a film on the entire inside surface, maximizing heat transfer area. I have little vertical space available, but plenty of horizontal. Has anyone seen any studies on horizontal applications?
     
    #85 fuzzy1, Apr 22, 2013
  6. SageBrush

    SageBrush Senior Member

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    Yep -- I have only seen vertical installations. However, I'm confused by your desire to put it into a crawlspace. I think it is usually installed near the water heater, although sometimes it is installed near a shower.
     
    #86 SageBrush, Apr 22, 2013
  7. fuzzy1

    fuzzy1 Senior Member

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    What is this light for? Is it just something to provide minimal lighting for errands while popping into the garage? If so, consider something like this 1.1W lamp that I use for a back bedroom (on a timer, thought the timer probably uses almost as much as the light itself):
    Feit Electric A15 LED Shape, Standard Base, Clear
    or the similar 0.9W item:
    Feit Electric LED Globe, Clear
    I'm quite impressed about how much light is available from just 1 watt.
    That level is still a long way off for me. But the idea of upgrading this house to net-zero is now seeming to be at least possible, though only for principle and a statement, not as something that is yet cost effective. Before that, I'd need to knock off at least another 2000 kWh/year, then see if half the remaining load can be displaced by PV with the existing tree impairments.
     
    #87 fuzzy1, Apr 22, 2013
  8. fuzzy1

    fuzzy1 Senior Member

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    Aren't these installed in wastewater lines? With a one story home and no basement, the elevation drop from the shower drains to the outgoing sewer pipe is only a few feet. Getting more vertical for a tall heat recovery unit would require a pump to push that warm wastewater up to the top of the device.

    I believe Seattle is already looking at selling rights to heat recovery from major urban wastewater lines. These won't be passive heat exchangers, but instead active water-source heat pumps.
     
    #88 fuzzy1, Apr 22, 2013
  9. SageBrush

    SageBrush Senior Member

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    An older, very spoiled, very finnicky cat who needs encouragement to use the litter box.
     
    #89 SageBrush, Apr 22, 2013
  10. SageBrush

    SageBrush Senior Member

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    Makes sense. Yes, they are put inline with wastewater. I suspect you are right that your home is not a good fit.
     
    #90 SageBrush, Apr 22, 2013
  11. fuzzy1

    fuzzy1 Senior Member

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    3W is much better than the 100W my old neighbor provided in her basement for her cats. (Mine enjoyed visiting for a quiet nap place too.)

    But I'd be shocked if your cat is blind enough that this 1W Feit is insufficient. I can easily read by it, though the aging eyes will fatigue faster than with good light.
     
    #91 fuzzy1, Apr 22, 2013
  12. SageBrush

    SageBrush Senior Member

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    The cost of a failed experiment is just too high.

    I have given some thought to increasing the amount of passive light into the garage so that I can turn the bulb off for 1/2 the day, but my wife is demanding that I now attend to her list.
     
    #92 SageBrush, Apr 22, 2013
  13. SageBrush

    SageBrush Senior Member

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    Fuzzy1, this fellow seems to have made a horizontal heat exchanger.
     
    #93 SageBrush, Apr 22, 2013
  14. fuzzy1

    fuzzy1 Senior Member

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    Here is another one I found last night: Ecodrain -- Nauhaus article. This is not going onto an immediate project list, but just into the bin of future concepts that I need to be aware of and collect more information.

    While two days with a meter on the hot water heater isn't enough to project very well to the whole year, it is showing that my old guesstimate / swag of 2000 kWh was too low. The real number will likely be in the neighborhood of 3000 kWh. (The energy label shows 4662 kWh, but I presume that is for a larger family with more typical appliances and usage.) (Because the heater was just moved, increasing pipe length and standby losses, and the new piping won't be fully insulated until the planned HPWH is settled, this number might not be representative of our past use.)

    While this number is bad news in one sense, it is good news in that the planned heat pump water heater should knock off a larger chunk of home energy consumption. That could make < 6000kWh/year easy, so that I could aim for <5000 in the next project cycle.
     
    #94 fuzzy1, Apr 23, 2013
  15. SageBrush

    SageBrush Senior Member

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    My first full month electric bill since I started this thread:

    PNM -- 3 months.png

    Happy to say I broke the emotional < 100 kwh a month barrier. Somewhat like a 70 mpg tank with the Prius ;)
    I imagine this level of consumption will not be difficult to maintain for the next 6 months, but winter will be a challenge.
     
    #95 SageBrush, May 28, 2013
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  16. SageBrush

    SageBrush Senior Member

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    Update: Tomorrow will be two full months since I made the changes intended to go under 100 kWh a month home electricity. As of today at 9am the meter shows 195 kWh for 60 days. Any hopes of say 2.5 kWh a day are just not going to happen while my refrigerator toils in the summer heat and we use fans to cool down the house at night and for personal comfort.

    Ah well, on the bright side I reduced my 'always on' load by ~ 2 watts by replacing an overheating DSL modem (ActionTec M100) with an ActionTec GT701D that draws about 2 - 2.5 watts. It cost $25 used through Ebay. These cheapo electronic devices all seem to have crappy cooling so finding ones with lower power draws has functional and reliability aspects as well as energy savings.

    Addendum: Somewhat by chance I came across this wireless router with open firmware:
    TP-Link TL-WR703N - OpenWrt Wiki
    0.5 watts !
    I'll have to remember it when my LinkSys dies. A mini-web of low power routers appeals to me more than a central beast.
     
    #96 SageBrush, Jun 23, 2013
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