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The cold hard numbers of my Heat Pump + part II

Post in 'The Green Room' started by Amaralluis, Jan 27, 2011.

  1. henkmeuzelaar

    henkmeuzelaar New Member

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    Thanks for the real-world energy budget data Mr. Heat Miser. I have noticed that most pellet stove manufacturers talk about 100 Watts, or so, electric power consumption.

    This might, of course, reflect advances in blower and/or auger technology since you bought your stoves or it might mean that blower and/or auger might have started to use a bit more power as they aged and friction losses in bearings increased...

    Either way, it is very useful to have these type of data when planning a new home heating system.

    Henk

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  2. Amaralluis

    Amaralluis Member

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    Thanks for the numbers. They do confirm my suspicions.
  3. Mr. Heat Miser

    Mr. Heat Miser New Member

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    Actually, the 20 year old Whitfield uses less power than my brand new 2010 Harman P35i, which was surprising to me.
  4. Mr. Heat Miser

    Mr. Heat Miser New Member

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    This 1 kWh for every 20 fires is only counting the total juice the stove consumes while the igniter is on. For a more accurate overall consumption for the Whitfield (which does not have the auto igniter) the numbers are about 2 kWh per day, or 60 kWh per month.
  5. Amaralluis

    Amaralluis Member

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    Got my february hydro bill.

    Heres the numbers.

    2010 697Kwh for a period of 31 days.
    2011 1587kwh for a period of 28 days.

    This results for 2010 in a daily consumption of 22.48Kwh and in 2011 56.68Kwh which makes a difference of 34.19kwh more in 2011 compared to 2010.
    From this amount I take out 13.10kwh for the extra person in the household (read my first post) and Im left with 21.10Kwh daily usage for the heat pump.

    21.10*28days for a total of 590Kwh for the period of 28 days.
    At 11cents/kwh, the cost of the heat pump was approx $65.00.

    I had to shut down the heat pump for one evening. The temps dropped below -20C and the heat was still blowing warm air but the defrost mode kicked too often and it couldnt keep the temp in the house. Used one pellet bag for the night. ($6.20)

    The hard numbers? Assuming It would only burn one bag a day, the pellet stove would cost 28*$6.20=$173.
    $173-$65-$6.20=$102 savings. Not bad.
  6. semipro

    semipro Minister of Fire

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    Interesting idea and one similar to something I've considered. My thought: take a flowing source of water such as a spring, pipe that to a tank so that there's a constant flow of water, and then immerse your Heat pump unit's external coil in this tank (just the coil of course not the compressor or fan).

    Of course a freon to water heat exchanger would work better but I was just thinking...
  7. henkmeuzelaar

    henkmeuzelaar New Member

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    That's a bold mod, especially since it would not be easy to ever revert back to the original freon-to-air configuration without buying a new HP.

    However, I do like the fact that it does not mess with the intricacies of trying to re-balance a delicate air intake fan. Perhaps this is something I might be willing to try in a situation where the air intake fan was already toast (e.g. after being buried under snow and ice for a long time).

    Did you already think through how this setup might (or might not) work if you needed to cool the house in summer??

    Henk
  8. woodgeek

    woodgeek Minister of Fire

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    Um, why not buy a small geo system and feed it water from the spring rather than hack an ASHP? The unit costs are not the problem--its the drilling.
  9. henkmeuzelaar

    henkmeuzelaar New Member

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    Well, so far the discussion has been about what to do if you already do have an ASHP and don't want to buy additional geo HP.

    However, your suggestion might even be worth pursuing for a new installation.

    All three ideas (i.e. yours, Semipro's and mine) , however, are only worth pursuing if the ground water flow used can be disposed off in an economical manner. In my county, that means reinjection at 18+ ft depth (potentially deeper, dpending upon a hydrogeological survey). So, at least some drilling costs will always be incurred.

    Henk
  10. Amaralluis

    Amaralluis Member

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    I got my december hydro bill and heres the cold hard numbers about my heat pump vs pellet stove since it was installed on November 1st.

    My electric bill runs from around the 17th of every month. For Nov/Dec period in 2009 I’ve used 572KWH for a period of 28 days (I know it was awesome) with the pellet stove. In 2010 the total was 1298Kw for a period of 29 days with the heat pump.
    For dec/jan then the usage was 786KWH for 2009 and 1739KWH for 2010.

    The difference between 2009 and 2010 besides the pellet stove we had a teen that moved in August, which increased the electric usage for quite a bit. It was not a constant difference so what I did is that I took the difference between 2009 and 2010 for august, september and October and calculated the average of the difference for those months. With it Im assuming that approx 390Kwh over 30days are because of the extra person in the Household. I know that its not super accurate but Its the only way I thought to get an idea of how much the person costs. If someone has a better idea please let me know.

    This means that for nov/dec period the heat pump used approx 336Kwh and for dec/jan 563Kwh.
    The hydro price is $0.11, 336*0.11=$36.96 and 563*0.11=$61.93.
    Pellets used for the same period of time in 2010 = 0

    Unfortunately I didnt record the bags usage in 2009 so I dont know exactly how many bags were used, but I can safely say that it would averaged one bag per day so 29+33=62 bags. Cost of Bags $6.20 (with the taxes).
    62*$6.20=$372.22

    There you have it, $372.22-$98.89=$273.33 difference.
    Are this numbers accurate?
    No.
    Do they tell me something?
    Yes, the heat pump is saving me money from pellets, It might not be saving me $273 up until now, but it is undoubtedly saving me money.

    PS - I know that the pellet stove also used electricity but I cant put a KWH value to it but from the readings in 2009 it was not considerable.
  11. Amaralluis

    Amaralluis Member

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    Got my february hydro bill.

    Heres the numbers.

    2010 697Kwh for a period of 31 days.
    2011 1587kwh for a period of 28 days.

    This results for 2010 in a daily consumption of 22.48Kwh and in 2011 56.68Kwh which makes a difference of 34.19kwh more in 2011 compared to 2010.
    From this amount I take out 13.10kwh for the extra person in the household (read my first post) and Im left with 21.10Kwh daily usage for the heat pump.

    21.10*28days for a total of 590Kwh for the period of 28 days.
    At 11cents/kwh, the cost of the heat pump was approx $65.00.

    I had to shut down the heat pump for one evening. The temps dropped below -20C and the heat was still blowing warm air but the defrost mode kicked too often and it couldnt keep the temp in the house. Used one pellet bag for the night. ($6.20)

    The hard numbers? Assuming It would only burn one bag a day, the pellet stove would cost 28*$6.20=$173.
    $173-$65-$6.20=$102 savings. Not bad.
  12. semipro

    semipro Minister of Fire

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    My question is basically academic. We have a geothermal heat pump. I was just wondering if someone already had an air-to-freon heat pump and a ready source of flowing water.
  13. semipro

    semipro Minister of Fire

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  14. begreen

    begreen Mooderator Staff Member

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    I have friends that are looking at installing this unit. How large a home is this unit heating? It sounds exceptionally well insulated. Based on Daikin's specs, it would be putting out less than 8000 btu at around -9ºC (15F). It's amazing to hear that it would be putting out enough heat at temps far below zero (-18ºC -4ºF) considering the sharp drop off in heat output at lower temps. Was there supplemental heat in the building at this temperature?
  15. Amaralluis

    Amaralluis Member

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    why was my part ii thread merged with this one??
    This one has gone offtopic and I wanted to start it over to discuss other people experiences.
  16. begreen

    begreen Mooderator Staff Member

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    Yes, trying to bring it back on topic by understanding the numbers. Had friends over yesterday and I showed them the thread as they are looking into your unit. They currently have a pellet stove, but pellets are half your price. The questions that arose were the size of the house and temps in 2010 vs 2011.

    Did you get the degree day comparison between the 2 years?
  17. Amaralluis

    Amaralluis Member

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    My house is a approx 1300sqft bungalow style with an unfinished basement.
    Heres the degree days comparaison between 2009/2010 and 2010/2011.

    2009.....oct/nov.......427.1.............2010.....oct/nov.....383.1
    ............nov/dec......534.4.........................nov/dec.....541.4
    ............dec/jan.......708.8.........................dec/jan......670
    2010.....jan/fev.......764.9..............2011.....jan/fev......879
    ............fev/mar......523.1..........................fev/mar

    The date range is from the 17th to the 16th of the following month to match my electricity bill cycle.
    I used the Heating degree days from the chart found here : http://www.climate.weatheroffice.gc...ationID=6207&Day=1&Month=2&Year=2009&cmdB1=Go
  18. begreen

    begreen Mooderator Staff Member

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    Excellent, thanks. This is what I wanted to see. It looks like jan/feb this year was a lot colder, so the savings are actually better for the heat pump than initially calculated. The unit appears to be performing very well. This is impressive performance. Is the Daikin unit carrying the full load all this winter?

    Our friends move in tomorrow. They will have about the same electric rates, but they get better pellet pricing. Their house is about 1500 sq ft, in milder temps, so this looks pretty good for them.
  19. Amaralluis

    Amaralluis Member

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    The heat pump has been the sole heating source this winter except on one occasion when the temps dropped below -20 during the night.
  20. begreen

    begreen Mooderator Staff Member

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    Very impressive! That is quite awesome.
  21. Amaralluis

    Amaralluis Member

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    Finally got my bill for the Fev/Mar period. The results are very surprising, it makes me wonder if the reading last month was a real reading or just an estimate from the electric company.

    Heres my results:

    Fev 17 to Mar 16 in 2010 - 632Kwh 29 days - 523 Degree days
    Fev 17 to Mar 16 in 2011 - 1223Kwh 29 days - 640 Degree days

    Difference between 2010 and 2009 - 591kwh or 21.79kwh daily.
    Take the average usage from the new person in the household 13kwh/daily, the heat pump used approx 20.80Kwh/day or 211.21Kwy for 29days.
    At 11cents/kwh the total for the heat pump was $23.5.

    Theres a few points that skew these numbers. on the last week of february because of a sensor problem that had to be replaced the heat pump was off and I used the pellet stove instead. In total I used 7 bags, one per day.
    At $6.20/bag it cost me in pellets $43.40. Obviously had I not have the problem with the heat pump, its cost would be higher. That week was probably the coldest period too.

    Regardless, the hard numbers? Assuming It would only burn one bag a day, the pellet stove would cost 29*$6.20=$179.80
    $179-$23.5-$43.40=$112.90 savings. Still not bad.

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