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Technical Help needed on GSHP and KW/HR use

Post in 'The Green Room' started by mbcijim, Jan 24, 2009.

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  1. Jerry_NJ

    Jerry_NJ Minister of Fire

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    woodgeek, thanks, and I think I overlooked the transportation/delivery charge. Is that yet to be added to the 10 cents for wind power? I pay about 11.5 cents for electricity and 6 cents for delivery. When the lines start coming down in an ice storm I understand why the delivery charge is so high.

    Jersey Central Power and Light (returned to this name, but it is really "First Energy" and I forget what it was before going back to JCP&L;) is about 50/50 coal and nuclear, so they too have a lot of nuclear capacity that does what when it isn't generating power? Maybe they just "pull the rods" back and slow down the reaction.

    I have no idea what heating oil cost, but I thought it was down near $2 a gallon when regular gas was selling for about $1.50 (gee I forget already how low it recently got, it is in the $1.70+ range now for gas). I last had oil heat in 1974. I had natural gas heat in Ohio and then back in NJ 1974-1989. Since I have been on a heat pump, and a geothermal since 1993...one of my better decisions.

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  2. woodgeek

    woodgeek Minister of Fire

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    Jerry--the rate I gave is the sum of all sub-charges, including delivery. They break it down into about 10 parts (all per kWh), but it comes down to 15 cents summer and winter (base), 7.5 winter heat, and 2.5 wind surcharge.

    So at 60MMBTU/yr since 1993, does that put you in the 'billion BTU served' club soon?
  3. mbcijim

    mbcijim Member

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    Thanks for all the help guys.

    My power is from PPL, and $.10/KW is all in (transmission, generation, etc...). HOWEVER, they are predicting $.13-$.14/KW January 2010 when deregulation kicks in.

    I have about 10 cords on the ground from where my new house was built. I spent a few hours more on it today and I am up to 5 cords split & stacked. I do it just for excercise. It gets me off my butt and the computer. I have 8 cords coming in May, I traded a guy for some free wood.
  4. Jerry_NJ

    Jerry_NJ Minister of Fire

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    Woodgeek,

    Well as 1000/60 = 16.6 guess just heating has put me near the Billion club. Given I also have lighting, cooking, washing, some hot water, and cooling to add to the heating, I'm well ove 1 billion BTU since I went geothermal. Gee, to hear our (USA) federal government talks (in dollars not btu) a Billion is "chicken feet", lets talk trillions. Oh, oh, on a slippery slope here for "off-topic" deviations.

    mbcijim, wow 10 cords, I can't even imagine, the most I've ever had on one time is about two cords, and that seemed a lot. But as the geothermal exchanges have made abundantly clear, I'm not a 24/7 wood heating guy. Reminding my self of that, I'd say my total electric driven BTUs is below the engineered load of 60M BTU. I haven't done the calculation/measurement, but a rough guess is I use 35M BTU of electric heating from the GHP each year...about 3,500 KWH per heating season.

    I'm on this forum mostly because of my interest in wood heating, but I remain a "gentleman" wood heating guy. Some for profit, mostly for enjoyment, and emergency back-up.
  5. semipro

    semipro Minister of Fire

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    We also have a GSHP that runs when the wood stove doesn't.

    This has been a very informative discussion on GSHP that I think others will reading for a while to come including those trying to decide whether or not they want to invest the money to go with GSHP.

    Two considerations WRT to GSHP that I don't often see mentioned though:
    - Noise: with GSHP the compressor is typically located inside the house as opposed to outside. This is nice in that you don't have to listen to the compressor running when you're outside in the summer but it can result in more noise in the house depending on installation.
    - Temps at the register are usually higher - Since GSHPs use a heat sink/source (soil, water) that is typically around 55 degrees F year round, the temps at the registers when heating are typically higher than those of a typical air-source heat pump that uses outdoor ambient air as a source/sink.
  6. karl

    karl Minister of Fire

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    270 Kw ??? That's 47 amps of 220 running 24 seven. NO WAY!!! check my math here.

    270,000 watts times 3.413 btus per watt equals 921,510 btus That's if you used resistance heat. If you have a COP of 2 then you're at 1,843,020 btus. That's what you would get with a decent heat pump. The cop's on your pumps are roughly 4.5. Therefore you're making 4.14 million btus of heat a day. THAT'S FREAKIN' INSANE. There has to be something wrong. I have a 2600 square foot house in West virginia and my gas furnace can only produce about a little over half that much heat in a day. To match that output I would have to run the furnace none stop, and burn the Summit the pretty hard with regular loadings. Something isn't right with that system. I doubt your back up packs would even pull that much. Are you sure you're reading your meter correctly.

    Buy a second Summit and that thing won't run at all next year. Actually, the one Summit is going to take chunk out of the heating needs.
  7. Jerry_NJ

    Jerry_NJ Minister of Fire

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    Karl,

    You've lost me. Where did you get the 270 KWH (I assume hours) .. and was that per day? That is too high for any residential application I can imagine. Who gave that number, was it me and I forgot/can't-find?
  8. karl

    karl Minister of Fire

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    In the first post of this thread. 120-270 KW/day. It was 270 a day not an hour, but still whole lot.

    He says in a later post he's got it down to a hundred or so and is attributing 80 to the heat pumps. With his COP that's 1.22 million btus a day or around 51,000 btus an hour. I think that number is a little low though. A Summit stove will put that much out with ease and I don't think he's going to heat 3500 square feet with that stove.
  9. Jerry_NJ

    Jerry_NJ Minister of Fire

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    Yes, I didn't look back but do recognize/recall the post. There are in the first case dimension errors, that is 120-270 KW must be 120-270 KWH, that is energy, not power.

    I'm not trying to defend the numbers from "mbcijim", but at 270 KWH/day one uses an average of 11.25 KW of power, constant. My GHP has 10 KW of Auxiliary resistive and runs at about 3.3 KW when in the high/second stage HP heating (about 35,000 BTU). That alone would be 13.3 KW for my peak power into my heating system, or higher than the average amount you question, of course the resistive auxiliary hear is almost never on in my system. Running full blast my GHP plus Resistive Auxiliary heat would be putting out about 70,000 BTUs and that would in short order run us out of the house if the temperature outside was about -20 degrees. As posted somewhere in the past we have a well build (all electric) 2,000 square foot two story.

    Some of my other numbers, estimated on electric usage data, says in a really cold 24 hour period, we had one recently with sub-zero nights and low 20s for day highs, suggest my system uses when not supplemented with wood heat, a 50-55 KWH per day, a lot less that the subject, but that did get down to a hundred or so, and at 3,500 square feet that sounds about right to me for a well insulated house under similar weather conditions. He noted problems with too much use of resistive auxiliary heat when he hit those bankrupting usage rates of 270 KWH/day.
  10. mbcijim

    mbcijim Member

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    I did post 270 KW and I did mean 270 KWH in 1 day. I was going off memory when I posted it.

    I looked in my log, and I had written 235 KWH in 1 day, so my memory was off by 35 KWH. Then I checked my math, and I screwed up. I check my usage usually every day (and log it), well it was 3 days between recordings, so I found a second error - I thought it was two days. My worst usage in my house was 470 KWH in 71 Hours, which is really 159 KWH/1 day. So I was wayyyy off. My apologies. I'm usually much better at math. I'll have to take some time and enter all the numbers in a spreadsheet.

    I don't expect my Summit to heat the hole house. It's in the basement. The second floor is not above the area with the stove, it's at the opposite end of the house. The living room and master suite are above the stove, so it will heat the main living area (I hope). The Summit is a hobby. I wanted a wood fireplace, wife wanted propane. She won. The basement is the man cave, so I put in a woodstove.

    It's our dream house. I didn't neccesarily do things the cheap way, or the most effective. We did what we wanted. I'm sure that Al Gore would hate me. The woodstove is a hobby.

    We had temps in the high 40's today and I used 101 KWH in 26 hours.
  11. Jerry_NJ

    Jerry_NJ Minister of Fire

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    Good, scrub the numbers and get the rounding errors and typos out. I think overall this has been an good and informative thread. It has caused me to track my usage and as the weather has warmed a bit I am totally on HP, no wood heating for about three days. I'm burning about 40KWH per day, and that's with the temperature never above 66, and set at 60 for at least 10 hours overnight. The usage of 40 KWH is for everything, I don't have anyway to extract the exact amount for HP, but I do know by back-ground usage is about 800 KWH a month, or 25KWH+ per day, not bad, that says I'm using only 15KWH for the HP which at our usage now is at least 90% of our hot water too. I had to turn the electric hot water tank back on last night when the dish washer was going following some post/pans and counter cleaning after dinner. The warm day (about 50) lowered the RT on the HP. I estimate I used 1 or 2 KWH of resistive for hot water, which is in my total number. I do think the hot water tap on my HP is a good addition, now that I've re-plumbed it so that the water flow to/back from the HP is unrestricted my mineral buildup.

    Don't worry about Gore. Anyone who flies around in a private jet, and lives in a house (don't know the exact size or even how many) with more square feet in the garage than I have in my whole house shouldn't, but DOES, criticize others for their impact on GLOBAL WARMING. Have you noticed how cold it has been this winter?
  12. mbcijim

    mbcijim Member

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    I entered the numbers in a spreadsheet to get rid of human error.

    I averaged 5.84 KWH/Hour when I was using my resistive heat as a supplement and had 6 degree setbacks during the 8-5 period and sleep time.
    I averaged 4.56 KWH/Hour when I was using my resistive heat as a supplement but had no setbacks.
    I averaged 4.26 KWH/Hour when I wired the resistive heat to manual turn on only and no setbacks. This data period is only 7 days old though and it has been unseasonably warm a few of those days. Last few days are under 4.00 KWH/Hour.

    Conclusion: The setbacks were hurting me a lot more than the resistive heat as a supplement. Need more data to track to a decisive conclusion.

    I think my middle number of 4.56 KWH/Hour is fair. That translates to 3,300 KWH/month. Assuming 900 KWH of background use, I am using 2,400 KWH/month to heat the home. In Pennsylvania that number will hold from 12/15 - 3/15 and significantly less in the shoulder seasons.
  13. mbcijim

    mbcijim Member

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    Another update:

    House has been re-wired so that auxillary electric resistance heat only turns on manually. We've had average February temperatures for the last 11 days and I averaged 100.6KWH/Day. I used a spreadsheet so no more math mistakes. I'm pretty happy with that.

    Basically it is costing me $200/month to heat the home in the coldest parts of winter. (I'm right around $.10/KW and assuming 35 KWH/Day background load).

    Today we are turning on the basement, which will condition another 2,200 sft. However the basement stays 60 with no temperature control. I'm not sure if I believe it, but my HVAC guy is telling me it will be cheaper because the basement ceiling (flooring on the 1st floor) will be heated to 68-70 now. That flooring is 100% wood/stone, so it does have a lot of mass. Time (and my spreadsheet) will tell!

    That and I can finally get the Pacific Summit running! They are turning on the basement return, and it has a huge intake right over the stove. I might run the stove all weekend and see what happens.
  14. Jerry_NJ

    Jerry_NJ Minister of Fire

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    mbcijim,

    Looking for more data. I'm running a three times a data data collection on my overall electric usage. I also note when I am using wood heat, and when I do it is usually from about 6 pm to 2 am. I don't try to burn overnight, and assume the insert has slowed down to a point at 2 am that the HP has to turn on to hold the main floor at 60 degrees. When the insert is running the HP is off, only the circulation fan is running on low. Still, this says the HP is off for at least 8 hours, or 1/3rd of the time, and during the time of lowest outside temperatures. Still I don't see large differences in the 4pm to 9am power consumption with or without the wood heating. I'll do more data parsing to see if I have enough to compare costs. I have to pay for much of my firewood, it isn't "free". It is clear the 8 hour wood heat cycle isn't saving more than 15 KWH per day. I still enjoy the wood fire, and with it going the living room is warmer than when I'm running the HP, 70+ degrees verses 65+ degrees with the HP.

    Where in Schuylkil County do you see the mountains in your avatar ; > ?
  15. mbcijim

    mbcijim Member

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    I haven't collected that data yet. Possibly this weekend I will run the wood stove and monitor the geothermal, but they are also calling for 40*+ days this weekend.

    The only thing I can tell you from experience is that when we start up the wood stove in the 30*-40* cabin, it takes a good 3-4 hours to throw off heat. For the first few hours it's just warming up the chimney, stove, etc... But I suspect that your woodstove is making more of an immediate difference with existing 70* temperatures. Plus I think you have enough experience to know that already.

    I just like the picture in my avatar! I just was out in Montana and shot a nice 328" Elk in November. My picture reminds me of the trip.
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