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Old 06-25-2009, 12:01 PM   #16
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(another) Fair quote?


A 100 amp sub panel is undersized for a 20 KW strip heat package and any other load.

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Old 06-25-2009, 12:09 PM   #17
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(another) Fair quote?


Quote:
Originally Posted by AndrewF View Post
getting a $500+ electric bill in January was not expected.
1362 HDD for January for Dayton, OH. At 8 cents/kwh average rate in Ohio this is 8.7 kw all the time, 7 therms in 24 hrs.

For a 2000 sq. ft. house including basement it's 350 BTU/day/sq.ft.
1362 HDD/31 days = 43.9 HDD in one day
350/43.9 = 7.8 BTU/sq.ft./HDD, slightly above the average 6 BTU/sq.ft./HDD.

Last edited by Yoyizit; 06-25-2009 at 12:22 PM.
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Old 06-25-2009, 01:16 PM   #18
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(another) Fair quote?


Quote:
Originally Posted by beenthere View Post
A 100 amp sub panel is undersized for a 20 KW strip heat package and any other load.
It was borderline based on the numbers I ran, but since I couldnt find 125 amp breakers for my #2 copper cable, I used 100 amp.

I also have it wired so that the full 20kw doesnt come on unless it is really needed based on a smart thermostat.

Quote:
Originally Posted by Yoyizit View Post
1362 HDD for January for Dayton, OH. At 8 cents/kwh average rate in Ohio this is 8.7 kw all the time, 7 therms in 24 hrs.

For a 2000 sq. ft. house including basement it's 350 BTU/day/sq.ft.
1362 HDD/31 days = 43.9 HDD in one day
350/43.9 = 7.8 BTU/sq.ft./HDD, slightly above the average 6 BTU/sq.ft./HDD.
Dayton Power and light charges 10.5 cents per KW/Hr.

As for the rest of your post, I am not sure I understand it.
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Old 06-25-2009, 04:50 PM   #19
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(another) Fair quote?


Quote:
Originally Posted by AndrewF View Post
Dayton Power and light charges 10.5 cents per KW/Hr.

As for the rest of your post, I am not sure I understand it.
For a $500 elec. bill @10.5 cents/kwh you must have used 4762 kwh during this 31 day period, or 154 kwh per 24 hr day.
Assuming this all went into heating during January '09, which averaged 43.9 Heating Degree Days per day in your location, and assuming your house is 2000 sq. ft., you used 7.8 BTU per sq. ft. per Heating Degree Day, which is slightly more lossy than the "average" residence.

This may explain your surprise at your high heating bill.

Since you have a heat pump this is a pretty high bill, unless it was so cold that the aux. heat ran most of the time. Probably it did.

As to using propane or fuel oil instead, 1 Therm of energy can be had from approx. 0.71 gal of fuel oil, 1.1 gal of propane, 29 kwh of elec heat, 8.4 kwh of heat pump heat (COP = 3.5), 4.2 kwh of heat pump heat (COP = 6.9).
What rates would you be paying for those fuels in your area?

Last edited by Yoyizit; 06-25-2009 at 04:53 PM.
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Old 06-25-2009, 05:02 PM   #20
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(another) Fair quote?


Yoz.

He has around 5,000 sq ft. Including the basement.
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Old 06-25-2009, 05:17 PM   #21
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(another) Fair quote?


Quote:
Originally Posted by beenthere View Post
Yoz.

He has around 5,000 sq ft. Including the basement.
Then he's doing quite well at 3.1 BTU, etc., etc.

1.7 least heat loss
3.1 in Dayton, OH
3.8
4.0
4.4
5.7
8.0
8.8
11 most heat loss

Histogram
0 to <3|x
3 to <6|xxxxx
6 to <9|xx
9to<12|x

Thanks, Mr. B.

Last edited by Yoyizit; 06-25-2009 at 05:24 PM.
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Old 06-25-2009, 05:32 PM   #22
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(another) Fair quote?


Actually he's not.

As I recall, his system is set up to shut off the heat pump at some outdoor temp. And only use the strip heaters.

Which is why his bill is a bit high. Probably knock off 10 to 15% of his highest heating bill if the heat pump didn't lock out.
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Old 06-25-2009, 05:39 PM   #23
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Quote:
Originally Posted by beenthere View Post
Actually he's not.

As I recall, his system is set up to shut off the heat pump at some outdoor temp. And only use the strip heaters.1

Which is why his bill is a bit high. Probably knock off 10 to 15% of his highest heating bill if the heat pump didn't lock out.
1 When the COP drops too low?
I think I'll limit my histogram to NG and/or fuel oil and/or all elec. heat.
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Old 06-25-2009, 05:41 PM   #24
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(another) Fair quote?


Nope, he has it shutting off well before a COP of .

Probably around 1.6 to 1.8 as I recalll.
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Old 06-25-2009, 05:53 PM   #25
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(another) Fair quote?


Quote:
Originally Posted by beenthere View Post
Nope, he has it shutting off well before a COP of .

Probably around 1.6 to 1.8 as I recalll.
Why so high?
http://books.google.com/books?id=A7W...esult&resnum=3
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Old 06-25-2009, 06:40 PM   #26
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(another) Fair quote?


He'll have to answer that.

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