DiggerJim said:
First I have to thank you for the past few days' exchanges. They have provided an exceptional case study for my son's class sessions in critical thinking.
As for your points today - I understand as a heat pump guy you might not be aware of how oil is used & projected...
While you're studying critical thinking, you might just want to study up on the dangers of making assumptions, and perhaps the benefits doing research. Heat pumps are a small fraction of my business. Most systems we install are oil, wood, or gas (in that order). My website is linked right in my signature at the bottom of every post. Perhaps you missed it?
DiggerJim said:
...but the equivalents of degree days to gallons of oil is a rather trivial exercise. (The figures I noted were from the Mass Oilheat Council using data from the National Oilheat Research Alliance.) Oil dealers do this calculation all the time -- degree days can be translated into BTUs of supplemental heating needed which can then be translated to # of gallons of oil. The oil dealers use this to determine when to come fill the tank if you're on automatic delivery. In this case the Mass OC says that the 50 degree days of Sept 07 required 1,390,000 BTUs or 10 gallons of oil (there are 139000 BTUs in a gallon of heating oil).
The term is "k-factor." It's defined as "heating degree-days per gallon." The thing is, k-factor includes the efficiency of both the system and the structure itself. Having worked for oil companies in the past, I can tell you that actual k-factors vary from 5 to 25 in probably 95% of structures.
In other words, one structure might consume 10 gallons of oil to supply heating to offset 50 degree-days, whereas another building in the same climate may have only used 2 gallons.
Apparently, you are imagining that the building in question had a k-factor of 5. From practical experience, a building like that is one which is uninsulated, with single-pane windows, massive air leaks, and an extremely inefficient heating system (probably an old coal steam boiler with an early oil-conversion burner). It does not sound like that is what the house in question is like.
And, of course, heating degree-days do not exactly correspond with energy consumption. A basic oil system will be more efficient under heavy load, so a month of warm days with a single cold day would require less fuel than a month of slightly-cool days, even if both months have identical heating degree-day numbers. A high-efficiency heat pump (or a properly-installed mod/con boiler, for that matter) will be the opposite, and operate most efficiently in the latter hypothetical month than in the former. The k-factor is a statistical number used for estimates of gross fuel consumption, not something that you can use to determine actual consumption in any given month (particularly when weather is not ideal for the given system).
There simply is no direct, universal equivalent between heating degree-days and either btus needed or gallons of oil consumed. Each structure has a different efficiency, based upon the building envelope, daily use, and the efficiency of the heating system.
DiggerJim said:
This actually helps us calculate exactly how much electric he would have used heating with pellets -- 6.8 KWH or 68 cents at 10 cents a KWH.
Interesting. Do you happen to know how much the author of that article pays for electricity, or are you using the national average blindly? I pay over 15 cents per kwh. It's entirely possible that the author of that article is paying different rates for the heat pump's power, versus the power for the rest of the house - dual-metering is common here in NH, and I have trouble imagining that electric service in Mass is so behind the times as not to allow for it.
In other words, additional power used by the heat pump may have had a small economic impact, whereas small changes in other power usage would have had larger economic impact.
I've deleted the rest of your mathematical conclusions, since it is readily apparent that they are based upon assumptions that you have made, rather than actual data. Math works great... but only when the data being used are accurate.
DiggerJim said:
My father spent a lifetime in the HVAC industry (as did my grandfather) both residential and commercial so all of us kids were kind of immersed in it from birth by the way
One thinks you would be familiar with the variability of the ratio of heating degree-days per gallon, then...
DiggerJim said:
I don't expect you'll take me up on my offer and I'm pretty much done with this thread. My only purpose lately has been to demonstrate how people will easily believe, and then blindly defend, claims that make no rational sense and are not physically possible. As I've said, it's been a very instructive example of critical thinking (or lack thereof).
You've done an
excellent job of demonstrating exactly that.
Let me know when you've met with the author of that article and done an engineering analysis of his house to determine the actual heat loss of the structure under varying weather conditions, charted out the weather for the given months (day by day, not monthly totals) and examined his electric bills to determine how many kwh those dollar values actually equate to.
Until then, you are doing an excellent job of demonstrating the principles of making and blindly defending claims without scientific validity.
Joe
One of those heat pumps with the 12.5 EER (12,500 BTUs/KWH) would have consumed 111.2 KWH and cost him $11.12 and increased his bill (after offsetting the pellet stove consumption he replaced) by $10.44 overall. To acheive his $54.69 in overall savings, his magic combo heat pump generator, generated a total of 651.2KWH (111.2 used for heat + 540 to reduce bill by $54). It's a wonder that this isn't on the front page of newspapers all over the country. 
