The point is NOT the 15000. The point is that BTU/h != BTU
Power != energy Watts != joules Here "!=" is used in the computer language sense of "not equal" Stating the incorrectness of the label (power vs. energy confusion) is the entire point of the reference. ________________________________ From: "[email protected]" <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Wed, June 9, 2010 10:05:33 AM Subject: [USMA:47602] Re: One unit only If the SI rating is merely incidental, why even state the non-SI rating. Is the non-SI rating more than incidental? Again, why burden the readers with the numerical conversion of the rating, accurate or only orally approximate? ---- Original message ---- >Date: Wed, 9 Jun 2010 06:38:19 -0700 (PDT) >From: "John M. Steele" <[email protected]> >Subject: Re: [USMA:47590] Re: One unit only >To: [email protected], "U.S. Metric Association" <[email protected]> > > Obviously, there may be alternatives to my > viewpoint, but I felt the SI rating was incidental > to the conversation when the real issue is that the > label is completely wrong and contributes to the > confusing of power and energy. > > Of course, the BTU is as poorly and multiply defined > as the calorie. Pick a BTU, pick any BTU! However, > I would hazard a professional SWAG that the rating > relates to a fuel rating and an API method, > therefore BTU60, the value at 15.5555 °C (60 °F), > which is 1054.68 J/BTU. Of course 1 h = 3600 s, so > 15000 BTU/h x 1054.68 J/BTU x 1 h/3600 s = about > 4400 W (4394.5 W if you like "decimal dust"). > > Any other BTU would only change the result > slightly. For practical accuracy just multiply the > BTU/h value by 0.293 to get watts (in your head, > even 0.3 would suffice) > > ------------------------------------------------ > > From: "[email protected]" <[email protected]> > To: U.S. Metric Association <[email protected]> > Sent: Wed, June 9, 2010 9:07:13 AM > Subject: [USMA:47590] Re: One unit only > > John, > Although you may be forgiven(?) for quoting Jim's > non-SI value, you too do not include the power of > the gas grill in watts. What is it? Why burden the > readers to convert to SI? > Gene > p.s. I do have highest regard for the postings of > both of you relative to postings by other > subscribers in spite of this rare deviation from SI. > ---- Original message ---- > >Date: Tue, 8 Jun 2010 18:59:49 -0700 (PDT) > >From: "John M. Steele" > <[email protected]> > >Subject: [USMA:47581] Re: One unit only > >To: "U.S. Metric Association" <[email protected]> > >Cc: "U.S. Metric Association" <[email protected]> > > > > Jim, > > > > I agree with glassy-eyed and wobbly kneed, but > this > > is the ROOT of all energy vs power confusion. > > > > Just ask, "So, after the grill has consumed 15000 > > BTU, it dies? That seems like a lot of money for > a > > grill with a one hour life." > > > > I'm afraid it is up to the engineers to be > > persistent PITAs on this matter. Proud to serve. > :) > > > > > ------------------------------------------------ > > > > From: James R. Frysinger <[email protected]> > > To: [email protected] > > Cc: U.S. Metric Association <[email protected]> > > Sent: Tue, June 8, 2010 9:47:38 PM > > Subject: Re: [USMA:47579] Re: One unit only > > John, your last paragraph can be exemplified with > > the ratings that one sees posted for gas grills. > > They are usually rated as being, for example, "15 > > 000 BTU". What is meant, though, is "15 000 > Btu/h" > > -- where I have fixed the error in the symbol and > > have added the divisor. The former is an energy > > value; the latter is a power value (the rate at > > which chemical energy is converted to thermal > > energy). > > > > Caution: Experience has shown that if I try to > > discuss this with the sales staff, they get > > glassy-eyed and start to look wobbly in the > knees. > > > > Jim > > > > John M. Steele wrote: > > > Pat, > > > I'm sorry but I must go back to your statement > to > > Stan, " It seems really odd to me that engineers, > > who > > > > probably know much better, are using a > power > > unit > > > > when they are referring to energy." > > > In the instance you cite, you are talking > about > > energy over a time period, and energy divided by > > time is power. Annual energy usage has a > dimension > > of power, whether you use power units (watts) or > > explicitly describe the energy and the time > period. > > > Stan is at least technically correct in using > > watts. I have some misgivings about average > power > > vs peak power if the situation is not fully > > explained. > > > Power and energy have exactly the same > > relationship between them as velocity and > distance. > > If either is described fully as a time function, > I > > can derive the other. Since I am retired, I > drive > > much less. Pardon the miles, but they are > > unfortunately the units on my odometer. I am > only > > driving 4000 - 4500 miles per year. As there are > > 8760 hours in a common year, my average speed is > > circa 0.5 MPH. That, of course is completely > > useless as a description of my driving which is > > normally at 25 - 75 MPH, plus many hours with the > > ignition is off. My miles per annum is a speed > > (just not terrible useful). 0.5 MPH or 4400 > > miles/annum encodes the same information. > > > In the same sense 1600 PJ/annum and 50.7 GW > > encode the same information. As I don't know how > > evenly the 1600 PJ of coal is burnt over the > year, > > the utility of average power may be debatable but > it > > is technically correct. When energy usage over a > > period is described, the period is so intimately > > attached to the energy that it would be better to > > drop both units than only one. > > > I do understand that you meant petajoules per > > annum, but I believe that omitting the per annum > has > > lead to some of the confusion that has existed > here > > in various notes about energy vs. power. It must > be > > completely explicit, or at least that is my view > on > > the matter. > > >...
