This is an interesting point you stated, " One ton of A/C is equal to 12,000 btus/hr. and 3420 btus/hr equals 1000 watts." However, it applies to direct conversion such as resistance heating, and not to the compressor operated, gaseous to liquid, state changing, "Heat Pump," as that system, so widely used, is not converting the electrical energy into heat or cool, It is moving the heat. (By absorbing head with liquid to gas vaporization. And releasing heat by compressing the vapor, resulting in a state change to liquid and subsequently the "heat of vaporization" previously absorbed, is given off . This "heat-pumping" works for space cooling, as well as heating. The placard on my home heat pump (a unit manufactured in 1985) shows an "EER" (Energy Efficiency Rating) of 13, indicating the BTUs moved into or out of my home, only require 1/13 of the comparable electrical energy, as if used to heat the air, and the 3.5 ton only uses 945 watts, to produce 42,000 btus/hr, (Plus fan motor consumption.) of heating,or cooling, energy flow. (I agree with you other computations it is only the conversion of one ton of AC @ 12,000 btus/hr by using the 3420 btus/hr as cooling electrical energy of 1,000 watts indicating 4.7hp for a one ton ac being a possible point of confusion to which I object.)
Dennis Lee Miles (*evprofes...@evprofessor.com <evprofes...@evprofessor.com>)* * Founder: **EV Tech. Institute Inc.* *Phone #* *(863) 944-9913 (12 noon to 12 midnight Eastern US Time)* *Educating yourself, does not mean you were **stupid; it means, you are intelligent enough, **to know, that there is plenty left to learn!* * You Tube Video link: http://youtu.be/T-FVjMRVLss <http://youtu.be/T-FVjMRVLss> * On Sun, Aug 3, 2014 at 10:24 AM, Roland via EV <ev@lists.evdl.org> wrote: > Before selecting a A/C unit, a calculation of how much heat gain or lost > there is between a inside surface of a structure and the outside structure. > > One ton of A/C is equal to 12,000 bturs. > 3420 bturs equal 1000 watts. > > The formula is: bturs = SF x u factor x TD > > SF is the square foot area of the exterior surfaces > U is equal to 1/R > TD is the Temperature Difference between the temperature of the outside > surface to the inside surface. > > Calculation for a passenger compartment of a vehicle not insulated: > > Single pane class is 1 R-Factor > Single panel of sheet metal is 1 R-Factor > > Therefore the u-factor is 1/R = 1u. > > For heating loss, we use 100 F. degree temperature difference (TD) to > maintain a interior temperature of 70 F. at 30 below 0. or TD = 100 > > For A/C heat gain, we use a 70 F. degree temperature difference (TD) to > maintain a interior temperature of 70 F. at 140 F ambient or TD = 70 > > The calculation which I use for my EV: > > My SF = 175 SF of the interior passenger > The u-factor would be 1/1 or 1U if not insulated > The TD = 70 F. > > Therefore: > > Btur's = 175 SF x 1 U-factor x 70 F TD = 12250 bturs. > > One ton of A/C = 12000 btur's > > Minimum size of A/C unit will be 12250/12000 = 1.02 ton > > Adding insulation which I install two layers of 1 inch soft foam in the > door panels and firewalls. Insulated the floor with 1 inch of firm DOW > blue board foam with a layer of 1 inch soft foam and carpet. This reduce > the btur's to about half. > > Heating only takes 640 watts at 120 vac 60 hz (continuous ON) at 0 F. If > I want the heater to cycle, than I switch in another 740 watt heater. The > power comes from my rotating inverter/alternator that is rated at 7kw. > > Roland > ----- Original Message ----- > From: Jan Steinman via EV<mailto:ev@lists.evdl.org> > To: ev@lists.evdl.org<mailto:ev@lists.evdl.org> ; > ev-requ...@lists.evdl.org<mailto:ev-requ...@lists.evdl.org> > Sent: Saturday, August 02, 2014 11:22 PM > Subject: Re: [EVDL] Hybrid Mustang: AC or DC? > > > > From: Ben Goren via EV <ev@lists.evdl.org<mailto:ev@lists.evdl.org>> > > > > ... are there heat pump systems rather than compressor units that > might be more energy efficient? > > The compressor-based system in almost all consumer things that reduce > temperature *is* a heat pump. > > The only one that I know of that is different is the "Einstein > evaporator" used in many multi-powered camping refrigerators. > > :::: Rapid growth in the human energy base has broken down old > biological and cultural diversity, and simultaneously led to proliferation > of human numbers and individual diversity. The climaxing and decline of > energy will inevitably result in a reduction of human numbers, and possibly > individual diversity, while stimulating the re-emergence of localised > biological and cultural diversity. -- David Holmgren > :::: Jan Steinman, EcoReality Co-op :::: > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub< > http://www.evdl.org/help/index.html#usub> > http://lists.evdl.org/listinfo.cgi/ev-evdl.org< > http://lists.evdl.org/listinfo.cgi/ev-evdl.org> > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>) > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140803/0d01e1bc/attachment.htm > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140803/07702419/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
