| Author | Message | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 537 Registered: 7-2006 Posted From: 75.210.253.228 Rating: N/A |
Last week or so you fellows had my curiosity at a high regarding Air Conditioners. I asked a question in the middle of a thread, and got a reply from Nick...but no one else; so...I'll re-ask the question>....  Do any of you use a basement A/C while driving? If so, how about some particulars.. Mine is a Coleman two compressor unit. Have never tried it while driving. BTW, Nick doesent use his while underway. Muchas Thanx. RCB | ||
| Larry & Lynne Dixon (Larry_d)
Registered Member Username: Larry_d Post Number: 193 Registered: 7-2005 Posted From: 71.111.188.44  Rating: N/A |
RC I had a Bluebird Wonderlodge which had basement air I had to run the genset but I ran at least one and sometimes two down the road as I had to keep the pug dogs cool. They did a very good job. Larry | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 975 Registered: 12-2000 Posted From: 71.54.29.215  Rating: N/A |
I think we have the same Coleman basement AC as yours. We use it while driving and it works great. We run it off the generator (our inverter is not big enough). Our front most AC duct is in the center of the ceiling about 2' behind the driver's seat. We keep this vent aimed towards the top of the windshield. We have 2 small 12 volt fans that re-direct this air onto us. Only time we notice any lack of cooling is if we are heading west at about 3 PM. Just so much radiant heat coming in through the windshield. We still feel the cool air, but also the radiant heat. Jack | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 543 Registered: 7-2006 Posted From: 75.211.63.169 Rating: N/A |
Thanx, Larry and Jack.... The reason I am curious is that the threads lately seem to tell that the alternator, if large enuf, will keep the A/C running AS LONG AS one is driving...that the charging will put plenty into an inverter to do it. Could be I am just doing some wishful thinking. We have our Coleman wired so that it is completely outside the inverter. Either the Genset or Shore Power required. Come to think of it, I believe that even the genset (ours is a 6.5 KW), according to Coleman info, will not turn on the second compressor. I haven't tried running the Generator while driving....seems redundant under most circumstances....and in the past year or two, seems plain $$ foolish. We have a Crown Coach..amidships engine, which means directly under the floor...which means lotsa' heat coming up thru the floor. The cork sheets help. but on a long trip...all day drive, that doesn't mean much...Everything heats up. Consequently, I am thinking about the POSSIBILITY of trying a run thru the alternator. Comments, suggestions, criticism (gently put, please ) welcome.... I KNOW there must be a way....before I spend $$$ on a driver's A/C unit. ...in which case, I'll be asking more questions. "Wonerful, wonerful" BNO....thanx Ian, et al. RCB | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 70 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
My transit has a 300amp Delco 50DN direct drive alternator. At 14 volts running, that's putting out 4200 watts max-which could run two A/C's at the same time. Since any surge in starting will just use the batteries as backup, running wattage is what you have to worry about with an inverter system-so the batteries won't eventually get discharged. Good Luck, TomC | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 978 Registered: 12-2000 Posted From: 71.54.29.215 Rating: N/A |
I was told by someone, or read on one of the BB's that an alternator running at max output requires about 20-25 HP. I was also told that 1 gallon of diesel fuel will produce about 17 HP for 1 hour. If those facts are correct you are going to use about 1 gallon of diesel per hour to create the required HP for the alternator. AND, that is 20-25 engine HP that is not available to push your coach up that steep hill. Our PowerTech 8 KW generator uses about .3-.4 GPH. Our previous generator an Onan gasoline 6.5 used about .8 GPH. We frequently ran both compressors of our basement AC using the Onan 6.5 KW. Jack | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1511 Registered: 12-2000 Posted From: 76.66.16.38  Rating: N/A |
Jack, you may be remembering the popular suggestion that a stock coach AC unit will consume 20-25 HP, AC compressor and alternator combined load on the engine? Fully loaded alternator, running those big electric fans would be part of that, big compressor the other. happy coaching! buswarrior | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 61 Registered: 1-2009 Posted From: 24.129.235.190  Rating: N/A |
that sounds more like the facts buswarrior, I recall looking up the specs for the O5G A/C compressor in my MC 8, it was rated as 5 hp to 15 hp consumption depending on the load demand. The oil cooled DN50 would be about 9 hp at 6 kw full output, so a maximum of 25 horsepower but not at the jimmies 900 foot pounds of torque , more like at 40 foot lbs. So the true draw on the "go down the road engine" is a little fuzzier than simply suggested back there in those archives; if I care to recall those heated threads from several years back when I was proposing to run the factory AC of it's own source of "motivation". ahwck now, I am coming down with "booed busnut post traumatic proposer stress" and hearing "impossible" ringing in my ears, time to clime into that box were not to think outside of and go back to sleep before one of the "experts" chime in! | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 983 Registered: 12-2000 Posted From: 71.54.29.215 Rating: N/A |
BusWarrior, Thanks for setting me straight. Seems my memory is a ittle fuzzier than it used to be. Jack Remimder to self: Self, DO NO TYPE UNTIL MORNING COFFEE IS FULLY CONSUMED!! | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1513 Registered: 12-2000 Posted From: 76.71.100.117 Rating: N/A |
We gotta stick together, between us all, we'll keep the stuff straight. A shared collective memory, each of us a little right, and I for one, a whole lot forgetful!!! As long as we're smiling....! happy coaching! buswarrior | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 62 Registered: 1-2009 Posted From: 24.129.235.190 Rating: N/A |
...tis yet another fact BW, if we expect to create our collective potential | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 747 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
If we did more truth finding, and less truth hunting, we would find find the electrical FACT that 1 horsepower = 746 Watts. This has been published for over 200 years! So, 6000 Watts divided by 746 would require 8.04 Horsepower. The next hundred year old published FACT is that 1 Ton of A/C = 12,000 BTU. So, two 13,500 BTU roof airs are 2.25 Tons, total. If these rooftops are only 10 SEER, which is fairly low efficiency, they would require 2700 Watts. Most bus OTR air is 5-7 Tons, AND the compressor has NO electrical loss, plus capacity control to reduce load when the bus is cool. So, a 5 Ton bus compressor, fully loaded, will consume no more than 8 hp. The next part is really tough, we have to LOOK at the horesepower rating on the evaporator fan and the condenser fan motors, and add that to the 8-10 hp compressor horsepower requirement. Obviously, that number won't be more than TWELVE. 200 Amps out of a 50DN alternator at 14 Volts will require 3.75 Horsepower. When you are going downhill, engine driven A/C is FREE! G | ||
| gary throneberry (Garhawk)
Registered Member Username: Garhawk Post Number: 19 Registered: 3-2007 Posted From: 68.19.252.30 Rating: N/A |
hi r.c. my rts has 2 stage, dual compressor, coleman unit. plan to run the unit down the road from engine 24v altenator, thru battery bank, and thru 4000 zantrex inverter. will keep unit to stage 1 only. meaning only one compressor working. don't know how to accurately compare financial difference in running our ac units in this fashion as opposed to using the outboard generator. however, it seems to me the wear and tear on a seperate engine has been ignored. also, my impression from naysayers is that their figures are calculated by using constant running terms for the compressor and continual drain back thru the inverter, battery bank, to alternator. as we all know, that is not the case, compressor runs, shuts down, restarts, ad infinium. believe that is called cycling. my feeble reasoning says that the battery bank, being the buffer, smooths out the demand and delivery thru the inverter. perhaps one of our resident experts can study the dynamics of this question and, report to us in a more factual method - considering ALL the issues. somehow, running two engines to accomplish what one can deliver just doesn't square up. if that not be the case, excuse me and, one more change in the conversion will be in order. gary t'berry rts '89 102 40er | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 545 Registered: 7-2006 Posted From: 75.209.117.10 Rating: N/A |
George...you addressed the on board A/C issue...but what can I offer in the way of information to make...or not...the case for my original question.? Gary...thanx for the input. Your scenario is more or less what I have pondered over the years...but have been dilatory in dealing with it Thanx to all for the words and thoughts...keep it coming. We may be able to solve the all the problems of the USA if we keep this up!!! alas, then who would need a PRESIDENT and Congress...  . TCB | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 304 Registered: 1-2005 Posted From: 76.246.252.104 Rating: N/A |
George, Thanks for the math. It confirms my plan of front roof A/C running on inverter with switch over to generator capability for freeway stop-and-go, and city driving. And those times we check in and the park wants engine and generator turned off. Rear A/C will always be gen or shore. Jack, I was also planning on mounting one or two fans to augment the front air when driving. Did you mount yours high or low in relation to windshield? Is one or both pointed directly at you? Would you do something else if doing it again? Thanks. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 984 Registered: 12-2000 Posted From: 71.54.29.215 Rating: N/A |
George, Thanks for the math, gives a much better understanding. Chuck, The fans are installed above the windshield. One blows directly on me and one on my wife. We each have our own 2 speed fan switch. I would do it the same id doing it again. We are very pleased with our set up. We did follow the manufacturers recommendations to the letter as far as duct size and installation procedure. Jack | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 63 Registered: 1-2009 Posted From: 24.129.235.190 Rating: N/A |
MCgeorgeSIX I had begun to worry you had indigestion from all those veggies you hinted you had been doing; suspected my discrete and non-directional whit might motivate you. I don't know if it's a "Birds of a feather" thing or that I like looking in a mirror of a earlier less detailed oriented version of myself, not to suggest that you that you might end up as I or anything like that, nor that there is anything wrong with that either my learnid friend ! | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 546 Registered: 7-2006 Posted From: 75.209.117.10 Rating: N/A |
George...you addressed the on board A/C issue...but what can I offer in the way of information to make...or not...the case for my original question.? Gary...thanx for the input. Your scenario is more or less what I have pondered over the years...but have been dilatory in dealing with it Thanx to all for the words and thoughts...keep it coming. We may be able to solve the all the problems of the USA if we keep this up!!! alas, then who would need a PRESIDENT and Congress... . Clint....is the the Queen's English you use?? Makes me wee brain tired to decipher...sometymes. RCB (Message edited by chuckllb on March 08, 2009) | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 187 Registered: 1-2007 Posted From: 208.81.157.90  Rating: N/A |
RCB Unless I missed it somewhere you have not said what you have for alternator output. Makes a big difference whether you can support running the AC from an inverter. Maybe everyone else knows what a Crown has, but not me. As far as running both compressors from your generator, a 6.5 KW gives you better than 50 Amps. So anything you can do on a 30 Amp pole you should be able to easily do on the genny. Does than mean you can start both compressors at the same instant with the water heater cycled on, probably not. While it is not at the top of my list for wants, engine driven dash AC sure would be nice. Just going to wait and see if running the house air will do the job with better insulation in the new bus. Old bus struggled with only one rooftop and lousy insulation. Don 4107 | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 64 Registered: 1-2009 Posted From: 24.129.235.190 Rating: N/A |
...no dear Bishop, they are my words and not some Queen's "eng-leash",( I tend not to use anything any queen owns and she had best not be thinking she owns anything of me to use; this way we "owe neither nothing" !) or I mean "I use what works best for me" ! Perhaps give your brain the credit I do and all that ciphering may need not be employed, which does leave your brain freer to create my friend. Back to what I was going to type before I was interrupted by the dogs going exploring without me; the main concerns I would look to address your concerns ... most important .is your model of coleman split A/C system physically designed & up to the task of operating while bouncing down the road without damage or accelerated wear & tear ? ..will my chassi alternator, with an invertor operated both compressors or will I just be able to use it for one and have to run the house generator for peak loads such as initial cool down and extreme ambient conditions or just plain old "too much sun in my eyes" while driving . I would have to answer dozens of other detailed questions to provide relevant data to make a meaningful complete cost comparison analysis that would encompass all aspects such as wear and tear, fuel consumption efficiency to expect anything beyond a educated guess. Even if I could answer all the prescribed questions for informed decision making, the bottom decision line is likely to be convenience and redundancy for the bucks available as like most passions "or/a" needs, the more I have available, the more I shall invest in it until the passion is no worth the effort required or I can no longer afford it. I do know that country coach has employed similar cooling strategy with similar configurations for road A/C modes (with rooftop HAVC & smaller chassi alternators), so it is has work for there concerns, not that this means there concerns or configuration are comparable to yours. | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 273 Registered: 2-2006 Posted From: 75.199.212.204  Rating: N/A |
Well, I have to chime in here now.. There is a reason why all the big coach converters utilize the chassis A/C system. IT WORKS! and well. Two years ago, my condencer fan motor died. "Thanks to Jack for my replacement!" This is where my redundant thinking came in handy. I was still able to have some cooling on a very hot ride to OH by using my house A/C system. Granted, it was nowhere close to cooling the coach with 95 deg. temps and climbibg some big hills but, it was something. I still can't believe that alot of folks tear out the chassis systems..?? To Each His Own! Oh, George, my book says that my 04G comp is rated at 11 tons. Hummm. ?? Nick- | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 136 Registered: 10-2006 Posted From: 72.127.92.212 Rating: N/A |
Thank you Nick for that responce. Prevo OTR a/c compressor is 10ton, 75thou btu. Why would you remove that. That is almost double the capacity of all 3 of our cruseairs combined. It will keep 50 very overweight people cold on a 95 degree day. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 548 Registered: 7-2006 Posted From: 75.209.117.233 Rating: N/A |
So...Nick... My understanding was that you DID NOT use your basement A/C.. ("OH"?)...or? RCB | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 748 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Nick, Mine is rated 9 Tons, and has 2 stages of unloaders. I suppose that rating is at 2100 engine rpm? (Never had any trouble guessing the rating of an electric compressor!!) Regards, George | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 274 Registered: 2-2006 Posted From: 75.196.153.161 Rating: N/A |
George, Yea, I know what you mean... Chuck, Yea, I used my basement A/C when the OTR cond. fan motor died. on a trip to Ohio. Joe, I'm with ya... I think the problem is repair/ upkeep costs for some. Nick- | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 749 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Now we know why Clint thinks DC air conditioners are great. (He has DC generators.) Now all he has to do is buy a BIG 24V charger to run his airs while parked on shore. Then an inverter to run the rest of his household stuff while boondodcking. I haven't fertilized the back yard yet... G | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 67 Registered: 1-2009 Posted From: 24.129.235.190 Rating: N/A |
...while please do get to it (the back yard duties) Mcgorgethesixth , holding in all those veggies for to long will make you flatulent and may have unintended influences on your posting ability ; or so I have found of my own physiology ! I guess i could apologize for not re-stating, a few more times, my many motives for contemplating and exploring the pro's & con's of a 24 vdc design, which includes the majority of consumption apparatus. But all the details would also likely encourage some to feel offended , so we just do it our way and apologize for nothing (as you can't really hear farts on BNO) . With time and interest the truth is generally accessible to those that look for it (it is the only thing I still hunt for despite being a Hunter by name). Which you seem to already understand most of the time, but that is just my assumption ! uhm...I have already those big chargers left over from some electric pallet jacks along with some high quality U.P.S.es from computer mainframes, so you can see part of the pathology of "junk, junk, what shall I do with all this junk". | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 549 Registered: 7-2006 Posted From: 70.210.239.73 Rating: N/A |
Boys...boys....come back to earth..... | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 750 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
See RC, Now I have fertilizer! D & J, As posted on 3/08, a ton of air conditioning is 12,000 BTU. (This is the amount of heat required to melt a ton of ice.) 10 tons is 120,000 BTU. Regards, George | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1359 Registered: 10-2003 Posted From: 71.58.110.9  Rating: N/A |
I've been following these over the road AC setups for the last few years. I am/was planning to run mine through the Alt/ inverters/ batteries also. But the more I think of it: load and wear on that gear driven alternator; mostly if the drive system fails and those pieces go through the engine gear train-????, charge/ discharge on those house batteries, replacement and adding water, wear and tear on the inverter, etc. VS just running the diesel generator to accomplish this job. I don't think wearing out that noisemaker is going to be an issue. How many years is it going to take to accumulate 5000 plus hours? We usually don't use them enough to justify the cost. Those diesel generators are easy on fuel. With a separate tank, you could run the cheaper untaxed fuel in it. using the coach engine to do this is going to use, at least/ probably as much additional fuel, and unless you are running a 92 or a 60 series rob power that is better needed for going down the road and especially up the hills.And that alternator is going to dump more heat into the engine cooling system through it's oil cooling, especially at full tilt. Just food for thought and what I'm starting to lean towards. BTW, that white background behind the words I posted is ABC powder to inhibit/ discourage flames. | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 68 Registered: 1-2009 Posted From: 24.129.235.190 Rating: N/A |
,,,great to hear bigG, now it is just a matter of planting those seeds we keep sending your, to uhmmmm germinate as I suspect this may be the last time the Bishop uses as open a sub title as "on the go" | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 552 Registered: 7-2006 Posted From: 75.210.37.147 Rating: N/A |
....then again,everything usually comes out alright....in the end. Wonder if they have Keopectate for the fingers... Scheeesh. Wha' happened to the subject? RCB | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 70 Registered: 1-2009 Posted From: 24.129.235.190 Rating: N/A |
!!!! even these threads of knowledge are prone to intermission filled with commercials and propaganda during this age. I for one could recommend the nostrils , one hole to deal with each cluster of fingers and the typing stops right up, just breath through the mouth. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 721 Registered: 10-2006 Posted From: 66.82.9.16 Rating: N/A |
"using the coach engine to do this is going to "use, at least/ probably as much additional fuel, and unless you are running a 92 or a 60 series rob power that is better needed for going down the road and especially up the hills." I would wonder at the engines condition if creating an extra 5 HP is going to overheat it or slow hillclimbing any noticable amount. yrmv FF | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1514 Registered: 12-2000 Posted From: 76.69.142.83 Rating: N/A |
oh boy.... On the older MCI, the two fan motors for inside and the condenser typically add up to 3 horsepower, as rated. Two roof airs run through an inverter going down the road will draw pretty much the same electricity as the big fans, so the stock alternator won't know the difference. That 20 HP figure for the HVAC system has floated around for a long time. George, did you figure in some waste for the inefficiencies? I'll suggest from my own fooling around, both in my own bus and loaded seated coaches back in those days, that in a blind test, you'll not be able to tell if the HVAC is on or off when pulling a long climb, you can't feel a change in climbing power. So in practice, does it matter? happy coaching! buswarrior | ||
| Cullen Newsom (Cullennewsom)
Registered Member Username: Cullennewsom Post Number: 29 Registered: 2-2009 Posted From: 129.7.53.155 Rating: N/A |
My Neoplan has a huge Thermo King / Sütrak system. I have fancy daydreams about running it when my coach engine is off. I guess I could get another 6V92TA and mount it on top of the old one to run the A/C. I'm not sure if anyone would let me park next to them. ;oD -Cullen | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1362 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
Bus warrior... I beg to differ. The coach is going to get warmer inside. | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 907 Registered: 11-2004 Posted From: 173.78.29.189 Rating: N/A |
Posted on Sunday, April 30, 2006 - 2:58 am: -------------------------------------------------------------------------------- I think some people are getting confused about compressor HP and btu/hrs - let me see if I can confuse it more - The btu's you are discussing are "cooling capacity" btu's - not the number of btu/hr or HP needed to drive the compressor Using 1 HP = 2540 btu/hr Then taking a "cooling capacity" of 76,200 btu/hr (6+ tons) You first have to figure the "coefficient of performance" - this is the efficiency attained in actual 'cooling' by a particular refrigeration system - late model compressors are capable of achieving a factor of up to 3 A cooling capacity of 76,200 btu/hr with a "coefficient of performance" factor of 3 would require 25,400 btu/hr or 10 HP Furthermore a compressor which unloads to 33% after the initial 'cool down' would only require 3.3 HP *** DISCLAIMER (yes, this is for newer efficiency units operating at 100% efficiency - I am not commenting on the take it out/ leave it in discussion - only trying to clarify the actual loads placed on the mill - and yes I know the motors add more load via the alternator - but the COMPRESSOR ITSELF is more accurately a 5-15 HP load plus any inefficiencies in a 9 ton system) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 755 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
BW, What I did was to take the electrical constant of 746 Watts per horsepower, and multiply that by the old minimum standard efficiency rating of 10 SEER. (Seasonal Energy Efficiency Ratio) A 10 SEER 5 Ton electric unit (60,000 BTU) whether some like it or not, will consume 6000 Watts. Divide 6000 Watts by 746, and you get 8.04 Horsepower required. The proper efficiency measurement requires adding back the heat given off by the furnace or evaporator motor, which is in the conditioned air stream. Of course there is an electric condenser fan, and the electric compressor. Now, we go to a bus, with an electric evaporator motor, either an electric or shaft driven condenser fan, depending on brand, and an engine driven compressor. In a bus, air conditioning capacity is a function of engine speed, a problem not faced with electric compressors. An electric compressor motor is cooled by the returning Freon, so that heat must be rejected by the condenser, in addition to the indoor heat. Personally I think a shaft/belt driven compressor would be more efficient than an electric compressor driven by a seperate engine driven generator. Then you've got to figure in another radiator fan and water pump, and electric losses in both the gen and comp. Interestingly enough, as posted immediately above, a 76,200 BTU system at 10 EER, the way I figured it, requires 10.2 HP. I appreciate Niles' validation of my figures, we both took different paths, and came up with the same numbers. Main engine driven A/C, whether belt or alternator driven, is free whenever the bus is decelerating. Look also at Sean's post in the concurrent thread on roof airs running on a 30 Amp park service! Keep cool, George |