| Author | Message | ||
| Steve Zona (Highwayrunner)
Rating: N/A |
Hi guys. we are quite new here and have only had our mc9 for about two months, and are still debating .roof airs versus basement air. today after pulling the bulkhead in the front bay, to get a look at where a basement unit might be placed. I started to wonder... a dangerous thing all by itself. does any one know if is possible, or just plain insane, to remove the bus over the road ac compressor, and replace it with a 110 volt ac type compressor. and at the same time . change the other 24 volt blower and fan over to 110ac type units, so far the groups info has been great. when you all stop laughing, any advice would be appreciated. | ||
| John that newguy Rating: N/A |
You'll be hard-pressed to find a single 110v air conditioner that will do the job. I don't believe any exist that run on less than 220v. I fought the same battle. I finally gave in, and am taking out the bus ac and going to roof airs. When you take a close look at what's inside that bus ducting, you'll wish you were anyplace else. And.... the un-insulated bus floor ducting is extremely inefficient. My bus system worked when I bought it last year. It does not, now. Refilling it with freon will cost at least half of what a new roof air would cost. | ||
| Cliff (Floridacracker)
Rating: N/A |
Steve, The debate over roof or basement air will no doubt never end. I am going with the roof airs. My brother owns his own a/c buisness and I could get a free unit, but I want the roof airs for redundancy. It just came down to me that a single point of failure on an important subsystem in June, July or August was unacceptable. There is no wrong way to go on this, its just your choice. Cliff | ||
| Bill Glenn
Rating: N/A |
Hi Steve, Welcome to The Madness Two months, Mci 9 , A.C. . Well, glad to see you thinking outside the box. Jtng is right on the fact that we can only find 110v units that put out about 12,000 btu. (trying to match existing, old, evaporators to smaller compressors, and expansion valves, etc. is quite a task) The originally designed system is probably capable of 7 times that amount. 12,000 btu, On a well insulated bus would hardly make anyone comfortable, even on an 80 degree day, no less the norm on where I want to be at times. YMMV Anyway. Good safe bet with F.C.'s advice, roof airs are plentifull and cheap. (all is relative) I hate that unit on my roof,Butttt. Basement airs can be a great system if ducted properly to the areas you need A.C.. "There is no wrong way to go on this, its just your choice. Cliff" I can't say it any better. We are plumbing a combination, 24,000 btu dash air and 12,000 btu ductable bath, bed, salon air, driven off the main Detroit engine, as well as driven directly by the 12v diesel (compression ignition engine, running on waste vegetable oil)generator engine using a pair of York recriprocal compressors. Outside the box ? Efficiency is what it is all about isn't it? We also installed a roof air to take advantage of easily available 110v where appropriate, as well as a backup. Good luck with your choices, To each there own. Bill | ||
| John Jewett (Jayjay)
Rating: N/A |
BRV Products, and Carrier have excellent 110VAC, 25,000 BTU, basement air conditioner/heatpumps. And they will NEVER leak and ruin the carpet, or leave mildew and fungus stains on the ceiling! I like mine! Cheers...JJ | ||
| John that newguy Rating: N/A |
25k btu doesn't come close to the original bus air system, John. Aside from the fact the poster asked, is it possible to: "remove the bus over the road ac compressor, and replace it with a 110 volt ac type compressor". To that, the answer is a very definite no. The bus AC is about 7 ton and requires a massive amount of power. You just can't get that much power from a 110v motor or compressor. Aim lower next time, willya'? *BLAM* | ||
| RJ Long (Rjlong)
Rating: N/A |
MC-9 A/C was rated at 9 tons originally. NJT's might be more. Later model "A" series bumped that up to 12 tons. Not sure what today's new E, D & Js have. Trivia: OEM main A/C blower moved 2,750 cfm using a 1.5 hp 24vdc fan. Dash a/c blower pumped out an additional 430 cfm for a total of 3180 cfm. Designed to keep interior at 70 with outside ambient of 100. Condensor used 2 hp 24vdc fan. 'Nuff fer now. . . | ||
| Stan Rating: N/A |
RJ: Of course you are talking about old air handling technology. That entire system could now be replaced with one 3200 cfm fan from Zirco using only 1/3 HP.(grin) | ||
| dug Rating: N/A |
Basement or rooftop, ducted is a really nice way to go. Helps with noise, and is much more efficient to put air where you want it. Basement air is much quieter, which makes conversation easier. However, my wife doesn't like to hear every pop and crack outside when she sleeps. There is no wrong decision, or right for that matter. Enjoy the journey! Dug 75 MC8 Arcadia, FL | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello Steve. You can do anything you like, the trick is finding accurate and experienced advice. You know, it would be nice to hear from an AC engineer who knows their stuff, as to the variables one could play with using the existing parts. For instance: 1) If one was to plumb a smaller compressor into the big condenser and evaporator, would it work, what adjustments to fan speeds or ??? to make it work? 2) How about two compressors, the stock engine driven one, and then a smaller one for stationary use? 3) How about removing the conversion losses and driving an AC compressor directly by the genset engine, and building it from there? 4) What other creative ideas might a person who knows what they are doing come up with? Of course, we'd tell this person they didn't know what they were talking about.... there are boring off the shelf solutions, aren't you a fool for trying to do something different, and then they'd leave. Not too smart are we sometimes. :-( happy coaching! buswarrior | ||
| niles steckbauer (Niles500)
Rating: N/A |
Hi BW - my house system is an RVAC - with a unique design (and one unique parts supplier) - Housed in 1 basement package system with 2 compressors using the same evaporator, condensor and 2 speed blower - the evaporator and condensor share the coils in an "X" pattern - the system is designed for when you have limited shore power (inverter not in use) of 30 or less amps it will use 1 compressor and if adequate juice exists it uses both - but unlike roof air or cruise air units where you may only have power for one unit and therefore zoned A/C, you get equal cooling throughout the bus with the single system - the other thing about it is the high pressure it operates with (hi/lo = 300/150) makes for a very efficient system each compressor is supposedly rated at almost 2 and 1/2 tons yet each draws only 13 amps - Niles | ||
| Marc Bourget Rating: N/A |
Why would a "smart guy" A/C (Mechanical) Engineer suffer the exposure you suggest? A/C design is most efficient when constructed according to those "boring rules". Efficiency is preferred, if not necessary, especially when installed in the limited space of a bay or roof top "packet", because conversions "demand" maximum performance. A/C works on change of phase states which are best coordinated according to those rules of physics. There's lots of creative solutions, but to work efficiently and properly they must follow those unchanging rules of physics. Dave Smead's books have an excellent discussion, covering more than one chapter, on how AC's work and how to design, build, control and size an A/C unit. You'll have to buy the book, unfortunately. Onward and Upward | ||
| R.C.Bishop
Rating: N/A |
JJ....I like mine, too.  ....Via Ron the busnut. Thanx, Ron!! FWIW RCB '64 Crown Supercoach (HWC) | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Efficiency and performance are two words that require definition and context. May we agree that the purpose of air conditioning is to make some cold in the bus when it is hot outside? If it is cold in the bus, whatever the AC system looks like, it is working and many of us might not care about the rest of the equation. If one has free parts, and finds some more cheap parts to add, and can make it produce cold air, that sounds good. Now, the sizings/balance might not match well, the power consumption is high, the evaporator freezes up when it is run when it is too cool out, it can't pull down the temps if it is left turned off for half the day, that matters to some others. But if it blows some cold air.... does it matter? Hard to find someone to work on "can do". Easy to find someone to say "cannot" happy coaching! buswarrior | ||
| John that newguy Rating: N/A |
buswarrior- Anything can be done. It's just a matter of the amount of money available to experiment, and the amount of time available to be without cool air. I personally, have little of either. So I come here to see what others have found to be viable and cost-effective. Roof air conditioners are probably the best choice for those in my situation. Fairly common, easy to get used or new, and fairly easy to install and replace.... and the least expensive. | ||
| Lin Rating: N/A |
When comparing your AC needs to that of the original bus, just remember that the passenger body heat in the original bus must of needed at least 3 tons of cooling. I assume you will have less people on board. | ||
| David Hartley (Drdave)
Rating: N/A |
5,000 btu per person standard factor is used to calculate cooling in many buildings. | ||
| Marc Bourget Rating: N/A |
Standard HVAC texts define efficiency and performance and I defer to them. We agree on the general purpose, but IMHO, the term "general purpose" is of little value to resolve the point - no more than the paper it takes to print the phrase. Adapting "Free parts", depending what amount you violate the physical laws I referenced, IMHO, constitute a waste of time and money. For the most part, the effort put into adapting un-coordinated parts uses up more time than the expense saved - Unless you're lucky and your time is worth less than $5.00/hr. (US or CN)- in which case you couldn't afford a bus, much less an A/C system. Anybody who invests a little time in education, I warrant will save alot more in time and $$. You're free to run sewing machine oil in your DD just because somebody gave you a 55 gal. drum. I's sure it'll spin when you first start it up, only time will tell whether it will "matter". Paraphrasing my two posts, "Do it once, do it right and never (seldom?) have to do it again" Considering the amount of effort put into earning vacations or retirement, it's penny wise nd pound foolish to willy-nilly toss things together. My wish would be for all converters to have coaches that never need anything besides PM, they get 15+ MPG, etc., etc., and only have to drive in jurisdictions that don't require a CDL (ROFL!!!) | ||
| Lin
Rating: N/A |
I think that's about 500 BTU's per person (roughly half in heat and half in moisture), not 5000. You'd probably have to have an amazing diet to put out 5000 BTU's. You could also get your family to melt the snow on your walk rather than shoveling it. Actually, I have heard of Tibetan monks that sit in the snow and compete to see who can melt the biggest circle around them! | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Ian's old post seems to be pertinent again, so I'll re-link it here: http://www.busnut.com/bbs/messages/233/7288.html Still, free to all who are curious... Remember: 12,000 BTU = 1 Ton. 1 Watt Consumed = 3.41 BTU Waste Heat (typical electronics) And you still need to exchange air to keep people healthy... I'm working with my Uncle who was a Carrier Mechanical Engineer for 35 years, and is now retired, but still doing consulting work. I'll have a new version of this spreadsheet out later next month with WAY more advanced math... (Bus Nut = Can't leave anything alone...) Cheers! Tim P.S. Old link for free Microsoft Excel Viewer is broken on that post, use this link: http://www.microsoft.com/downloads/details.aspx?FamilyID=c8378bf4-996c-4569-b547-75edbd03aaf0&DisplayLang=en -T | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Oh yeah, Lin... 5K BTU isn't that far fetched if you're a young strapping lad and/or lady(s) who's err... being *naughty*. But that can't last more than 4-5 hours... Tops. (without "outside" assistance) Cheers! Tim | ||
| John that nudeguy Rating: N/A |
Can I be of help with the outside assitance? | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Uh... I was referring to "Chemical" outside assistance (aka. Viagra, Lavitra, a good line of coke and a bottle of whiskey). But there's room on most busses for *cough* more (now, now... fluffers don't count!) Tim P.S. By the way (Ian will give me a swift shot to the nuts if I don't mention this...) I do not condone nor advocate the use of illegal/mind altering substances (I'm not referring to the whiskey of course). I also do not suggest that young people begin mixing "intercourse" with viagra or lavitra (trade marks of their respective companies...) as you'll run out of new things to do too quickly. This post will self destruct in two or three hours... Whenever bossnut gets done pulling his hair out. - Tim | ||
| Jtng Rating: N/A |
HAR!!! Nice work, Tim! | ||
| FAST FRED Rating: N/A |
Busses have a far higher glass (the windows) content than box houses , and its the Glass that creates Havoc with the prediction numbers for the HVAC. Sometimes its easier to toss the computer and slide rule , and just look & see what others have found to work, for similar situations. FAST FRED | ||
| Buswarrior (Buswarrior)
Rating: N/A |
My apologies for encouraging experimentation and learned input, and seeking possibly cheaper ways to a solution that is acceptable to the crafty, time on his hands decision maker. I thought some busnuts liked to tinker, weren't afraid to try stuff that might not work, with a chance of discovering something new that will work. A V8 engine in a car is not efficient for most of the driving we do, it runs throttled way back, using only a portion of its power. No one else curious if the stock AC could be run the same way? happy coaching! buswarrior | ||
| Frank allen Rating: N/A |
keep in mind that the orig set up is large because it is designed to cool a full load of passengers on the hottest day, when used as a conversion you dont need all the btu s because the passengers are much less, i have a 4106 and i installed a engine driven set up consisting of a single car compresser a single condenser driving two evaporators that are street rod type , one in the front one in the rear, they are 22500 btu each, we rarely have to run em both, one time when the temp outside was 105 and we had 7 people on board we had to start the gen set and run the roof airs a short time , but that is rare, this has worked well for me, rarely ever start the gen set on the road. I like the roof airs because heat rises and i think they are more efficiant than the basement air, also easyer to replace if things go wrong , we only need to run one roof air at night. But the engine driven set ip is the best thing i ever did since i believe gen sets running can be dangerous on the road. had a fire once with a deisel set going down the road when it developed a fuel leak and soked the walls of the compartment with diesel fuel, nearly lost the coach. anyway thats my 2 cents, a 40 ft bus will probly need more like three units on top and if i instlled the engine driven set up in a 40 ft id use two car compressers and one big condenser and three evaporators Frank Allen 4106 | ||
| Guy Schroeder (Mciguy)
Rating: N/A |
Hi All, First, let me briefly introduce myself. My name really is Guy and I'm the proud, relatively new (and quite probably insane) owner of a '73 MC-8 of dubious condition which I have grand visions of turning into a luxurious, rolling retirement home. Being in the very early stages, I've been lurking here for 6 months or so, reading current threads, searching archives and chasing links on subjects that are important to me, especially those that that are not easily changeable once committed. There is a tremendous wealth of knowledge here and I, for one, welcome the diverse opinions and am not really worried that I will get worthless advice, as there appear to be many who will call the erroneous poster to task. I even enjoy the flame wars to a degree (where is 2D and the fan test?). That being said, the purpose of this post was to present an off-the-wall A/C idea that I've been toying with. As Busswarior said earlier in the thread: . . 4) What other creative ideas might a person who knows what they are doing come up with? . . Well, I don't know what I'm doing, but I'm a dreamer and inventor wannabe, so I thought I'd throw out the idea and see what the experts think. First the lead-in. I read all the pros-cons about rooftop (hate'em .. ugly roof warts), basement and split units, blah, blah. The only thing I'm certain of is that the bus system will come out. I agree with comments about running genset on the road. Don't wanna, period. Want to be cool when boondocking with minimal noisemaker use. Don't really want to carry propane for small quiet, genset. Diesels stink too much and not suited for low output, etc. So, in view of all that, I thought about energy use and how much less is required by evaporator type refrigerator. (my Stick & staple rv frige used a flame the size of most pilot lights) and in conventional A/C it is the compressor that is the energy hog. As a result, I went to my favorite starting point for tech research www.howstuffworks.com (no affiliation, just a great site). As a result, I decided to spend some effort in determining the feasibility of using several (3-?) small evaporative units distributed throughout the bus. They would be powered with either 12V or 110 (for me, no propane) which should not overly tax the batteries, localized units means you don't have to move a high volume of cooled/return air for a long distance and fans will be smaller. quieter and take less power also. My source for units would be junk RV friges and repaired as needed. Anyway, the only drawback I can see is that from my limited understanding, these must be mounted vertically, with the heat tank on the bottom, the condenser above and the evaporator above that, which will present some challenges in mounting, ducting and a use of space much larger than conventional, but I'm willing to live with that if the concept and economics are feasible. OK experts (and those with just an opinion), please fire away. Again, thank you all, Guy | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Danfoss makes most of the small DC compressors I've seen. They are used in small RV refers to Marine/Highway A/Cs. You should check out their website: http://www.danfoss.com/Products/ProductFinder/ProductFinder.htm?segment=RA&category=http%3 a%2f%2fwww.ra.danfoss.com%2fra%2fProducts%2fProductCatalogue.asp%3fNavigation%3dHideOnAllP ages%26Footer%3dHideonallpages%26Division%3dCC%26HL%3d1%26TopViewItem%3d74%26AppID%3d%7bc2 a95dac-5e01-47df-92cd-5972d837cf1a%7d Look at "Direct Current Compressors". You can take a spec sheet to an A/C guy and he can use the numbers to spec you a functional system for your application. I'm using SEVERAL compressors to acheive my insane goals (don't ask...) Cheers! Tim | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Meant to add the following as a P.S.: West Marine caries the Coolmatic series (under the "Waeco Adler Barbour" brand) compressors with condensers already attached see: http://www.westmarine.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10001&storeI d=10001&categoryId=602&langId=-1&subdeptNum=230&storeNum=15&sortBy=man&sortOrder=asc&seq=1 5 or http://www.waecoadlerbarbour.com/ and http://www.waecoadlerbarbour.com/page.asp?page=50seriescooling I hear that these are the same compressors that are being used (with a different label) as the DC-Airco brand air conditioners that Jim in California mentioned in his post in April: http://www.busnut.com/bbs/messages/11/9854.html?1113855065 I'm using 8 compressors (I said don't ask...) but I'd remind you that if you use these, you will probably need to conjure up a full-vehicle climate system to prevent these from locking up under load or one A/C out of many cooling the entire vehicle when the door gets left open (I'm still working out the kinks in my system... Argh!) Tim | ||
| John that newguy Rating: N/A |
The 110v electric heater coil in the evaporative type cooling unit is very inefficient as compared to using a 110v compressor. The heating coil in the evaporative type uses more power than a compressor type and provides less cooling ability. The 12v electric heater heater was designed to keep the fridge at a modestly cool state -if- the door is not opened. It is designed only for travel and not to "cool" anything down, only to keep it as cool as it might have been before switching to 12v. The propane heater was designed to keep the fridge as cool as possible, but it is suggested that food desired to be kept frozen, be placed in the freezer after it is frozen. So with that.....I'd think it's safe to assume that the evaporative system used in refrigerators are not designed to cool more than a fairly small, very well insulated compartment. They simply will not suffice as an air conditioning alternative that would be at all practical in any sense. Very especially, in it's 12v mode. | ||
| Lin Rating: N/A |
Am I wrong in believing that propane friges are just using absorbtion cooling. That can be done with AC also, but I question if used frig innards are adequate. There must be some way to research there BTU capacity so you will know. Now if you can reclaim the wasted heat to make hot water, that would be something. Although, I must admit, that it is something I would not bother with. I have used the gen on the road, but consider it to be a poor way of doing it. An engine run compressor seems to make the most sense. | ||
| David Hartley (Drdave)
Rating: N/A |
Never Say Never about absorbtion air conditioning, Its been done. 60,000 btu @ 1 gal/hr. http://www.econoheat.com/chiller-specs.htm | ||
| James Maxwell (Jmaxwell)
Rating: N/A |
Guy: Absorbtion (Evaporative?) a/c is illegal if the unit contains more than 1# of ammonia. 1# will yield you a very small and mostly useless absorber for a/c purposes. There are other refrigerants available for larger absorber units that are extremely complex in operation and construction(Up to 10,000 ton that I have seen and worked on and that was some time ago). At one time, absorbtion units were available for light commercial and residential use, made by Arkla-Servelle. They were huge, complex, and expensive for their limited capacities. They required gas for generation, water for cooling, and special alloys for components, along with separate chiller coils. As the ammonia content exceeded the limit for direct a/c, they were water chiller units. They also required a great deal of maintenance and service; I loved them. | ||
| John that newguy Rating: N/A |
David- Uhmmm... But what Dave said, was: "I decided to spend some effort in determining the feasibility of using several (3-?) small evaporative units distributed throughout the bus. They would be powered with either 12V or 110 (for me, no propane) which should not overly tax the batteries, localized units means you don't have to move a high volume of cooled/return air for a long distance and fans will be smaller. quieter and take less power also. My source for units would be junk RV friges and repaired as needed. " And to that, the answer is no, it won't do; don't bother wasting your time and effort. Yeah, they make some real neat evaporative/absorbtion air conditioning systems for a real neat price.. But that wasn't the question. http://www.americasprideonline.com/waste-oil-heaters/Omni/omni-waste-oil-air-conditioner.s html Absorption cooling: http://www.ncsustainableenergy.org/efficiency/DukeSolarHVAC.html http://www.eere.energy.gov/consumerinfo/factsheets/ac2.html http://www.nh3tech.org/absorption.html I managed to learn on thing through the years - when one wishes to take the less travelled road, they better have a deep pocket to pay for the trip. | ||
| David Hartley (Drdave)
Rating: N/A |
I didn't say that, Guy said that! The feasability and technical issues are many and most probably expensive. Sanyo makes inverter/compressors for European air conditioners. But they are not without power or space problems. The simplest things sometimes are better. So having a dedicated high voltage input inverter running from 24/36/48 or higher volts and running a 220 volt A/C unit makes more sense. It would in effect be much cheaper to rig up a very small and fuel efficient diesel engine to an automotive a/c compressor and generator and run the A/C system directly with it. Those in the trucking industry are call "APU"'s, They are already available on eBay. The trick is hiding it and making it noiseless enough that the fans would be louder that the miserly little engine. Run it on SVO or Biodiesel or #2 furnace fuel from it's own tank. A long time ago stationary refrigeration compressors were mostly belt driven. Too bad there aren't too many left. Its also too bad that the Stirling Cycle engines aren't more commercially available. A nice little LP or liquid fuel burner to provide heat(hot water), Airconditioning and electric would be neat. Oh.. Wait someone IS developing that for RV use.... Just being silly.. | ||
| john wood Rating: N/A |
Mr Maxwell; Servel still makes 3 4 and 5 ton residential absorbtion ac units! Cool idea....... use waste exhaust heat to fire absorption ac for over the road use. $making ideea here? (for the otr bus companies) | ||
| John that newguy Rating: N/A |
OOps Dave!! Yeah... I meant "Guy said", not youse! Just another senior moment.. I digress........... alot... lately.. |