| Author | Message | ||
| Frank Mooney Rating: N/A |
Hello,my name is Frank Mooney,and for some time now,I've been reading all of your post,this is my first time posting.I have a 4501 that I'm doing some upgrades on,my biggest challenge is going to be supplying air conditioning to her.She came with 2 roof tops airs which I removed.I like the lines of the scenics,and don't really care for any type of roof wart so to speak.The bus at one time had central air,but the previous owner said that it didn't work that well,so he tore it out.I know of one gentleman (Frank Allen) that has a regular type of automotive set-up that runs off the engine,and I think I would like to run this type of set-up on my bus.The challenge is going to be,how can I run this type of system going down the road......boondocking....and in a campground using shore power.Any and all suggestions are appreciated,thanks.....Frank 4501-082 | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Frank, basement air is what you are talking about if you want the same system for driving down the road, at a campground or out boon docking somewhere in the middle of nowhere. This is based upon your desire to not have anything on the roof of your beautiful designed coach. You will need a reliable genset, preferably diesel, to supply power to the unit(s). I suggest you do a search of the archives for basement air or split air. I think you will find tons of information already available. Richard (Message edited by drivingmisslazy on June 05, 2006) (Message edited by drivingmisslazy on June 05, 2006) | ||
| Brian Brown (Blue_velvet)
Rating: N/A |
Frank, the automotive-style compressors would only be like a coach A/C system, and couldn't be utilized when parked (without an inordinate amount of "shade-tree" engineering). That's the reason most converters either use rooftops, basements, or mini-splits that work off of AC current... since those systems can be used while on the road or while parked. bb | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
If you are actually using a DC powered blower, a belt driven compressor can be used on an auxiliary powerplant. This will require a great deal of planning to make it run smooth though. If you are using a small engine to run an alternator to maintain your batteries and air pressure while stationary, it's not that hard to put an additional pulley slot for an A/C compressor. The trick comes in the way of maximising the ammount of work the aux powerplant is doing (i.e. taking the hot water generated in liquid cooled applications and heating domestic water and possibly the prime mover, charging house batteries, chassis bateries, air systems, etc...). You also have to ensure that combinations of these loads don't over-load the aux powerplant, and controlling the system may require some automation/interlocks/fail-safes. It's not impossible to do, but will require some thinking. Cheers! -Tim | ||
| Frank Mooney Rating: N/A |
If I should decide to go with an automotive set-up, would it be possible to run the compressor off of an elctric motor????how big of an electric motor would I need,and how big of an converter would I need.I don't have any room in the bays to speak of at this time,I do have a 8K onan diesel generator tho....Thanks | ||
| truthhunter@shaw.ca Rating: N/A |
Yes you could run a automotive air compressor (maybe 30,000 btu with an 5 hp electric motor compressor motor (22 amp/220 vac & start up surge) not including the condenser and evaporator fan motors, when on shore power and also run it off generated power when boon-docking or driving. Of course it would not be as efficient as turning the A/C compressor directly by belt drive off the onan generator engine and rigging it to also be run by the electric motor only when on shore power. You could also have two separate A/C compressors one in a central air style and a automotive compressor belt driven from your onan. Both could feed the same condesors & the evaporators that blow cold from the inside of the coach. The size of electric motor depends on the A/C compressor size and speed (and capacity) you intend to run it at. Is there always going to be 220 shore power to plug into if you go to a separate electric motor to drive a A/C compressor or a central air style? You will not get as efficient or compact and cheap and easy as the roof top units, which give up to 15,000 btu of cooling from convenient 15 amps at 117 vac, which is a best going to drive 1 1/2 hp electric motor, which will not run a very small automotive compressor very fast. As you want to save space , cost and also not have roof top carbuncles, the simplest solution is just go with a split system that is electric driven , much like central air in a house. These do come in compact sizes these days that will not take up a lot of bay space and are very efficient with a long life . Run it on the generator power when on the road or shore and plug in when on shore power. There are smaller units by LG that run on 117 vac and about the size of a big suitcase, very quite, and 15,000 btu each. Not sure if they come in heat pump configuration like the roof tops yet, shop around. The more complex the system the more wheels to reinvent and pay for. | ||
| John MC9 Rating: N/A |
There's a reason they put air conditioning vents high (like the ceiling), and heat vents low (like the floor)... I forget the science behind it... Frank, I fought like you. I did not want to put "carbuncles" on the roof, but the alternatives equated to mucho' $$$$$$. So my MC9 sports two 13.5 units up there, for all the world to see. The rooftop airs can be run from an inverter (using the bus's alternator), or the genset, or at the power-pole. I'm still working on the interior, but on the hottest day in Florida last year, I ran only one while working... and it was cool enough for me! It was over 90 outside, and I have not added any insulation to the bus. The Roof Top airs can be noisy. But, they're easy to maintain. And, they're easy and cheap to install or replace. The Basement airs are quiet(er). They are more expensive to buy (x2 or x3). They are more difficult to maintain and repair. They are more difficult to install. They require ductwork, and suffer efficiency losses of ducting. The "split" air conditioner units fit the same description as the basement type, but also may suffer the losses of leaks between the condenser and evaporator units, due to the amount of extra "plumbing" involved.. (also more refrigerant is needed for it to operate) There are "ventless" portable air conditioners (that do need venting), can be set in any room, or moved about. They are fairly inexpensive, and no "installation" is required. They sit on the floor, and are very portable. They look like a common dehumidifier. Running on 110v, they don't require 220 service. Their efficiency is debatable, and they should be vented, to eliminate the moisture problem. And of course, you can mount a common window AC unit on the floor, with the condenser venting out the side of your bus discretely, and the unit nicely hidden in a small cabinet... It will run on almost any amp provided at the poorest park, and keep you reasonably cool. All things considered? Man, do them carbuncles look good up there, OR WHAT? | ||
| FAST FRED Rating: N/A |
The Basement airs are quiet(er). >And dont blast air . They are more expensive to buy (x2 or x3). > usually because you get 2x the capacity (2 units in one box) They are more difficult to maintain and repair. > If installed properly they are easier to get at so frequently less work to repair. Although the Carbunkle route seems to lead to simple replacement , seldome repair. They are more difficult to install. > Unquestionably you MUST follow Da Book , and install returns, no returns no cold air. They require ductwork, and suffer efficiency losses of ducting. > Perhaps, the blower IS oversized at the factory to make up for lousey sticks & staples 5 min. instalations, but the extra power to the big blower is very minor. What is NICE is a cool coach with almost zero noise and no blasting air. Works for me, seperates the Coaches , from the Bus Campers. FAST FRED | ||
| Kyle Brandt (Kyle4501)
Rating: N/A |
RE: Man, do them carbuncles look good up there, OR WHAT? Carbuncles are undoubtedly the easiest & cheapest way to go, but..... For MY conversion. I'll take the OR WHAT. I don't want what everyone else has, that is one of the reasons why I bought a 4501 & wanted to do it my way. That is what is so great about this hobby! Cheers! kyle4501 | ||
| Rob King Rating: N/A |
Hi Frank Let me tell you my experience as I just finished a/c installation. I too didn't want the rooftop airs because of looks on my Prevost. I bought factory rebuilt Coleman super efficent basement air from here (James at Colaw RV Salvage 1-417-548-2125) for $800. These are 2 units of 15K in one housing. They require 20 amps each for surge and then 7-10 amps for continous service. There is a built-in time delay so the net effect is only 25 amps when the first is already running and the second starts. The duct work was constructed from a combination of galvanized metal and wall insulation board cut and taped into shape. The duct work was $125. Then I use 2" insulated flex duct to run to the outlet so all I have is a 16" X 4.5" X 25' main trunk with flex going to where I need the air. Cost $250 for flex ducts/diffusers. The issue with basements is time spent engineering the installation. As JohnMC9 says, you need cold air coming out at the ceiling and hot air returned from the ceiling. That and plenty of return air is the key to basements. I know it is possible to get that but it takes thought and time spent putting the engineering into existance. BTW, on this board and the other, Nick Badamine is an invaluable resource for a/c work. He does a/c for a living and has basements in his coach. Good Luck Rob 91 LeMirageXL Missouri | ||
| John Jewett (Jayjay)
Rating: N/A |
Hey F Fred. JohnMC9 talks like he has lots of experience with basement units. You and I do, and we both know he is way off base with all of his comments. Lot's of misinformed, misinformation there. I've lived with mine for almost 6 years, and after using roof top units too, I would not go back to them. I also installed one in an Eagle 05 and a GMC4106 (tight squeeze), and the new owners loved them. No water stains on the ceiling, no drips on the floor etc. BTDT ...JJ | ||
| John MC9 Rating: N/A |
JJ - "JohnMC9 .........Lot's of misinformed, misinformation there." I said: "The Basement airs are quiet(er). They are more expensive to buy (x2 or x3). They are more difficult to maintain and repair. They are more difficult to install. They require ductwork, and suffer efficiency losses of ducting. " And I offered "Lot's of misinformed, misinformation", where? (jeesh, man.... and you said you loved me, too....) | ||
| John MC9 Rating: N/A |
Frank - "(Frank Allen) that has a regular type of automotive set-up that runs off the engine,and I think I would like to run this type of set-up on my bus.The challenge is going to be,how can I run this type of system going down the road......boondocking....and in a campground using shore power.Any and all suggestions are appreciated,thanks....." The Welch auxiliary system is similar to an automotive system and is designed to cool the entire bus. I have one, and yes, it works great. It can't be used with an electric motor, I had been informed by Welch. Too bad!! But for "going down the road", it's nearly as good as the OE system. As others have stated, the basement units can be great. But they do take some engineering, and some power, to get to work great. In the order of price effectiveness and ease of installation? 1. Portable, "unvented" AC units. 2. Roof top AC units. 3. Home type window units installed in inconspicuous locations. 4. Mobile home "closet" AC units 5. Basement AC units and corresponding ductwork. Take yer pick! | ||
| FAST FRED Rating: N/A |
"As JohnMC9 says, you need cold air coming out at the ceiling and hot air returned from the ceiling. " Actually you ONLY need to remove the hot air that has risen to the overhead . There is NO reason to dump the cold air from above. Pouring in from floor vents works as well. After a short time the unit will "fill" to what ever level you can keep cool. FAST FRED | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Although I am not an A/C expert, I have always been told by those who supposedly know that it is better to dump the cold air in from the top. It was explained to me that this tempers the air and prevents the foot freezing rush of cold air on the floor. Richard | ||
| niles steckbauer (Niles500)
Rating: N/A |
Warm air rises and cold air falls - its stratification - some of the cooling that is felt by us is the movement of air - the ideal situation: Cooling - distribution vents high up and directed toward external walls, windows or any 'internal heat source' (this eliminates any 'hot spots' by circulating warm air away from heat sources and replacing it with cold air) - return should be either centraly located or scattered relative to distribution vent volume and should also be placed high up, but not in a location that inhibits the mixing of of the cold supply air (a good place is above the distribution vents) Heating - basically the inverse is true with the distribution low and returns below them - vents directed at heat loss areas Make sure that the supply volume and return volumes are identical so as not to suck moist air in or out and into your living area, wall cavities, ceiling cavities and bays - FWIW | ||
| Frank Mooney Rating: N/A |
Well one thing for sure,I got a lot of responces to this post,and the answers are their,I now have to decide which one,I wish to thank all of you for your inputs.............Frank 4501-082 | ||
| George
Rating: N/A |
Dear Niles, Stratification is when air stays still in levels of the same temperature. Convection is the rising of hot air, or the falling of cold air. Sorry. The important things are enough circulation, and enough refrigeration capacity. I also disagree with "truth hunter's" statement of the ability to run two compressors on a "parallel" configuration. This would cause a failure of one compressor due to oil return building up in the un-used compressor. This discussion has taken on some of the complexion of the discussion of radiator cooling methods, efficiency doesn't matter, what you are trying to do is cool the engine! (Not to mention that what we're talking about is 5 or 10% of 25 HP?) My MC 6 has the original 37 year old hydraulic driven fan which is temperature controlled, and doesn't run at all below 180 degrees, and works well! I'm not going to get into the small efficiency loss of driving the pump with the bypass open, (below temp) or friction loss of fluid flow thru hoses etc. Back to the issue at hand, the best practical way to cool a bus is with electric air and a generator, then cooling is available at all times, period. We have to remember Frank's OTR air is gone. Electric air CAN also be run OTR with a fairly large 24V inverter! Another suggestion, (as I own an air conditioning and commercial refrigeration company) is installing one central compressor, about 2 1/2 tons, with its own condenser and evaporator in series with the air flows in the bus system. This will require a 24V inverter with about 75 amps of battery charging capability to run the bus heat and air blower when on 50 Amp shore power or gen. Or, convert the bus heater A/C blower to 120vac, and run it OTR with the inverter... Permission granted to edit out the previous paragraph if you don't want to start a firestorm! Thanks, George | ||
| niles steckbauer (Niles500)
Rating: N/A |
George - no reason to apologize - I may have been brief and incomplete in my post, but I was merely responding to the immediate prior posts (not the thhread) and indicating that no matter where the air comes from it stratifies and forms layers of temperature zones - It wasn't meant to be an explanation of thermodynamics - sorry if I was unclear in my prior post - Niles strat·i·fi·ca·tion ( P ) Pronunciation Key (strt-f-kshn) n. Formation or deposition of layers, as of rock or sediments. The condition of being stratified. A layered configuration. Source: The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. strat·i·fi·ca·tion (strt-f-kshn) n. An arrangement in layers or strata. (Message edited by niles500 on June 17, 2006) | ||
| John MC9 Rating: N/A |
(heh heh heh. Aren't these threads fun?) Actually, the air is moving, not static, so "strat·i·fi·ca·tion", (which pertains to a non-moving mass), wouldn't necessarily apply to a movement of air..... Convection, would be the more applicable term, wouldn't it? | ||
| JW Smythe (Jwsmythe)
Rating: N/A |
Just to add... John is right, putting the cool air in from the top sets up a convection current. It is also ideal for pulling in the warmer air to cool. Having both the inlet and exhaust for an air conditioner at the floor level will give you nice chilled air at floor level, but it won't force a convection current. If your cool air supply is in the floor, you can help it along with fans, but it will be far from ideal. Nothing is forcing the hot air off the ceiling, and you're trying to push hot air out of it's place. It will tend to rise again. Fans establishing a flow are better than fans in random directions. For example, if you have basement air in the rear of the bus, point fans at floor level towards the front of the bus, and fans at roof level away from the front of the bus. That is assuming an open area. It will need to be adjusted for obsticles, such as walls. Having your intakes high, you're pulling in the hot air, then cooling it so it can fall. The opposite is true for heat. You want to reverse your ducts, if possible. I've never seen anyone reverse the ducts. Homes are usually designed for the typical environment, and efficiency is lost in their off season. This is why you see homes in the north with their heater registers on the floor, or near floor level. Homes in the south usually have air conditioning ducts in the ceiling, or near ceiling level. There are notable exceptions to this. Mobile homes usually only have registers in the floor. This isn't for cooling efficiency, it's due to poor design. An air conditioner performing well will be right around 40 degrees at the outlet. That air will drop fast, but it will also disperse with the warmer surrounding air, so unless your insulation is excellent, you'll never achieve 40 degrees. Since building a bus like a refrigerator would be very ugly, don't plan on achieving 40 degrees. You have to match your cooling ability to your heat load. Heat load includes people, electronics (computer, TV, stereo, etc), stove, engine heat, and loss points like windows and doors. There are calculators for figuring out exactly how much air conditioning is required for a home. I haven't seen any for buses or RV's. If you know the R value of all your insulation, you can use an online calculator for homes, but reports from other people here are very useful. I seem to remember someone saying 2 15k BTU air conditioners was more than sufficient on a 40' bus. Giving too much cooling capacity will cause short cycles of the air conditioners, where you'll get a blast of cold air, and make it uncomfortable for the occupants. Too little cooling capacity, the air conditioners will run constantly, and frequently not meet the demands of the occupants. Luckly, with multiple units, you can choose to not run one or more. Installing 3 units, you can choose to leave one off all the time, and then you have a redundant unit, should one fail. I knew a year in HVAC school would do me some good eventually.  | ||
| FAST FRED Rating: N/A |
" Nothing is forcing the hot air off the ceiling" Those that follow the instalation insructions of the basement mfg will have the RETURN DUCT , sucking the hot air off the cieling. The cold just fills the coach like water in a bucket. FAST FRED | ||
| truthhunter@shaw.ca Rating: N/A |
Why not just reverse the ducts between heating & cooling modes with a bit of extra duct work "valve". I have often wondered why this is not done with central heat/air condition. If reversing the duct cases dirt to blow then the duct either needed cleaning or filters added at the register to prevent the dirt from getting in the ducts first place. (the laws of thermal dynamics = cold falls & warm rises; under the influence of gravity at least) |