| Author | Message | ||
| peter bartolo (Peterb)
Registered Member Username: Peterb Post Number: 5 Registered: 2-2007 Posted From: 66.178.166.61 Rating: N/A |
I checked around the board and archives but could not find anything...this is long and involved. I am a non-rooftop air conditioner guy ! there, I've said it...the last four busses I built used easy to get, window units (2) running on 115V (with a third spare unit aboard for immediate install if needed), after my go-round with two new (did I mention expensive ?) Coleman rooftops, that no one within 1,000 miles had warranty parts for, -and the units had to be shipped off for repair, only to fail again, and again, and a entire summer of no air.... never again. But now the Buffalo,,, heat-wise this system is pretty simple, and for going down the road should be fine, in port I have forced air propane and a marine wood stove. Air conditioning is another affair completely... the factory air setup is the reverse of what I need (it was designed to be an "on the road" system), I am only interested in "parked" useage. As with either two rooftops, or two window air units, I have dedicated two 15 amp 115 circuits for air (or, 30 amp 230), the split level decks present problems for utilizing window units. As I got into the existing air flow system , I determined that the system is so well designed (including the 24 volt blower motors) that perhaps a modification to the air conditioning side would be the easy way to go. I do not know the BTU or tonnage rating of the factory system, does anyone have this info? A modern two ton 24,000 BTU skid A/C unit (compressor, condenser-fan) fits nicely in the original condenser bay, and also uses R22, it is more than adequately sized, and pulls 25 AC amps at 230 Volts, but, there is not room for the "A" frame since a flat plate (automotive style) evaporator is used in the factory setup. Not being knowledgeable in A/C, I find the industry people to be overly secretive and unhelpful when asked about "designing" a hybrid system like this...and using the stock evaporator, or sugesting a replacement compatible with my compressor set-up... is anyone here on the board into A/C ? or can I get "referral" to a known expert ? any info/opinions/ideas would be appreciated. (Message edited by peterb on June 16, 2008) | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 360 Registered: 10-2004 Posted From: 71.230.13.96 Rating: N/A |
YOU NEED TO GO TO THE mak BOARD AND ASK nICK | ||
| Ed Roelle (Ed_roelle)
Registered Member Username: Ed_roelle Post Number: 58 Registered: 3-2005 Posted From: 98.209.249.151 Rating: N/A |
It is most efficient to move freon to the areas to be cooled, rather than air. The factory system is probably about 90,000 BTUs. I have seen a custom house system that utilized the production condenser with the lines separated to feed 3, 110 volt compressors below, and 3 evaporators in the living area. This appeared to be efficient, but complex and time consuming. Ed Roelle Flint, MI | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 467 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Pete, First off, Nick will reply here also. Secondly, as we are both air conditioning contractors, I think I know what he will say, because it will be my suggestions also. Busses have high capacity Over The Road (OTR) air conditioning for several reasons. The air is supplied up the outside walls and delivered at the windows, to overcome the heat of the sun shining in the windows, and to put it in evenly throughout the bus, instead of out of several registers. A register in the floor every two or three rows would make hot or cold spots. As you know, the side walls of busses are very thin, so there isn't much insulation, which means a lot of loss. OTR capacity in most busses will be 6-9 tons, because of the above. So, how do we central air a bus? The answer is a little out of the realm of the average residential installation company, due to some people wanting OTR coach heat, etc. and the condenser and evaporator (inside) fans being 12 or 24 VDC, or some condenser fans being belt, shaft, or hydraulic driven, and a hot water coil being in series with the evaporator coil in the air flow. I would consider two tons to be a little short on capacity, but it will take a new insulated duct system run under the floor, (along the top of the bays) with register(s) in each of the rooms to be able to get any results with less than about 5 tons. With a new well-insulated supply trunk line, properly insulated walls where the supply air used to come through, and less windows, a bus can be made to heat and cool well with much less capacity. Now all you have to do is get a 240 Volt evaporator fan, or a method of supplying 24 VDC through a convertor, etc. to your existing evap fan, a bunch of controls, and you're in! Sounds simple, but. The stock evap fan is too large for a 2 1/2 ton system, and the stock evap coil is also too large for the smaller air flow, and half of it would starve for freon if you went to use it. I also don't think a residential condensing unit would get enough air flow around it in a condenser bay, but there are ways around this. Now you see why a lot of A/C people won't talk about it. Sean Welsh has hand made a system for the front of his Neoplan, so he would be one person I would ask for comments. He will respond graciously! Someone else here has installed a 5 ton scroll compressor in place of the engine driven compressor in a newer MCI, using the entire existing duct system. He has converted both fans to 240 VAC, reports success, but says that "5 tons is just enough." As I said above, I feel the large capacity requirement is because of the large loss out through the sides, also I don't have his pressure readings, so I don't know if it was properly charged, which would greatly affect capacity. 25 Amps at 240 Volts is a LOT for a 2 Ton compressor, and I am suggesting what I am to leave something left for a 50 Amp shore power service. Jerry Liebler has had success with a ductless mini-split heat pump, he is well qualified also. This can be done, it just takes some out of the box thinking! Anyhoo, lets see what I have gotten me and Nick into this time, and if I haven't scared you off, my e is in the profile, don't be afraid to use it. Regards, George | ||
| Nick Badame Refrigeration Co. (Dnick85)
Registered Member Username: Dnick85 Post Number: 234 Registered: 2-2006 Posted From: 70.208.94.159  Rating: N/A |
George, I couldn't have said it better myself... Peter, Anything can be done but, at what cost? You are heading to the right path but, you are not quite there yet. I'm with George on this one. Trying to link up to a large system like your over the road coils may also cost you a great deal more in the refrigerant charge, operateing controls, and trial and error with endless adjustments. And still end up with an unefficient system.. I would suggest either basement units or a mini split giving you the biggest bang for the buck. Good Luck Nick- | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1210 Registered: 5-2001 Posted From: 65.74.72.93 Rating: N/A |
Peter, we followed the information from Jerry Liebler and bought three 18,000 BTU units like Jerry's. We've installed two in a building here in Ketchikan, and we've used one in a snowstorm, already. At the worst, the system defrosted four or five times in a day, so it wasn't producing heat for around 8-10 minutes each time. They only draw around 6.5 amps at 240 volts, and you can buy 120 volt smaller units. We think that they are good units and they weren't expensive. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 381 Registered: 10-2006 Posted From: 208.100.193.120 Rating: N/A |
We simply ripped everything coach heater radiator and evaporator out and tossed them. In the Evap bay we mounted a std dual RV basement unit. For heat a box heater was installed in the pax side in line with the vents in the coach. Delivery of air cond is simply straight up blowing into the cabin. Yes, its cooler in the fwd half of the coach than rear , but during the day , with the sun out , thats better. At night the aft double bunk is fine , and if we desire really cool a fantastic box fan moves enough air aft to hang meat. The hassle with the old bus air was constant leaks. A system that only used a couple of pounds a week was considered tight, Hound spent 1/2 the coach maint hours on the Air cond system , and Freon was 30c a pound. FF | ||
| peter bartolo (Peterb)
Registered Member Username: Peterb Post Number: 6 Registered: 2-2007 Posted From: 66.178.166.84 Rating: N/A |
Wow ! I was gone a few days and got back to this ! What great responses from all, and, exactly what I needed to upgrade my knowledge and see some different ideas. This board (and the entire BNO site) are simply the greatest wealth of knowledge and quality people we could ever have, ..thanx to all, VERY helpful. For those that know of me, I am marine oriented, and a 5 time "schoolie" experienced builder, but, a "coach" is an entirely different animal... the size difference alone is a huge dynamic, and having bay spaces available (like on the Buffalo), and the type of monocoque construction dismisses all of my earlier "schoolie" experience as similar to building only trawlers then buying a sail racer. Some points though (for others following aspects of this thread), I do almost everything myself, and always have repairability in mind when I design or build a system, cost is important, but not as important as being able to troubleshoot and get parts, do it yourself labor (saving the $75.00 /hr labor costs) plays in as well. I had "no" idea of how far I had missed guessing the BTU size of the original system, but, with the body heat of fifty or so people aboard, big windows, and poor insulation driving down a blacktop road in 90% humidity on a 100 degree clear day, anyone who ever traveled in a failed A/C bus in these conditions knows the agony. My Buffalo will not see the rigors of 30 below and 115 degree differentials like my schoolies all did, it will be primarily a Oregon winter coast and summer alpine service unit (a +20 to +100 degree F environ), but, the anti-condensation and insulation efforts will be the same as I have done on vessels and schoolies for years... I have spent time in some really fabulous tour busses of great expense, a simple "hands-on" ceiling and wall tour will tell you of the builders universal lack...the fact that they “can” oversize heat/cool/ventilation machinery (using your dollars) for these 2,250 (or so) cubic foot areas in disgusting disguise of poor insulation. After my rageful Coleman experience, I found it many thousands of dollars cheaper to "never" cut holes in your overhead, ram tree branches into your condenser, fight torsional rough road roof leaks, and a suffer through a mid day failure... by simply driving over to Wal Mart or Sears, or ? and buying another energy star stock unit for “immediate” change-out. I am retreating to my cave and some fresh thoughts on "how to air condition the Buffalo" for in port use. The inputs achieved here, having corrected my compass, thanx again to all who responded with quality information/opinion and data. peterb |