| Author |
Message |
jvicars4 (24.28.16.148)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 6:13 am: | |
If you insulate the roof properly can you properly cool a 40 coach with 2 roof airs? I would like to minimize the number of units. Would the proper insulation allow for this method?
Jamie |
Geoff (Geoff) (66.238.120.121)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 6:18 am: | |
A lot of people run only two roof airs in 40'er. I put a third one to fill the void in the middle of the bus since my other two are at the far ends. I don't necessarily have to run all three at the same time, but having three gives me more options in how I am going to cool the bus.
Geoff
'82 RTS CA |
Pete (205.188.209.11)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 6:49 am: | |
I have run into a problem with my present genset even running 2 air units. its either 1 unit or the generator shuts off after about 20 mins. I knew i needed a larger genset and am headed to a Onan Marquis 7000 which should take care of everything plus but id only go with 2 units, I"ve never seen 3 roof units in a rig but what i have seen was some clown hooked up a used HVAC unit from his house, it took up the whole bay and could generate enough cold air to stop global warming Im thinning that it was a bit of an overkill.. |
Richard Bowyer (Drivingmisslazy) (66.190.119.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 8:14 am: | |
I have a 40 ft well insulated Eagle, and believe me, two roof airs are not enough when travelling in the southwest, especially during the summer months. If I had my druthers, I would have three roof units plus a drivers air blowing cool air up on the windshield to try and cut down some of the heat thru the windshield. I sugggest you do not listen to anybodys advice about A/C till they have BDDT.
Richard |
Frank Allen (152.163.205.72)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 9:47 am: | |
I have a 35 ft with two airs on the roof and it does pretty good, but i also added a small set up run from the engine that is piped out the dash and a second one in the rear and thats all i really need when it is 100 out and i have 4 people, i can still start the gen set and start up the roof airs , i like this set up very much , the answer to your question is probly not, but there are many varables when working with this kind of thing .
Frank Allen
4106 |
Don KS/TX (205.187.92.123)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 9:54 am: | |
All Roof Airs Are Not Created Equal> I thought that the two 15,000 btu units on my insulated 4905 were more than adequate, but most roof airs are the 13,500 size. I only ran two to cool off when it had been sitting in the sun, after a few minutes one was plenty. A full time friend has the same results. A lot of people use the third for the same purpose, AND there is a great redundancy factor there too. |
Don Peter (198.81.18.174)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 11:07 am: | |
We have only one 15,000 btu roof air on our 4104. We travel regularly in the southwest and find it adaquate. Our roof air is toward the front of the bus which is our living area. With the genset running it keeps the driver comfortable while running down the road. Usually if it is still hot in the evening we open the rear fantastic vent with the fan on exhause while the air is running. About 1/2 hour of that makes the rear bedroom cool enough for sleeping. There have been a couple of times in Laughlin, NV when that wasn't sufficient so we just folded out the couch and slept up front under the roof air. -- Don |
Scott Whitney (66.82.9.32)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 11:40 am: | |
I would also recommend to properly insulate around the engine area. After a long drive in hot weather, no sense asking your rooftop units to remove the heat that a 1500Lb. block of hot steel is radiating too.
I've got about 3" of block foam and plywood btwn the engine and the bedroom and I cannot feel any stray heat radiating thru from the engine.
Scott |
Joe Laird (Joelaird) (198.81.20.172)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 12:15 pm: | |
We've got 2 roof airs and have traveled at 108 degrees. I know, I learned not to be in those temps if I can help it..
Ours cools fine. You can hang meat with both airs on. We find the front is plenty when traveling. So we just run it off the inverter. We need the generator to run both plus the fridge.
Our Eagle is well insulated and has thermopane windows. I believe the thermopanes is money well spent. I also find with the day/night blinds down it is very easy to heat/cool. Could be the mid day sun doesn't hit the windshield so much because of the visor also. Awnings help considerably.
Our bus is dark blue but the top is white. Many of our friends in the southwest have white buses.
We have a lead sheet on the bedroom floor and the temp of the floor is the same as the rest of the bus. Never had any engine heat coming through. I think if you have engine heat radiating you ESPECIALLY should have a carbon monoxide detector.
brrrrr, Joe |
Larry Baird (Airhog) (66.171.53.10)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 12:41 pm: | |
You had to know I would respond to this. 2 or 3? Add them together and you get 5 and that what I have. Think of all the combinations I have, and if the refrigerator quits, no problem just put the stuff on the table. I can run 4 at a time and number 5 with a little shore power. Larry Baird (Airhog) (66.171.52.125) |
Geoff (Geoff) (66.238.120.8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 1:13 pm: | |
I see these border patrol buses here in California and it looks like they might even have more than 5 roof airs on them. I wonder what the story is behind that?
--Geoff
'82 RTS CA |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 2:35 pm: | |
Probably two are actually air conditioners and the rest are spy antennas.... |
Johnny (67.241.166.66)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 8:13 pm: | |
I'm planning two 15K units for my 40' skoolie (~32' living area), plus a dash A/C unit. 2 things: color makes a BIG difference--there's a reason most RV's are light-colored (and why my bus will be silver-gray with a white roof). Also, a suggestion I'm amazed nobody has mentioned: tint the windows. That cuts down on heat considerably, and also gives some privacy.
Definitely insulate the engine area--my long-nose got a coat of spray-on undercoating on the firewall, and the difference in heat (and noise) is considerable, even in the cold weather. Also, anyone with a trans--especially a slushpump--running right under the floorboards (Crown guys, this means you!), take a long drive, then feel the floorboards. The amount of heat coming through will floor you (pun intended). On my friend's Dodge Coachman class C, the floor would actually get hot to the touch (it MELTED the carpet glue!) before we insulated it.
Pete: you know, that guy just might've been onto something. |
Don KS/TX (205.187.92.79)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 9:20 pm: | |
Some great points there, shades, tinted windows, insulation, color of paint all play a part in the original question. One that was NOT mentioned was roof coatings. I used the ceramic bead paint, and swear by it. On a hot sunny day the difference is dramatic. |
jc (205.188.209.11)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 1:22 am: | |
Two is nice, three is better. Driving into the sun on a hot day will convince you to put one over the driver section. Working over the stove will convince your better half to add one in the middle. Cooling down the rear after a long hot run is quicker with one in the rear. Long term cooling on warm days can be accomplished with the middle or rear air, thus keeping the noise down in the living area. I recently added the Dometic remote controllers, and now wish I had done it years ago. The controller actually turns the entire unit off once the desired temperature is reached, and will vary the fan speeds based on temperature differential. The same unit will also control you heating and ventilation systems. (40 footer with Peninsula double pane windows, silver roof and dark exterior colors) jc |
john marbury (Jmarbury) (65.100.118.13)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 8:20 am: | |
Don,
did you use the ceramic bead paint on the inside or outside of the roof?
Has anyone uases Rhino Covering on their roof?
If so, how is it holding up. Local paint shop says it will dull and yellow in 1 to 2 years.
Any coments?
John |
Don KS/TX (205.187.92.129)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 9:14 pm: | |
Only used it on the outside. It yellowed slightly in several years, but in violation of the rules, I did NOT put the sealer on it. Would be really easy to just put on another coat to whiten it up again. On other ones I put the sealer on, no problems with discoloration yet. If you got back issues of Bus Conversion Mag, it is Miss Apr 2002, looks pretty yet. |
Buswarrior (Buswarrior) (64.229.213.34)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 13, 2003 - 5:58 pm: | |
FWIW
A couple of summers ago:
1975 MC8, full set of stock OEM dual pane coach windows, stock insulation, wide open inside, interior stock skins in place, no seats, no walls or rooms, only a roughed in table, sleeping on the floor, using the cooler with bags of ice and cooking on the coleman stove outside....
So, no improvements to MCI's, at the time 25 year old, exterior weather protection shell and attempts at maintaining creature comfort.
2 roof airs, Dometic circa 1986 models, plugged into the 30 amp shore power and running all day on high with the thermostats set to their usual comfortable settings.
Sitting in one of those "campground in the fields" in the sunshine all day. ambient temp 95 degrees F
Closed up tight while family off enjoying the local area and campground swimming pool.
Inside, 70 degrees F, and occasionally one or the other compressor would cycle off.
So, there was still some cooling capacity left.
Yes, you could feel the heat radiating from where the roof ribs are, the windows, etc.
No, opening and closing the door a bunch of times when we returned did not destroy the sanctary of cool.
Considerations:
1) What is the payoff for fooling with the stock insulation? Do what you want, but don't think that you HAVE TO change your insulation.
2) Consider stopping excessive air intrusion to your coach first. Insulation won't help if the wind is blowing through your window seals, up through all the driver controls, around the door, engine access covers, roof hatches, roof airconditioners, etc. Chase your drafts first, then see how it works.
3) It does take lots more cooling to pull down a hot coach. If your intended use will put you in the postion of having to return to the coach out in the sun and having to deal with the way over 100 degrees sun soaked interior, more roof airs will do it "quicker". This is the same discussion as bigger motors. Just how much faster is it, and at what cost?
4) You can easily add another roof air later, if you plan for that eventuality when you are building. Identify the place, rough in the wiring and forget about it, until you try out your coach with fewer AC units. If you are happy with one or two, it only cost a few feet of wire. If you decide you want more cooling, get out the saw, and there you go!
5) Adding another roof air will cost the roughly US$600 that everyone charges for these things, and an afternoon of labour that won't tear the entire interior out of the coach.
Compare that to doing something with the insulation.
6) How do we get that third AC unit to run at the 30 amp parks without tripping the breaker.......or with a 5000 watt genset.....? Oops, a whole 'nuther set of challenges!
7) Really helps to do some pre-running with your coach. Functional items installed, pretty interior waiting to be installed. Lots easier to make adjustments to functional things if the pretty interior is out of the way.
Everyone decides how to spend their money and time. As long as you are happy, that makes it right.
Down the road, you'll be so proud of yourself for planning ahead, no matter which path you take!
happy coaching!
buswarrior |
Buswarrior (Buswarrior) (64.229.213.34)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 13, 2003 - 7:41 pm: | |
Sorry, I should have included that the coach heat and air are still fully functional (converted to R134a) and are used while underway, which is an important variable in the decision making about AC configration.
happy coaching!
buswarrior |
David Anderson (66.90.196.156)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 17, 2003 - 11:02 pm: | |
I saw a Prevost today in San Antonio TX that had 6 rooftop units. Yes, I said six!! I had to turn around and look twice. Wow, lots of generator power and I guess you could hang meat inside. |
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