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Author Topic: Roof air or not?  (Read 2763 times)
wayne
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« on: August 03, 2009, 07:11:36 PM »

I went back and read the A\C posts for roof units vs basement air. It seems obvious that the basements units and split units(whatever they are) are superior but seem a lot more involved and require much more tech knowledge.  I had a 36' class A with 2 rooftops and never had a problem. Is the basement air as trouble free as the roof units and worth having considering the effort and extra $$ involved?
Roof air would be very easy to install, basement a/c would require me getting a lot of outside tech help.
I have a Setra 215 (40') without bus air, plenty of basement storage.

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« Reply #1 on: August 03, 2009, 07:51:14 PM »

If your bus is 12 volt you may not be able to run a rooftop AC from the inverter so mini splits would be better for going down the road because they use less power and may be able to run from a small inverter.

We can run the front roof top AC from our inverter so the front of the bus is comfortable until the heat really kicks in.

When you need lots of cool you have to run the genset to have both rooftops on.

Just my experience.

Melbo
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« Reply #2 on: August 03, 2009, 08:06:00 PM »

Choices, Choices,

Roof airs, take up roof space, basement airs take up basement space.


I have heard of people building a duct on the ceiling and using the roof airs to supply it, it helped keep quiet inside bus.

rooftop simpler

basement more aesthetically pleasing to some




What are your preferences? Cost, space, looks, power supply   I'm sure more help will come with more info.
 
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luvrbus
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« Reply #3 on: August 03, 2009, 08:07:30 PM »

You get more bang for the buck with roof airs and save bay space.
I am not a big fan of either I have 3 Curisair's with the split system in mine.
Nick will give you good advice on the units that is in his field of expertise.    

good luck
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MattC
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« Reply #4 on: August 03, 2009, 08:47:34 PM »

I found the smooth lines of the roof more pleasing that roof air warts.  Opinions are like,,,, well you know and they all stink. =)

I wanted to do nasement air (Coleman) but didn't want to deal with all the ducting as I'm short on time and aptitude. Now I hear they are hard go find.  I chose to install a pair of mini-split units as they only need freon lines run and a air handler mounted inside.  No pesky ducting, and according to what I've read quite efficient.

Here is a vendor that sells mini-split, there are a LOT of places selling these units but this was the first I found tonight.  I had a large list but can't find them now.  However, this will explain some of the Mini-Split hoopla! 

      http://www.qualitymatters.com/Ductless-Split-Air-Conditioners-s/188.htm

The db rating on some air handlers are:   Noise level dB(A) L-M-H: 35—38—42 
I'm thinking this is quite a bit more quite than the roof units I've see, however my experience is very limited.  =)
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« Reply #5 on: August 03, 2009, 09:02:47 PM »

From a personal point-I have three Coleman 13,500btu roof tops (non ducted) and they work great-albeit not as quiet as I'd like though.  In 105 degree weather, I can run two of them and maintain 75 degrees inside while driving (bus has 2.25" blown in foam insulation).  On this last trip, I came back to a 90 degree interior temp-turned on all three A/C's and in 30 minutes was back down to a comfortable 70 degrees.  Roof top airs are made for going down the road-although they add about 100lbs each to the roof.

Basement airs are also made for transportation-so they will hold up to the riggers of travel.  Most are just a roof top air reconfigured to basement use-mainly-they have the same components as the roof tops.

Mini-splits are NOT made for transportation.  While they may work well for awhile, they most likely will develop vibration problems as they age.  If you're willing to live with that, so be it.

I'm going to use Dometic 15,000btu basement airs (2) that are reverse cycle heating also.  In the bedroom will be a smaller 7,000btu, and in the cab of the truck also a basement 7,000btu.  The truck is 13' tall, so no room for roof tops.  Good Luck, TomC
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« Reply #6 on: August 03, 2009, 09:41:16 PM »

The Cursiair split systems are made for transportation or marine service I never had a problem with mine 
good luck
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« Reply #7 on: August 03, 2009, 11:39:00 PM »

When you hear Mini Split think conventional auto AC but the compressor is driven from an electric motor.  In most AC the motor and the expansion chamber where the cold is made are collocated.  The mini split has the compressor located in the bay and the "air handler" mounted on a wall in the living quarters.  You don't cut the roof but you do have to drill a couple 3/4 inch holes to get the freon lines from thee compressor in the bay to the wall mounted unit.  Nick has advised others that the Mini Splits for home use may not be rugged enuf for bus applications.  Others have come on line to report that their "house" units are doing fine after years.

The roof airs are the cheapest way to go...They are noisy.  If you duct them to defeat the noise you get  degraded performance but maybe the performance is good enuf for you?Huh

Basement takes up a lot of space.  Look at Nick's pics of his install.  His may be the best ever?Huh  I have heartburn with the amt of space his units take up for ductwork.  No ducts with the Mini.

Install two systems/units so you have a back up that might get you through.  With one large system you will NEED 220VAC to operate it.  With two 110VAC systems you can run one AC unit from a 30 amp pole and survive a really hot day.  That also applies to two roof airs but I think 1,500 BTU ratings are as high as they go and that only draws 12 amps with a large surge on compressor start-up.

Can you divine what is my choice???

Keep reading those old posts and asking the questions that you develop from them.  You will come to a much better understanding and make wiser decisions for your preferences.  I am not selling myself as any sort of expert.  I only hope to provoke better understanding on your part.

Pleasant journey,

John
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« Reply #8 on: August 04, 2009, 02:13:25 AM »

 I installed ducted rooftop airs in my coach cause they were fast and cheap. After years of full timeing  the noise really got annoying. I wished I had went another route.
 Then one day I was sitting there and the light bulb went on!!  I had ducted the cold air. I should also have ducted the intake air!!!! The compressor, fan motor all have a 14 inch hole to send the sound into the bus. For me it was too late.
 If doing again I would duct the roof AC the same as I would duct the air for a generator.   Jim
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« Reply #9 on: August 04, 2009, 06:36:25 AM »

For most folks, roof space is not going to be an issue, but cargo bay space is an issue.

I went with roof airs for cost and space reasons.  Not only cargo bay space, but also space inside for the ductwork.  I have a 43 foot bus, yet I have less lugage bay space than most 40 foot buses due to the short wheelbase.  My front luggage bay is only 2/3 the size of my other two luggage bays plus 1/3 of the rear luggage bay is (was) for the A/C condenser.  I have a generator in the condenser space now.
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« Reply #10 on: August 04, 2009, 06:47:02 AM »

We went with roof airs, because we will always need the space in the bays. Right now we are right at thirteen feet tall, with the due therm, low profiles. We don't have enough bay space, as it is right now.

God bless,

John
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« Reply #11 on: August 04, 2009, 06:47:26 AM »

I may be wrong but I believe service on a home type ac would be a major problem trying to find on the road installed in a bus.
We don't live in a perfect world when using our generator,inverter,and RV parks electrical outlets for running the Ac's just wondering how a house type mini split would handle that environment day after day.
And what is the big deal on the amp draw your making your own power or pluged in to a outlet at a park not like trying to run 2 or 3 AC's off the baterry bank and a inverter for 24 hrs a day 
Anyone got answers    

good luck
« Last Edit: August 04, 2009, 06:55:03 AM by luvrbus » Logged

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Jerry Liebler
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« Reply #12 on: August 04, 2009, 07:20:23 AM »

Some here would have you believe that roof warts and other rv AC are in some way superior to house hold minisplits and window units.  Such claims are either flat out wrong or very suspect.  All these AC units  are made of the same internal components and in fact the roof warts are often more skimpy in mechanical structure.  The big difference is efficiency and actual performance under high outdoor temperatures.  The rv industry has chosen to rate rv AC capacity and power use at 80 degree outdoor temperature.  The US government mandates that household AC be rated (capacity and power use) at 95 degree outside temperature.  Because of  the threat of government fines the household ratings are much more honest. The effect of this rating difference is that rv units, usually, use twice the power for equivalent cooling at 95 degrees.  Another effect is that a household unit that is rated at 2/3 the capacity of an RV unit will provide equivalent cooling when the outside temperature is 95 or higher.   Another big difference is in the noise level, roof warts are 60 - 70 Db while the minisplits are  40 - 50 DB and window units are 40 -60 DB.  A window unit can easily serve the bedroom by being mounted through the cap. a Ductless minisplit can cool the front even while driving in a 12 volt bus.  My verifiable, reproducable results:  18000 BTU/h minisplit draws 14 amps of 120v and cools front 1/2 of bus to 72 while driving on a sunny 95 degree day.
Also the minisplit heat pumps work as heaters down to outside temperatures near 0 while the roof wart heat pumps shut down when outside temps get into the 30s.
Regards
Jerry 4107 1120
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« Reply #13 on: August 04, 2009, 07:54:30 AM »

Wayne are you clear on the subject now   LOL . 
FWIW I found the Carrier roof mount AC is as good as is gets when it comes to blowing cold air and I have installed a lot of different units over the years. 
Like everything else here on the board  it is a personal choice like buying ice cream.     

good luck
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wayne
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« Reply #14 on: August 04, 2009, 09:27:25 AM »

I do love this board, You can get so much helpful information for whatever you are doing. Certain subjects always have so many different ways to go and this is definetley one of the subjects with more options. Everyone offers info and very persuading opinions that makes it hard to decide and of course cost is always a factor. I have really taken my time and attempted to do everything right because once I finish this conversion I want to enjoy it and not work on it. I am leaning toward the low profile roof units (warts) due to the ease of buying a new one wherever I am if necessary and bolting it on and I do like all my basement storage. I need to find out more about these splits, thinking about putting one up front for the driver.
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