Roof Airs

[Ledo]

Hello folks! Lee and I are the new people on the block and have a problem with Prevosts. Problem is I drove one. Toast now. Must have one. Besides that I have joined POG forum.
I am considering a 99 Marathon which only has 3 15K BTU ac units on the roof. I have a friend who owns a Liberty and hammers me daily that I better get one with bus air or you will regret it. Question is, how well do the 3 units handle the heat during the hight of August weather in the South? Down the road? Sitting? Is 4 better? 5? Cruise Airs? We will not be hot!
Thanks for the input! Great Site!

Doug and Lee
New Port Richey, Fl

[Mark3101]

You will get multiple answers on this. The Liberty gang will say that getting OTR air is the only way to go, and about the only way you will find it is on a Liberty. I have a 4 roof air setup and have not had any trouble so far, but have not spent a great deal of time in very high heat areas yet. I have been in 100+ degree heat and have not had trouble cooling the coach to my satisfaction. One thing you have to be sure on is how many roof airs you can run from your inverters while going down the road without running the generator. I can run 2 (any 2) off the inverters or all four on genset or shore power. I have found that running 2 with the dashboard air going down the road seems to be ok most of the time. I have fired up the genset and run all 4 a couple of times and it did get cooler, so that is always an option.

I do not have any direct experience with Cruise airs on a coach so I can not comment on those...they have different issues that other can address.

I would find the coach you like and not worry so much about one thing. You may pass up what could be the perfect coach for you if you hold out for OTR air and it is the only thing missing...just my opinion for what that is worth.

[garyde]

If you spend a lot of time in the South, South West or the East Coast in the summer months OTR will keep you very cool. Temp in the Coach will remain in the 70's while its over 100 outside.
I actually have to turn the temp up at times because its too cold. My kids sometimes throw a blanket on while watching tv in the bedroom.
OTR uses up bay #3 on both sides of the coach so you'll have to decide if you need the added storage.
The OTR blows cool air up onto the windows so it keeps the heat off the windows and circulates thru out the coach.

[Seabyrd]

We live in TX and it's very hot here.. We had a 45' Navigator with 3 roof airs and nearly died from the heat. I personally do not believe that 3 roof airs can cool a 45 footer consistantly in the South .. I understand that we're not comparing apples to apples.. but you should listen to your friend... go with 4 or bus air. We upgraded to a 45' H3-45 with bus air and it will freeze you out on the hottest day. We love it !!
Welcome to POG !!

[Alek&Lucia]

Hello Doug and Lee,

We had two Prevosts with out OTR, and now our present "H" with OTR is the winner !

Alek

[Ledo]

Thanks for the replies. No doubt OTR air is the ticket. So taking the OTR out of the picture, will the three 15K roof airs handle 45' going down the road? We all know these things dont cool as well while in motion as they do while stationary.

[Jon Wehrenberg]

Short answer....no.

The bus absorbs a lot of heat, and Marathon which has a lot of glass, black glass at that, on the sides, acts like a rolling solar panel.

The best you are going to get per AC unit is 15,000 BTU (13,000 BTU most common) for a total of 45,000 BTU. At the very least get a coach with 4 AC units. If you can, get OTR which has a capacity in excess of 80,000 BTU.

Here are some things to consider. If the coach does not have OTR consider you are going to have to run the generator so the entire coach stays cool. Running one or two off an inverter seems to be what a lot of folks consider, but at the end of the day you may have a heat soaked bedroom because the two units operated while driving tend to be the front ones.

With marginal AC capacity available you can never let the coach get warm because trying to cool down a heat soaked coach with only three AC units is a challenge. It is a challenge for four units.

Your comfort level may be such that 3 AC units will be OK. I am comfortable when the temps are 70. At 75 in the coach I am starting to get warm. At 80 I am suffering. But I have an aunt and uncle that live in south Florida and they won't turn their house AC on until it gets to 85 so different people have different interpretations of what is acceptable.

You are correct about differences in performance when in motion and stationary. It can be compared (in heat terms) to the difference between a conventional oven and a convection oven where the flow of air makes a huge difference in how fast something heats up.

When considering what works for you, keep in mind a few things. No matter how the coach is cooled while in motion you are going to use similar amounts of energy. Whether using an inverter, a generator, or OTR the watts of energy required translate directly into horsepower to drive an alternator, a big compressor, or the running of the generator so if someone trying to sell you one coach over another suggests somehow the way the coach they are selling is more efficient be suspicious. I am talking apples and apples here. Once a coach is at a comfortable temperature for you, no matter what system you have for cooling the BTU loss is going to be the same and the energy to compensate only varies slightly.

I won't own a coach without OTR because I like the ease of use and its unmatched ability to maintain any temperature I want regardless of outside temps, hot or cold. The space it takes up is the equivalent of 1/2 bay. That space behind the AC condenser and evaporator is used for the fuel tanks so even without OTR you don't gain significant space and usually those coaches without OTR eat up whatever space is saved with more batteries to handle the load of trying to run AC units off inverters so again its a toss up.

One last comment about 3 versus 4 AC units. Presuming 3 AC units handle the temps satisfactorily, when one quits you may not be comfortable. The units for the most part are reliable, but the only time they fail is when we are on the road using them. They don't quit at home in our garages where we can deal with the failure without discomfort. Having 4 AC units allows that failure to happen (if it happens) and you can at least complete a trip without a visit for repairs or suffering in heat. I think 3 units in a 40 footer without slides will be OK, but not a 45 footer.

[truk4u]

Doug,

Here's my take on OTR after owning 3 Prevosts with no OTR...

94 Liberty 40 - 3 Cruiseairs - Stationary they worked great, in extreme road heating on generator, they shut down and all you have is dash air.

97 Marathon 40 - 3 Cruiseairs - Stationary they worked great, 2 ran off inverters while driving, but again, extreme road heat they shut down and dash air only.

00 Country Coach 45 - 3 Roof Airs - Stationary and on the generator they worked great , CC's version of bus air did the job and generator usage was not necessary.

Keep in mind that my usage is mainly east of the Rockies mostly in the southeast and if I was doing the desert thing, OTR would be the only option. So the bottom line for me would be roof airs or OTR. I really liked the Cruseairs, but 90+ degree's in GA during the summer afternoon will have you looking for a cold one!

[hobobimmer]

Howdy Doug and Lee:

Deb, Jay, and I had a 92 Angola with over the road air, plus 3 roof airs. In Nevada, I think late summer 2008, our over the road air breaker tripped and we didn't know how to reset (we were still kind of new to this bus thing). So we ran generator and the three roof airs as we crossed some Nevada desert. Outside temps around 100. Three roof airs running lowest temp setting on thermostat wouldn't cool below 85. It was toasty. That was extreme situation, I think.

That experience gave us a very direct comparison of over the road air (very effective until the breaker tripped) versus three roof airs (totally ineffective) in the heat of the Nevada desert in the summer. This is not a sales pitch for getting over the road air. You will enjoy whatever you buy. Happy bus searching.

Eric Faires
Huntsville, TN

[Mark3101]

Since I don't know, I have one question...what is the normal setup for buses with OTR air for when you are stationary? Roof airs or bay mounted Cruise Airs?? Have you ever had a failure of the OTR air when on the road and how has the "other" setup work for you when actually driving?