New member from Florida with questions

FYI I learned this week that roof air comes in two different BTUs 13500 or 15000.

I learned this as a result of being on the warm side at the beach last week with temps near 100 degrees and no shade. I had 2 of my , 13500 roof airs replaced yesterday with two 15000 BTU by Russell Coach in Knoxville. I called Rob from the beach and asked if he worked on them and he said no he just replaces them, when they start to fail it is time to replace.

So that is what we did and of course I am not at the beach but it was 92 degrees here yesterday and I had the temp in the coach at a cool 69 degrees.

Rob @ Russell Coach is a pleasure to do business with.

Anyone trying to decide on the AC systems for a coach purchase needs to recognize that what might be comfortable for some may not be for others and that is likely why there are choices.

Both my wife and I are very uncomfotable in heat. Heat to me is defined as anything over 72 degrees. And I want cold air blowing on me while I drive. I have an aunt and uncle that will wear a coat if the temperature drops into the seventies and they set the AC in their house at 85. If they were part of this discussion you would think one roof air would be all that was needed.

So everyone here is providing their evaluation of the AC systems based on their perspective and they are all correct.

There is one recurring theme here that needs to be understood. From reading the posts it could be thought that having ample AC capacity means everyone in the coach is going to be wearing blankets or coats. The reality is that no matter how much cooling capacity a coach has, and in whatever form it takes all systems are controllable and once the desired temperature set point has been reached the AC units cycle on and off to maintain temperature. What has not been stated here and needs to be recognized is each system is likely ducted differently so in addition to being able to maintain a given temperature the AC system needs to be able to disperse its cooled air in such a manner as to not have hot or cold spots.

I have no clue whatsoever about how roof airs or installations other than my Liberty work, but I do know my OTR is superior to the Cruise Airs in cooling without having hot or cold spots in the coach. For example, my front Cruise Air moves a lot of air around the living room (salon for rich folks), but there is one spot on the passenger side sofa where the cold air blows directly on you. The other Cruise Airs and other places in the coach are OK, so give some thought to the cooling systems with respect to distribution but do not worry about having excess capacity. It is like horsepower. You only pay for what you use.

Thanks Ray, I just was confused about the different systems and how they were installed in the bus.

I also think that there are other considerations in regard to HVAC units,all units that are low in the coach(in the bays) will help the coach drive better because the center of gravity of the coach has been reduced.Donnie said that cruise airs can draw 14-17 amps,I have never seen over 14 with any of my 4,I do agree that the differential of cruise airs is usually 15-18 degrees,I do have one that is close to 20,but I also have one that is 13.Donnie also said that roof airs will have 20-22 degrees of differential,I agree but I cannot get a roof air to live past 5 years and cruise airs are usually still going at 15 years old.

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Originally Posted by jack14r

I also think that there are other considerations in regard to HVAC units,all units that are low in the coach(in the bays) will help the coach drive better because the center of gravity of the coach has been reduced.Donnie said that cruise airs can draw 14-17 amps,I have never seen over 14 with any of my 4,I do agree that the differential of cruise airs is usually 15-18 degrees,I do have one that is close to 20,but I also have one that is 13.Donnie also said that roof airs will have 20-22 degrees of differential,I agree but I cannot get a roof air to live past 5 years and cruise airs are usually still going at 15 years old.

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Im sorry to disagree, but I have been working on Cruise Airs for 24 plus years. In a boat they are the best, in an air cooled environment, they are the least efficient of all RV a/c units. If you would like to look at my HVAC report (a report I use to separate different unit types) I can show the ratio of Cruie Air repairs vs roof air. The older Cruise Airs, 90's were worse on efficiency, but the newer units 2005 and up ( with the new style Hot Gas Bypass valve) are the most problematic. What meter are you using to test "fla"? The best efficiency from a Cruise Air unit can only be achieved by blowing the supply air directly from the evaporator into the living area, any ducting drops the Cruise Air efficiecy. Now let's look at the cost.... How much does 1 roof air cost? How much does an inefficient Cruise Air cost? I rest my case! You can buy 4 roof airs for the price of 1 Cruise Air (retail of course)

One more thing, call AAP Monday and see how long it takes to get a new evaporator or condensing unit...BTW.. I could be wrong on the exact year of the hot gas bypass change, but the old style can be identified by looking at the body. It has what appears to be a "stud" with a nut on the end while the new (pos) style has a plastic cap covering the body. The best thing to do if you have the new style is cut the worthless valve (it allows you to operate in heat pump mode, which is a total waste anyway, a couple of degrees colder outside) out and solder the lines so as to "by pass" " the bypass"!!

Cruise Airs are quietier than the roof units. But because they draw air from the underside rather than the roof they will not work well with hot ground surfaces. But they are not th primary source for A/C when traveling.

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Originally Posted by garyde

Cruise Airs are quietier than the roof units. But because they draw air from the underside rather than the roof they will not work well with hot ground surfaces. But they are not th primary source for A/C when traveling.

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That is true with the traditional method of installing roof airs. There are some very unique ways of installing the units and routing the return air, which yield a "quieter than a Cruise Air" result. Again, remember, ALMOST every RV service center in the US has access to a replacement roof unit! The same cannot be said about the others....

Oh and FYI, there are hundreds of Vantare coaches on the street that run 2 Cruise Airs (some run 4 off the inverter with the new 500a Niehoff alt...) while traveling at highway speeds with out the unit shutting down.

Donnie,I hope that you agree that roof airs increase the center of gravity and that as a result of increased weight on the roof the coaches drive worse.I am using the Liberty panel,but I could use a Fluke amp probe if it will make you feel better.