Air Conditioning/Inside the Pipes

We just spent a great 3 days at The Great Outdoors With our newest best friend Bill and while there realized another element of the OTR A/C that has, with other conciderations, made me decide to change my mind about that option.

The straw that has broke the camels back was when we realized for the first time, when getting a nickle tour of Jody and Bills bus, the normal baseboard at the bottom of the walls in a bus without it. We had no idea that if no OTR A/C, there will be no 1FT high by 5inch duct that runs all the way around the base of the interior walls of the bus. In this game when square inches ,where you can get them, are so important, and that, combined with all the other space issues that surround this option, in my opinion, make it too much of a compramise to make.

If I knew 9 months ago what I know now this is what I would have done. We would have gone with a large automotive style A/C compresser,for a drivers air only off the engine. We would have then either replaced our inverter with another large enough to power a cruise A/C or added a second indipendent inverter specifficly for that purpose. Either inverter setup i've proposed would have been capable of powering either the rear unit or the one mid ship building in some redundency. If and when the ambiant temps are such that 1 rear cruise air combined with drivers A/C off the engine would be insufficiant the gen. would then come on to run a third unit.

That would have given us the same comfort while at the same time doing it more efficiently, and giving us that all important MORE SPACE in the engine compartment, a whole nother empty basement bay and all that additional interior space that we have just learned about around the base of the walls.

Also if no OTR A/C the heat would come out at the floor where it was needed instead of at the bottom of the windows where you have to get the bus interior temp. 90 to warm the floor area acceptibly.

This proposed alternative solution might even cool the cockpit like we expected the OTR A/C to do but dosen't.

Well there it is for those of you still looking for a bus. My 2 cents. You can take it or leave it. This option will not be real high on the priority list if we ever replace our 86.

Very well put, Joe.

And as I began suspecting after I proposed the question to everyone, OTR A/C or Not..?

Most everyone agreed that OTR A/C was not worth the additional money, loss of bay space, HP loss, and therefore NOT something to look for in a coach, but something to consider only if everything else in that coach is what you are looking for.....!

Given the money I have spent on getting my Country Coach A/C working, which IS a glorified auto AC (but bigger) working, I would have chosen Prevost OTR in a heartbeat.

OTR in new coaches doesn't necessarily come up around the baseboard as you mention, but I believe at one point (mid 90's) it came up through the window panels, and many of the new buses, the OTR is piped in with the general A/C system.

One thing I have NEVER heard from anyone is that the Prevost A/C didn't work, and work well. Perhaps too well. But, I tell you when I limped into Las Vegas at 120+ outside the bus, and probably 140+ inside, I'd have given anything for Prevost OTR.

My two cents. As mentioned, your mileage may vary ....

The debate will go on but I like my OTR. It Vents thru the coffered ceilings,windows, & small vents incorporated into the backsplash in Kitchen and the two bath sinks. It returns thru slotted openings in the hall(at floor) between the Galley and Bath area. Keeps the entire Coach Climate controlled. The only down side I can see ; no speed control. One speed only on the two squirrel cage fans. Yes, I do not have two extra storage spaces but I am not taking my Golf Cart nor Harley with me.(Don't own them)
Country Coach has a 400 amp inverter & charger for their 2007 which allows you to run two roof A/C,s I believe. So, there are other good choices available.
Beats me what all the fuss is about. OTR was not on the top of my list for what I wanted in a Coach.

Might as well add my 2 cents to this thread. I have 97 Liberty with OTR. After spending over $2,000 in repairs and three trips to Prevost it's working great.

I was told by other Liberty owners that I needed the OTR system so that's what I bought. Drawbacks are the loss of two storage bays - Storage space is important to me as a full timer.

Ductwork along floor not really a problem as I have two sofas and they hide most of the ductwork except a section under the dinette table. In bedroom, ductwork along wall on passenger side makes it a little difficult to get arond the foot of the bed.

If I had to do it all over again I would opt for more storage, good cab air system and use the diesel Gen to run cruise air system while on the road.

Lee
97 LIberty 40' Classic

Despite all the blather that some converters have used to promote their idea of the best way to cool a coach I have developed some fairly strong opinions about what and why.

Remember, these are my opinions only.

I think the biggest arguments for OTR air are the ability to cool a coach quickly under any and all circumstances. Once a coach is cool, keeping it cool is less of a problem, but nothing matches OTR air.

If a converter converts a shell with OTR air the engineering and effort increases quite a bit. Without it you just install cabinets, walls and trim. With it you have to provide ducting and consider balancing air flow which is not as easy as it sounds.

If you do not have OTR, you probably do not want cruise airs. They will not work real well when trying to suck air over the condenser unit while driving because usually the highway is radiating some seriously high temperatures from the surface, and that tends to cost efficiency or even shut down the condensing unit on cruise airs. By going to roof airs you eliminate that problem and you are being consistent in addressing the biggest reason converters push their own version of air conditioning over the OTR system.

With no OTR or cruise airs you free up space behind the front bumper, some space in the center of the second bay, and some shallow space on both sides on the third bay. The net gain is probably the equivalent of a bay, but it is spread around the spaces described above.

There is sometimes an argument that OTR robs HP and roof airs or cruise airs run from an inverter do not. Not true. There are no free lunches and to provide the same amount of cooling when driving the load on the engine will be roughly the same, except in one case it will be a big compressor, and in another it will be an alternator.

Again, these are my opinions

Jon offered some good points about the Cruise Airs and there inability to work effectivly under extreem heat while motoring. Concidering my thread was directed at those who are still looking that was a oversite on my part when suggesting to opt out of the OTR

Because our bus does have cruise airs, it is probably better that we repaired the OTR A/C.

This Cruise Air topic, however, adds to my thoughts that if we ever move up the roof air units would be prefferable, in conjunction with drivers air only off the engine. We would not have the OTR A/C and going down the road the roof airs are not going to have a problem cooling. In addition they are easier to service, less expensive, more available when you do need one and frees up that additional space in the basement as well. For a 40ft bus 3 roof airs are going to cool it down pretty quickly in extreem heat. The only compramise in my opinion would be the looks and that is a compramise we would be willing to make.

Sure would have been nice to be a POG member before we bought ours.

Once your coach is converted it is going to be expensive switching AC sources. For example, in Joe's case he could physically remove his OTR and cruise airs, but unless he is prepared to run his generator while driving down the road, he has to insure he has inverter power to not only charge his batteries and run other things, but he has to be able to run at least 2 and possbile three roof airs.

For the record would someone please catoragorise the types of heat and air that you speak of in these posts. I think many names are for the same appliance.

If one has OTR/air does one have OTR/ heat?
Can you have one without the other?
If a bus is advertised as having bus heat will it also have bus air or must I ask?

Is bus/air one and the same as OTR/air?
Is bus/heat the same as OTR/heat?
If you do not have bus?heat where do you get your heat?

Is cruise air the same as roof air?

Do any of the rooftop units furnish heat?
Does Webasto heat go through the bus/heat ducts

Do the roof top units blow through ducts for a comfortable draft free environment, Or is it a powerfull drafty overhead stream?

If OTR/air is used while driving then when you require air when parked you must also have roof air,Yes? No? I don't think you get OTR/air when parked unless you run the engine?

Exactly how many heat and air source combinations are available?(relating to post 97 Liberty & Marathon conversions)? :confused: :confused: JIM

With OTR air you get OTR heat.

I assume if you do not have OTR air the bus still has a whole bus Prevost installed heating system. Can someone verify?

Bus air, Over The Road air are the same thing in the context of these discussions. Precisely it is a whole bus air conditioning system with the large Carrier (York) compressor, and the third bay on each side containing the AC condensing coil and evaporator coil. Whenver the engine is running the OTR air can be used for cooling, but if parked for any length of time the other systems are generally used powered by shorepower, the generator, or in ssome instances batteries.

Cruise Air is a brand name for an air conditioner that has a separate condensing unit (usually remotely mounted behind the front bumper and in the center area of one of the bays), connected to a remote evaporator unit, typically mounted in the living area out of sight but ducted as required. The condensing units usually draw air for cooling beneath the coach. When the bus is parked this is good because the air is drwan over a shaded surface. When the bus is moving, however that may pose problems because the highway is usually in the sun and is radiating heated air which may affect the ability of the Cruise Air unit to function properly. The Cruise Air units are closer to commercial quality and use heat exchangers and components such as might be found in commerical refrigeration products.

Roof air units are usually the same units as found at Camping World and which might be found on everything from a pop top camper to a conventional motorhome. They are inexpensive but will generally have the same output as a Cruise Air. Where the roof air units excel is they are getting fresh, cooler air when the bus is in motion, and they are inexpensive so repairs or replacements are cheap. Further, you can probably get one at most RV dealers.

Roof airs may be ducted, or may be dedicated to a specific area on a coach. That decision is up to the converter.Some roof units are provided with electric heat strips so in addition to cooling they can be used for heat. Both roof airs and cruise airs can be heat pumps which makes them suitable for coach heating and cooling down to around 35 degrees. The heat strips will heat at any temperature. Drafts and other issues are present with Cruise Airs or rooftop units and is dependent upon the converter and how they ducted and installed the units.

Webasto heat is another system, unrelated to the AC systems. Webasto operates by heating engine coolant which is circulated through not only the bus engine, but heat exchangers located throughout the coach and controlled by thermostats.

There are typically multiple environmental systems in our coaches. On my first Liberty I had OTR air and heat, and three Cruise Airs that were AC only. For heat I had 3 propane furnaces, four electric heaters (toe space low profile) and to supplement the bus heating I had at least four auxiliary heat exchanges that used engine coolant as a heat source.

The current Liberty has OTR, four Cruise Airs that are also heat pumps, two electric toe space heaters, and the Webasto system with multiple heat exchangers (at least 5). As you can see we not only have flexibility, we have backup redundancy and each source of heat or cooling has its optimum time for operation.

I hope other owners with differnet conversions will chime in here.