Adding third roof air conditioner, fitment question.

[sofar-sogood]

Currently our 03 Beaver Patriot has 2 roof air conditioners, both are the Dometic Penguin 13,500's and are ducted into the center duct on the coach. There are (6) 6" X 6" ducts running front to back. There is a roof vent near the center of the coach that I would like to add another a/c in. The potential problem is that there is only 2 3/4" between the passengers side of the vent opening and the hallway wall. The existing duct work is approx 5" away from the drivers side of the vent opening. I am trying to learn if there is a a way to make the third a/c work either by adding it to the existing duct work or use it non-vented. My concern is that I would have to add more vents to the duct plus add duct to attach the new a/c to the existing duct work. Since I only plan on using the 3rd unit when in high temp environments, I think it would be easier to install a duct less model but I have only the 2 3/4" space to fit the inside plastic air return. I called Dometic who told me to call a dealer who said that they were booked for 2 weeks. Anybody got a solution? I have approx 19" width to work within the hallway.

[sofar-sogood]

Exactly, we have a 10 KW genny but I doubt I would run all the a/c's on the genny much at all even though the 10 KW would handle it. The Phaeton had a 12.5 KW with 3 15,000 a/c's and we were never too hot. I think I found a Dometic penguin that has a 17" X 17" inside grill that will work....hopefully.

zmotorsports wrote:
With our last coach we had two 13,500 Dometics and I replaced them with two 15k units. Couldn't tell a huge difference, very slight if any better. That was a 38 1/2' Beaver Contessa with NO slides. If I turned the A/C on earlier in the day the cooling units could keep up for the most part and keep us somewhat comfortable. If the ambient temperature would get into the mid-90's or higher and we didn't turn them on until we returned from sightseeing or a day playing in the sand dunes, forget about it, it was not going to pull all of that heat out of the coach.

When we started looking to upgrade in 2006-2007 we had an unusual requirement, we wanted to stay with a maximum length of 40', I wanted triple roof airs with a 10k genset. Almost impossible to find. Once you go to 42' and up triple roof airs and the larger gensets were pretty much standard. We lucked out and found a 40' with the Onan 10k and triple roof air conditioners that the original owners had special ordered.

What a difference! Now even with three slides adding cubic feet of interior space, we can turn on the A/C units in the heat and within an hour or so we are turning them down because it is getting too cool inside. Love the three roof air units.

Mike.

[zmotorsports]

With our last coach we had two 13,500 Dometics and I replaced them with two 15k units. Couldn't tell a huge difference, very slight if any better. That was a 38 1/2' Beaver Contessa with NO slides. If I turned the A/C on earlier in the day the cooling units could keep up for the most part and keep us somewhat comfortable. If the ambient temperature would get into the mid-90's or higher and we didn't turn them on until we returned from sightseeing or a day playing in the sand dunes, forget about it, it was not going to pull all of that heat out of the coach.

When we started looking to upgrade in 2006-2007 we had an unusual requirement, we wanted to stay with a maximum length of 40', I wanted triple roof airs with a 10k genset. Almost impossible to find. Once you go to 42' and up triple roof airs and the larger gensets were pretty much standard. We lucked out and found a 40' with the Onan 10k and triple roof air conditioners that the original owners had special ordered.

What a difference! Now even with three slides adding cubic feet of interior space, we can turn on the A/C units in the heat and within an hour or so we are turning them down because it is getting too cool inside. Love the three roof air units.

Mike.

[sofar-sogood]

Thanks for all the replies, I appreciate your help. The a/c's are working properly with 55 degree air coming out of the vents closest to the units, its just not enough cooling capacity for my liking when we are in hot areas. The coach is wired for a 3rd a/c in the hallway vent location so wiring isnt an issue, just the relative distance to the passengers side wall and the # of existing vents to handle the increased airflow if the 3rd unit were to be ducted. The coach is painted in dark colors which dosent help. Prior to this coach we had a 42 Tiffin Phaeton with 3 15K ac's and it did a good job at cooling even in summer at Las Vegas. This one is adequate unless the temps go above 90 then I would like to have the extra cooling capacity to cool the interior to 72 or so. I just think for the relatively small cost of another a/c that it would be worth it not to be uncomfortable without the use of additional air circulating fans. I have installed and replaced roof airs and have a forklift so I dont see the downside to adding another cooling unit since the wiring is already in place.

[jerseyjim]

Without a major re-wire, you won't be able to use all 3 at the same time....even then, the "normal" campground pedestal won't be able to supply the current. Most likely, neither will your generator. With few exceptions, everything is designed and wired for 2.

IMO, if it gets THAT hot...the simple solution just might be one or two fans to move the air around. Only once, with my motorhome, a heat wave in New York State, the temp was over 105. On generator, both my units were cranking fully, but most any a/c unit(s) can only cool like 15 degrees under the outside temperature. Even a house central air unit.

We were on the generator because the power at the campground went down (due to the heatwave)....brownout or complete stoppage....so we spent alot of time that day at the pool. And, as a sidebar, the generator and the a/c units performed flawlessly. But again, there's only so much they can do under such extreme heat.

[farmer_boots]

I have the same problem. Here in Florida it gets hot in the summer and the two 13K BTU units I have run all the time and just make it cool enough. There is no margin so for me a 3rd unit is an option. Thought about replacing them with 15K but you only gain 4K of additional cooling. A 3rd unit give me 13K and some backup. Don't know about your wall problem my center vent is dead center of the hall. The biggest problem is routing power to the unit. Will have to figure out what phase one AC is on with the Micro and use the other for the third AC.

[vance]

I took out a 13,500 and put in a 15,000 and can not tell a lot of difference when it's above 100 degrees. The oscillating fan will work just as good as far as I'm concerned.

[Dick_B]

Add a floor circulating/oscillating fan and forget the 3rd A/C.

[down_home]

Hummm. I'm not tickled by the level of heat rejection by our two units either. One in front is only 13,500 Main one is designed by the same guy that designed F 15's afterburners, judging by the noise.
Let us know how it turns out. 🙂

[Peralko]

How long is yoour coach? Even though some Country Coach 42-foot units were equipped with only 2 AC units, many had the center vent prewired for a 3rd unit--Beaver built good coaches--yours may have the same set-up. A good reason for have 3 roof ACs is you have back-ups ifone shuts down. The only time we used all our roof ACs, we had 120+ temperatures in Las Vegas. We have replaced all 3 AC units with 15,000 BTU units--We don't anticipate getting hot!;)

[lunch_surfer]

sofar-sogood,

I just added a 3rd ac to my 05 Mandalay. I wired it separately and kept it separate from the existing duct. I used a Colman Mark with local controls and discharge. The purpose is to drop the temp regardless of any condition to cool the coach. Also this unit is a heat pump in cold weather it helps keep us warm. Only negative is the unit is taller outside then the current Penguins, other than that perfect......

ctc

[Sprig]

sofar-sogood wrote:
Currently our 03 Beaver Patriot has 2 roof air conditioners, ...

First, I'd ensure the roof channels for the existing air were 100% clog free ... given the age of the coach.

Second, I'd OPEN every A/C vent to the max, or, even remove the fancy plastic crappy deflectors.

I was surprised to find out that by trying to direct the air flow from the over head A/C duct-work I was actually limiting the overall air flow.

I removed the directional vanes on the overhead A/C duct-work and my RV got a WHOLE LOT COOLER.

[Ivylog]

I'd start by replacing the one in the front with this 15K heat pump. This way you will have a spare 13K if you can find room for it in your garage.:B Thanks for selling me the toilet you removed so I'll never have any problems with mine.
He already has a hole/vent for the third unit, but not much room for the inside ceiling assembly.

[Lobstah]

Or upgrade one to 15K, see if that does the trick. I too am surprised that the two units don't cool your coach...I go along with the service idea.

Jim

[avidude]

Why not change your two exiting AC units to 15,000BTU models. Yes, you have to buy two units instead of one, but then you dont have all the customizing costs.