Advice on 1 or 2 AC units on 28' Airstream

[m.hony]

The cost difference between 2 a/c units and 1 a/c unit can't be much on an $80,000+ trailer anyway.

[Inland RV Center, In]

Originally Posted by switz

Since the physical size of the 13.5K BTU air conditioner is the same as the 15K BTU air conditioner and the power requirements are pretty much the same, one could swap out the lower capacity rear unit and have both units the same.

We will see if the stock 13.5 K BTU air conditioner is adequate this summer on the 23D and could always upgrade to the 15K BTU air conditioner.

In an average home, one ton of AC (12,000 btu) is good for 600 square feet or about 4800 cubic feet.

However an Airstream trailer is not insulated as well as a home.

A 30 foot Airstream has about 1200 cubic feet.

But since the insulation is far less than a home, many more btu's is required to cool the trailer down to the typical home temperature of 76 degees.

The compass heading when parking an Airstream, is very important when the AC will be used. Parking it heading east or west will expose the least amount of the trailer to the sun, at any given moment.

Keeping a good comfortable temperature also depends on when the AC is turned on. Cooling the trailer, before the interior temperature rises above the comfort temperature, is very important. In that way, the AC has some what of a lessor cooling job to do, in that you gave it a HEAD START.

A 13,500 AC is about 1 1/8 ton. A 15,000 btu unit is about 1 1/4 ton. Picking up that other 1/8 ton (1500 btu) sometimes is just enough to get the job done. However, on a very hot day, say above 90 to 95 degrees, additional cooling becomes almost a necessity.

Having 2 13,500 btu AC's or 2 15,000 btu AC's will absolutely do the job.

But, power requirements then becomes a big issue. Ball park, each AC unit will consume about 15 to 18 amps (1800 to 2100 watts) when running at a cooler inside temperature. The higher the interior temperature, the greater the wattage consumed. Unfortunately, the trailer has a limit of 3600 watts.

The very best way to then have 2 AC's that will run OK, is have the original unit "as is". Then, have the second unit wired so that it in "no way" is a part of the trailer power consumption. Simply have it wired totally by itself. In that way, at most camp grounds, you simply plug in the second power cable to a second outlet. Most campgrounds today have more than one outlet serving each parking space.

In that way, you still can enjoy all the other electrical things in the trailer, without blowing a circuit breaker.

Andy

[EarlM]

buy the two if you need it you have it if you don't just run one air, last summer we were north Carolina and it was hotter than the blue blazes and the 2 ac's ran most of the time

just my 2 cents

Earl

[m.hony]

Always better to have it and not need it than to need it and not have it-

[Texastex]

I have a 34 foot airstream excella with a 15,000 BTU Coleman air-conditioning unit at 108° in Georgetown Texas it work just fine with my small awnings out in a semi-shaded spot. It might not have worked as well if I had a bunch of guest going in and out the door all the time but we were comfortable with that one unit. Your use and number of people you carry with you may affect your decision. Many of the campgrounds I use are 30 amp harder run 2 the air-conditioners on that.

[Roadtech]

In the new Airstreams with ducted air, I assume both air conditioners share the same duct system. Therefore, unlike the non ducted system with one air conditioner, you get air distributed throughout the trailer. l wonder if most proponents of two air conditioners are experienced with the older non ducted systems and the real advantage then, was getting better air distribution by having air coming out of the two units in the front and rear of the trailer. Seems like with one 15,000 BTU unit blowing into a ducted system, distributing the air throughout the trailer, it would be adequate except in the most extreme conditions, which would be rare. Plus, with one unit, you get the advantage of less initial cost, lighter 30 amp cord, and the additional front 30 amp connector for a generator.

[switz]

Heat load is heat load. Cooling necessary for a 31' Airstream in the Southwest requires more than a single unit on a hot day wen parked in the sun.

So perhaps the location of the trailer during the summer is more of a determining factor for one versus two units. If the unit spends the summer in northern Michigan where the hot days can be int he low 80s, then perhaps one is adequate.

Resale down the road will be better wth two units in the southern tier of states. The extra $2,129 (in 2014) was not that much more when spending nearly $100,000 on a new unit.

[Rich Jenkins]

^^^ This.

I am SO glad we got two ACs. Heck, we had them both running here in Fort Stockton yesterday, and it was only 82.

[Howard L.]

Originally Posted by Roadtech

In the new Airstreams with ducted air, I assume both air conditioners share the same duct system. Therefore, unlike the non ducted system with one air conditioner, you get air distributed throughout the trailer. l wonder if most proponents of two air conditioners are experienced with the older non ducted systems and the real advantage then, was getting better air distribution by having air coming out of the two units in the front and rear of the trailer. Seems like with one 15,000 BTU unit blowing into a ducted system, distributing the air throughout the trailer, it would be adequate except in the most extreme conditions, which would be rare. Plus, with one unit, you get the advantage of less initial cost, lighter 30 amp cord, and the additional front 30 amp connector for a generator.

The ducted air in the double ceiling will lose some of its cool just getting into the trailer. Then the double top will provide better insulation also. So it might all be a wash. Fact remains that a 28 foot Airstream sitting in 100 degree sun needs two.

[Rich Jenkins]

Just a data point for the OP.

We are in Mesa AZ. It is 88F at 2PM and sunny. We are in full sun, with all the awnings (rear, utility side, patio side) awnings fully deployed.

Our 27' FC FB has 50A service, however our second AC is not working (separate issue).

Our main AC is working continuously, and the temp in the coach is 79 in the back and 81 in the front.

[Big Thunder]

Just a quick note about these A/C units: The difference between the 13.5 and 15k btu
units is more hype from the manufactures than reality! What difference between the outputs of either unit is minuscule and the numbers are only used for sales purposes. I've been involved in A/C repair for over 45 years and also designed A/C systems for the Prevost Busses. Put both units side by side and I employ anyone to tell the difference. The important thing is to keep the condensers and filters clean so as to get the maximum performance possible.

[Big Thunder]

Good review Andy. Here was my reply about dual A/C units.
Just a quick note about these A/C units: The difference between the 13.5 and 15k btu
units is more hype from the manufactures than reality! What difference between the outputs of either unit is minuscule and the numbers are only used for sales purposes. I've been involved in A/C repair for over 45 years and also designed A/C systems for the Prevost Busses. Put both units side by side and I employ anyone to tell the difference. The important thing is to keep the condensers and filters clean so as to get the maximum performance possible.

[Acheron2010]

I don't know about the 28's, and have not experienced "dry heat." In my 2019 FC26, in high humidity Tennessee, full sun, 99 degrees outside, awnings deployed, one AC unit can bring the entire coach to 70 degrees. I have two, but so far have not needed two, but glad I have the redundancy.

[emdubyadee]

We are planning to add a second A/C to our 2007 27FB because one is not adequate in the summer in the South. I have a question for those of you with two non-ducted units in your Airstream.

How loud is the noise level with both units running? If you want to watch television or have a conversation is it difficult if both A/C’s are running?

[brick1]

Get the 50 amp/dual air. We have a new 50 amp 28 foot Serenity. In our driveway we can only run one ac unit. Not enough. Don’t even consider a 30 amp unit.
brick

[uncle_bob]

Originally Posted by emdubyadee

We are planning to add a second A/C to our 2007 27FB because one is not adequate in the summer in the South. I have a question for those of you with two non-ducted units in your Airstream.

How loud is the noise level with both units running? If you want to watch television or have a conversation is it difficult if both A/C’s are running?

Hi

With the ducted AC, noise level is not very bad at all. One *nice* thing noise wise is that if it does bug you, run the one in the "other end" of the trailer. We do that at night. About all you need is a small fan to keep the air moving and it works pretty well.

Bob

[Re-Pete]

Originally Posted by KEIZER

A lot of variables there. BTU of unit, trailer layout, and are they utilizing factory insulation. I am removing my roof top unit and installing a concealed unit. Less wind drag and will look better.

Interesting. Can you offer more details on this and maybe a link or two.
Thanks