2 Acs-Does one area get much cooler than other?

[mikeinca]

Originally Posted by Piggy Bank

I am assuming that whether you run 1 AC unit or 2 AC units, that all of the ductwork is connected and that both units are feeding the entire trailer. I have not uploaded the parts breakdown and studied this.

If we want to get it to feel cooler in the front of the trailer where the beds are, what is the best way to do that? Have the AC over that zone set colder, close vents in the other end of the trailer, or something else?

Thanks for any advice. We are going out again next weekend so I can fiddle around with things then.

As you've assumed, all ductwork is connected and both units feed the entire trailer.

In our dual AC Classic I've found that the easiest way to make one end of the trailer cooler than the other, or to balance out airflow and temps between the front and rear is set both zones to the same reasonable temperature and then adjust the vents appropriately.

[twbucksr]

Those of you with two AC systems that are ducted must realize that they both use the same supply air ductwork and therefore communicate with each other thru that ductwork.

Therefore when one unit is on it’s pushing cold air down that ductwork towards the other unit.

If the other unit is off, the cold air pressurizes the ductwork and comes out the ceiling grills as it seeks the path of least resistance to travel back to the return/intake side of the fan in the unit it came from. It is possible that the path of least resistance for the cold air is through the other unit backwards and out the other unit return grills.

If both AC units are on, then this doesn’t take place.

Clearing the pathway in the return side of the unit is wise but what is more important for system performance is keeping your return grills and filters clean.

The design flaw is putting the larger AC over the kitchen when 2 ac units are used.

Because of noise, we run the smaller, bedroom unit during the day and our kitchen unit at night. Because the ac load is less at night, the larger ac cycles on and off all night which is less efficient and accelerates wear and tear ultimately shortening its life.

[mikeinca]

Originally Posted by lzhome

Question: my 2020 FC 27FB has two AC units, are they both 15,000 models? They both appear to be identical from outside view. Didn't get any documentation and looking for links to user manual.

Also, we have fewer AC outlets in the bedroom then the living area, this proably is why the temps are not atabe front to back.

The standard unit is 15,000 BTU. The second optional unit is 13,500 BTU. Typically, the larger capacity unit is located over the living/galley area while the smaller one is over the bedroom. You can verify this by removing the intake vents and using a flashlight to find the manufacturers label on the AC unit itself. The BTU rating should be printed on it; it was in my Classic.

[lzhome]

Originally Posted by mikeinca

The standard unit is 15,000 BTU. The second optional unit is 13,500 BTU. Typically, the larger capacity unit is located over the living/galley area while the smaller one is over the bedroom. You can verify this by removing the intake vents and using a flashlight to find the manufacturers label on the AC unit itself. The BTU rating should be printed on it; it was in my Classic.

Think this is accurate. Just checked mine and the bedroom "13,500" and the living area only has "NOM BTU: Hi Cap."

I did get the product numbers so maybe now I can find some online documentation.

Thanks mikeinca

[turk123]

Originally Posted by twbucksr

Those of you with two AC systems that are ducted must realize that they both use the same supply air ductwork and therefore communicate with each other thru that ductwork.

Therefore when one unit is on it’s pushing cold air down that ductwork towards the other unit.

If the other unit is off, the cold air pressurizes the ductwork and comes out the ceiling grills as it seeks the path of least resistance to travel back to the return/intake side of the fan in the unit it came from. It is possible that the path of least resistance for the cold air is through the other unit backwards and out the other unit return grills.

If both AC units are on, then this doesn’t take place.

You make a good point. The air from the front AC is finding itself a path through the off rear AC and out the return vents. It creates a wall of cold air as you enter the bedroom. I think I'm going to add velcro cloth flaps to cover the return vents and see if this balances the cold air more. In a Classic 30 there is a lot of cold air coming out of those two return vents. I run the front AC at night and I am up front working on the computer late. My wife goes to bed early and I freeze her out! Just have to remember to take the covers off when using the rear AC.

Also, the 2019-2020 classics have 15k ACs front and back.

[kellycox7]

Definite difference in A/C's with us. You can be freezing on one end, and burning up on the other. Seems one end has almost no air flow, in proportion to other end. I'm assuming they're the same size units, but the ducting system and coverage of one end is too large for that A/C.

[TKBoerne]

Our 27 ft FB twin A/C does the same thing. Always cooler in the back kitchen area. We also turn the front A/C down. Our problem is after awhile hot air starts blowing out of the front vents. Does anyone else have that problem and is that normal? What is the solution to that?

[robearl733]

I have the same problem with sensor location in a 2016 25FCFB Twin. I brought this issue up to Airstream Management and Engineering at the feedback session of the Alumapalooza last year. So they are aware of the problem. Someone on the panel said most likely the frig heat was culprit. Hope AS addresses. I blow a fan toward the sensor and set the thermostat temp higher for living area.

[mysprinter]

I also recently got a 26 Flying cloud RB with twin AC and I noticed that on the controller there are zones that allow you independent control each unit. Mine needed to be adjusted to get air into bedroom. Also the vents can be opened or closed to reduce air in one area or another

[mythbuster88]

Originally Posted by turk123

You make a good point. The air from the front AC is finding itself a path through the off rear AC and out the return vents. It creates a wall of cold air as you enter the bedroom. I think I'm going to add velcro cloth flaps to cover the return vents and see if this balances the cold air more. In a Classic 30 there is a lot of cold air coming out of those two return vents. I run the front AC at night and I am up front working on the computer late. My wife goes to bed early and I freeze her out! Just have to remember to take the covers off when using the rear AC.

Also, the 2019-2020 classics have 15k ACs front and back.

So did you do this and did it work?

With just the one AC running in the front (closest to the hitch) the rear of the trailer is much cooler, like 5-8 F cooler.