A/C Mode - Cool VS Dry

[The Woodieboys]

Are we the only ones that have noticed that using the Dry mode on our Roof top A/C units keeps the coach cooler than using just the Cool mode? We started using the Dry mode to keep the humidity level down in the coach but are using it all the time now to keep the coach cooler.

And it's not just a feeling thing either with the humidity level. It actually measures cooler by at least 2 degrees....

[Ray,IN]

Air conditioning was discovered by accident, the inventor was building a de-humidifier. Cold air output was a side-effect from the evaporator coil. It is possible to have too-large an air conditioner, which results in cold, clammy air inside. I suspect "dry" mode causes your A/C compressor to run more.

[powerboatr]

i run my aft unit in the low fan mode with the temp set at 77, it cycles the a/c compressor on as needed and keeps us fairly cooool
havent tried the dry mode, might have to look at it

[DBOL]

Quote:

Originally Posted by powerboatr i run my aft unit in the low fan mode with the temp set at 77, it cycles the a/c compressor on as needed and keeps us fairly cooool havent tried the dry mode, might have to look at it

Haven't tried Dry mode yet,but waiting for report from Powerboatr,by the way I went down in 2 and out in3 at Palo Duro Canyon.

[powerboatr]

Quote:

Originally Posted by DBOL by the way I went down in 2 and out in3 at Palo Duro Canyon.

much grass

[EngineerMike]

What AC do you guys have? I don't see Dry mode on my Dometic.

[powerboatr]

Quote:

Originally Posted by EngineerMike What AC do you guys have? I don't see Dry mode on my Dometic.

mine is a carrier air V
i am not impressed with them....
but i think its more on the installation than the unit.

on the hot days out in the sun both of them run and run plus i use a fan in the kitchen to help move the air

we really should have three vice two.

[The Woodieboys]

The dry mode on the Carrier V does a very good job of taking the humidity out of the coach, especially when you have water vapor in the coach such as taking a shower, doing dishes, etc.

We found the Dry mode by accident and I read about it (other posts on this site) and we run it most of the time now. It does a better job of keeping the 'large brown object' cooler on the inside.

As for three units VS two, I think we are fine with the two and have been in some rough 100 degree days in FL in the summer. What is the tough part is keeping the heat out of the coach from that large picture window that is the front of the coach. Catch 22 with it. If you can keep most of the heat from it out two units are just fine.

[powerboatr]

wife made a bid window screen last year from the foil insulation stuff from lowes and she attached a fabric of deer on one side and tropical fish on the other, it helps a BIG deal with reducing that heat
but it limits your frontal view when parked

[Leonsrocketcar]

my carrier manual says that dry allows the compressor to be more effiencient, and if so then why wouldn't we just have dry rather than a cool section? I too use a frontal sunblock, but when driving west in the heat of the summer, it reached upper 80s in my coach (with 2 fans running on the driver to help him out). The front carrier kicked a breaker, so we cut it off and ran the rear to pull it down to mid 80s inside.

Will try dry on the next run.

[jcthorne]

I have yet to figure out what the DRY mode does other than keep the fan running all the time rather than cycling with the compressor. If that's all it does, then it doing exactly the opposite. When the compressor shuts down, it blows damp air into the coach as the coils are wet and the now warm air passing over them brings the water back into the coach. If drying of the coach is what you want then the lowest fan speed for the longest compressor run cycles and then shutting the fan off with the compressor will accomplish that. For the low profile units with seperate condensor fans, starting the compressor first and then the evap fan once the coil is cold would help too but will not work on the regular units with single fan motors.

I could not tell what else the unit was attempting to do if anything in that mode and its not well documented by Carrier. Anyway, in the two days I ran DRY mode, it seemd better suited for DRY CLIMATES where you want the humidity back in the coach. IE did not keep the coach dry at all.

[The Woodieboys]

Quote:

Originally Posted by jcthorne I have yet to figure out what the DRY mode does other than keep the fan running all the time rather than cycling with the compressor. If that's all it does, then it doing exactly the opposite. When the compressor shuts down, it blows damp air into the coach as the coils are wet and the now warm air passing over them brings the water back into the coach. If drying of the coach is what you want then the lowest fan speed for the longest compressor run cycles and then shutting the fan off with the compressor will accomplish that. For the low profile units with seperate condensor fans, starting the compressor first and then the evap fan once the coil is cold would help too but will not work on the regular units with single fan motors. I could not tell what else the unit was attempting to do if anything in that mode and its not well documented by Carrier. Anyway, in the two days I ran DRY mode, it seemd better suited for DRY CLIMATES where you want the humidity back in the coach. IE did not keep the coach dry at all.

The mode is for the exact opposite of what you describe. We have very high humidity in Florida and dry keeps the coach much dryer in side than on just cool. And the amount of water that the compressors pull off the coach is much greater on dry than on cool. According to the manual dry uses the compressor much more efficiently.

[jcthorne]

Quote:

Originally Posted by The Woodieboys The mode is for the exact opposite of what you describe. We have very high humidity in Florida and dry keeps the coach much dryer in side than on just cool. And the amount of water that the compressors pull off the coach is much greater on dry than on cool. According to the manual dry uses the compressor much more efficiently.

Yes, I have heard this discription before but noone has been able to say what the unit is DOING differently in dry mode to be more efficient or to remove more water from the air. We run the Dry mode and can FEEL the swampy air coming into the coach every time it shuts down the compressor. The interior humidity is MUCH higher in DRY mode. I contacted Carrier at the 800 number in the manual and got nearly the same discription you gave but they could not tell me what the unit DOES in that mode to supposedly remove more moisture. I can tell you that in our limited experience of 95dg and about 60%RH, it seems to cycle the compressor more often and keep the fan running full time and blows wet air into the coach. The wife had no idea I was trying the DRY mode and asked why the coach was swampy feeling. In our use DRY mode did not help dry the coach. Perhaps if we had some understanding of what the modes DOES we could better apply it in certian climates. Perhaps it works in cool and clamy climates to dehumidfy somehow, but without a reheat strip, have no idea how it could do that.

[doc]

We ran our front Carrier for several days this past week. A couple or three of them were in the 'dry' mode. I really could not tell any difference in dry and cool, except to say the dray caused the fan to run at a continuous speed that could not be changed with the 'fan speed' button on the remote. Both dry and cool had water dripping off the roof and both cooled the interior of the coach well.
I have to suspect the only difference is the speed of and the way the fan is controlled.