Most Efficient AC

Chillbilly · 07-22-2012, 11:48 AM

Just wondering what the most popular AC setting is. Do you run the fan on HI, LO, or AUTO? And, has anyone found the best orientation for the AC vents on the 31Y Adventurer floorplan? I'm a new owner and am trying to get the best AC setup as I can. Any advice would be most welcomed.

MaverickBBD · 07-22-2012, 12:15 PM

I have a Journey 36G and have not noticed any difference between fan HI or LO. If pressed I would probably say the air is cooler on LO. If running the AC we keep the fan in AUTO.
Spent several years setting the vent orientation but still add additional fans. I found this keeps hot spots from developing. I hang a box fan (approx. 12 x 12) below the front TV. This removes the hot air from the windshield area and pushes the cooler air back toward the main salon. Then I set another box fan on the floor next to the bed between the blower fan (furnace) and air return vent. This seems to cut down on the harmonics of the second compressor and again blow cooler air back toward the main salon. Then I put a 5" fan on the night stand on the other side of the bed and this keeps the closet slide from creating a heat sink on that side of the bed. I also have an overhead ceiling fan in the bedroom that I usually run on low. I also have MCD day/night shades all the way around that when it gets over 100 I keep closed. If the wind allows I extend the 20' awning and have a 'drop' that adds additional shade.

This works for me. Like I said I have used my infrared thermometer and have done years of researching and experimenting. I advise you get one also and do your own checking. Also a roll of flagging tape and some scotch tape can help you determine air flow/movement.

wa8yxm · 07-22-2012, 01:04 PM

Many have complained about the evaporator icing up, Many feel it is an air flow problem (I happen to be in the minority there, think it's somethign else) but running the fan on HIGH may help to aleivate this problem..

The more air you move over the coils the warmer those coils will be, and the warmer they are the faster they suck heat out of the motor home. Thus HIGH is the mose efficient setting.

ON AUTO, the fan may run low, high or off, the frequent changes in noise can be very very annoying, Running it on HIGH all the time, your brain quickly filters to the point where I find it hard to hear mine at all. I actually have to THINK, Is it running before I hear it. Masks exterior noise as well.

motohomer · 07-22-2012, 01:25 PM

I just leave it in auto. The thermostat knows what to do.
And the occasional quiet is nice.

Point the vents where the heat is (the side the sun is on) for even-est coverage.
Also close your blinds to keep the sun (heat) out. And if possible,park under trees - but not low or sappy ones...

Chillbilly · 07-23-2012, 06:32 AM

Thanks for your views, Motorhomer. I thought I had remembered reading somewhere that the orientation of the vents had an effect on the best air-flow. I know some who keep their fan on all the time along with the AC during hot weather to keep the air circulated to avoid "hotspots". I thought maybe someone had done some experimental research to keep me from "re-inventing the wheel". Hopefully, others will chime in here and give their opinions and recommendations. Thanks for yours.

Chillbilly · 07-23-2012, 06:39 AM

Thanks for responding and giving your opinions and findings. I remember reading on some forum that the orientation of the vents effected the air-flow, but can't find it now. I have some friends who leave the fan on all the time along with the AC to keep the air circulated to avoid hot-spots. Other friends argue against this because of the wear on the unit. Maybe others will chime in and voice their opinions and findings. Thanks again.

TXiceman · 07-23-2012, 06:51 AM

Generally you will want all of the air registers open. The preferred oprion is to run the fan on high speed. There may be little if any noticable change in noise level to the human ear, but if the motor is wired correctly, there will be a difference in air flow.

Running the fan on low can cause the evaporator to ice. Spent 42 years in the industrial refrigeration field with some time working with A/C units. If you want, I can go to a long technical explaination of why low air flow causes a lower suction pressure which results in a lower temperature...but it does happen.

As for how to direct the air flow from the registers, what ever makes you comfortable. Just do not point one at a thermostat or a temperature sensor.

I like keeping the fan on manual so that the air is moving and it keeps the RV at a more even temperature.

Ken

Chillbilly · 07-24-2012, 06:45 AM

Thanks for your opinions TXiceman, your experience would make you an expert in my view. It seems the consensus thus far is to keep the fan on HI and leave it on all the time. I haven't heard anyone mention the wear on the AC unit by doing this. Thanks again.

TXiceman · 07-24-2012, 07:02 AM

It is a toss up for running the fan continiously or stoping and starting the fan. Starting an electric motor subjects it to stress and thermal shocks that it will not see until it statrs again. Leav it runnig and the bearings get extra hours.

As for the life of the unit, most of the time the unit wears out before you loose the fan motor. But a fan motor is not that hard to replace.

The down side of the continious fan is the nosie which bothers some people. I like the "white" noise personally. But some people are bothered by the fan starting and stopping.

So it boils down to your choice...what ever flips your fritter.

Ken

BCooke · 07-24-2012, 11:34 AM

TX Iceman,
Would that also apply to brass sleeved versus bearing? (I did not if you were saying just for bearings or meant sleeves also)

Jimooo · 07-24-2012, 12:14 PM

I would also like to add TXiceman, to our readers is to never turn your A/C off during summer months just keep your stat on 72' to 78' leave your selector switch on auto and fan on high.

You shorten the life of your A/C unit with a full load trying to satisfy t-stat, so manufactures recommend letting unit cycle instead of turning off and then on when needed.

Also never close any supply vents, your A/C system was designed for that amount of heat load in your coach, plus you can cause back pressure on duct system causing a split or , burn up your blower motor.

Happy RVing. , James

TXiceman · 07-24-2012, 12:48 PM

Quote:

Originally Posted by BCooke

TX Iceman,
Would that also apply to brass sleeved versus bearing? (I did not if you were saying just for bearings or meant sleeves also)

Nearly all of the small fan motors used on the RV A/C units are sleeve bearings with oilite bronze bushings.

Ken

Jimooo · 07-24-2012, 01:12 PM

And these small fan motors are to costly to re-build, cheaper to buy new, instead of re-sleaving .
Happy RVing , james

Chillbilly · 07-25-2012, 06:39 AM

Thanks to everyone who responded. I'm sure your information will help not only me but others reading these posts. I think Jimooo's instructions are right on.

"never turn your A/C off during summer months just keep your stat on 72' to 78' leave your selector switch on auto and fan on high"

Jimooo · 07-26-2012, 08:30 AM

Hey thanks,chillbilly for the compliment.

Happy RVing , James

Jimooo · 07-26-2012, 08:45 AM

Also I think that the dometic brand is rated high as far as heavier copper coil construction, they all use the same compressor maker Copeland scroll and just about all the same fan motors.

Don't get me wrong Coleman is good also, I just like dometic better and it is easier to work on.

As far as residential A/C units, the carrier infinity system is the highest rated , most efficient, and most reliable, well perfected unit also very easy to work on.

This is just my opinion.

Happy RVing , James