Wondering if it's true, or an old wives tale.

My AC condensor is on the SW side of the house and in the sun all day.

Does it really matter that the temp. in the shade would be cooler than sitting in direct sunlight?

I understand that un-restriced airflow is important, but I'm wondering if I put a small shade tree 10-feet away from the unit to block some of the sun if that would make any difference?

The importance is temperature differential and during July/Aug, the shade can be 10° or more cooler than direct sun.

[This message has been edited by agracer (edited 4/30/2012 12:17p).]

I recall reading that a shaded compressor made no difference in the efficiency or performance of the system as a whole, but I can't remember where and a quick Google search doesn't bring up anything familiar. I had thought of building a shade structure for my condensor but abandoned the idea.

That's funny. I thought I had read that it did help, but it may have been on a website promoting a product to shade your compressor. I also can not find a website.

Seen mixed stuff online as well.

I understand the theory of cooler air into the unit gets better efficiency, but just how much cooler is the shade? I guessed 10° above but the whole outside system is very hot anyway.

I'd say a clean compressor runs better than a shaded compressor.

[This message has been edited by AgDrumma07 (edited 4/30/2012 2:10p).]

Just make sure your coils on your condenser are always clean. Only use a water hose to wash out any dirt or grass never use coil cleaner on your condenser coils.

Shade helps, but only if you can actually get the air going into it cooler.

The way the system works is that you are rejecting the heat from the inside of your house outside. In order to move the maximum amount of heat to the outside, you want the largest delta T (temperature difference) you can get. By using warmer air, you are minimizing the delta T you can provide.

So...at the end of the day, if you were to have the outside unit in the shade all day vs in the sun all day, the shade should be more efficient (aka, not run as long).


The biggest thing you can do is minimize the HEAT GAIN to the house to reduce the cooling needs. By doing this, you will end up running the unit less, which makes it cheaper.




An analogy of this would be as follows: Your heat gain is 10k BTU/hr (large, I know). Your AC only moves 8k BTU/hr. So...eventually you will heat up the inside, until the sun goes down and your heat gain drops to under 8k (and lower), so the AC will "catch up" and remove the heat.

Now, if your heat gain was only 8k, the AC would have to run exactly as long as you gain heat (when the sun is up).

If the heat gain is less than 8k, then you AC will run for a while, then stop.

As you can see, the final situation is where you want to be (on some level; a constantly running system is more efficient use of power and would help with the life of the unit, but that is a different discussion). The shading vs not shading affects the amount of heat the unit can reject. But that would be something like 8k vs 7.8k per hour.


We should have a sticky with all the basic info for the summer.....

~egon

[This message has been edited by Dr. Doctor (edited 4/30/2012 3:37p).]

Dr.,
Too.many.words!

In summary:

Having it in the shade can help, but only marginally.
Keep your condensing coil clean.
Size your system correctly.
..............
profit?????

what do you think about the AC "misting" systems?

What is an AC misting system? Like spraying water out to cool people?

there is a system that constantly applies mist to the condenser coils. It allows for evoporative cooling at the condensor coils, thus helping get a larger delta-T at peak load in the middle of summer.

Not a bad system if you have high quality water. They can have negative effects on the coil if your potable water has alot of impurities. This can cause scale to build up on the condenser coil, causing a bigger problem than if you just left it alone.

I would venture to say that most of the outside coils are meant to handle the occainsional water (rain, hose, etc.), but a constant stream of water would cause issues. As stated before, hard water or water with large amount of dissolved solids would eventually build up on the surface of the coils. This would lead to either premature failure (erosion) or scale build up. In order to remove the scale, you could pop a hole in cleaning it during the winter months.

If you are that concerned, you can get a water cooled condenser. The size for a 1 ton unit will surprise you (it is about the size of a super mini keg of beer from the store). Only issue...gotta use treated water and it is once pass. I would think your water bill might take a little hit.


One potential option I could see is having a shaded area for the condenser, with a misting system that is not ON the system, but around the AC. The misting system (similar to the ones at Six Flags and such) would drop the air temperature around the unit (along with the shade) and give you a bigger delta T (drop the incoming air temp by 10-20 F). THAT might help out in the hot parts of the summer, but it is more of the issue of "How much for the setup ($$$$) vs running a slightly larger fan $$)".


As I have learned at work:

Water cost money. Air is free.

Prevent the heat from coming in and the AC won't work as hard.

~egon

I had an old unit when I moved into this house and on really hot days, 100+, the AC would struggle to cool the house. I used to turn the sprinkler on it the hotest part of the afternoon and it would cool the house better. Even at that the electric bill was nearly $300. I finally got a new AC and it has no problem in keeping that house cool and I am not wasting water! Bill never gets over $200 now.

Having the sun shine on your unit versus not is approximately an extra 1000 Watts of energy being added to the condenser. Since the condenser is there to gather excess energy from the inside of the house and discharge it to the atmosphere, this represents an additional load on the condenser which will require it to work harder.

Therefore, in the event that you can shade the outside unit without restricting air flow, you are helping things. Your best bet is to place it on the north side of the house, where it will be shaded for free by the house.

quote:

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where it will be shaded for free by the house

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...or plant a tree for shade.

quote:

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Just make sure your coils on your condenser are always clean. Only use a water hose to wash out any dirt or grass never use coil cleaner on your condenser coils.

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And never ever use a pressure washer as it will fold the fins over tremendously decreasing the units efficiency.

NO on the misting systems. My AC guy told me to get the sprinkler head changed to minimize water and extend condenser life. Besides with our Texas humidity levels you better be El Paso-ish for evaporator cooling to work.