Air Conditioner under deck - lack of circulation affects efficiency?

[Paul]

Hi there,

When we moved into this house I noted the Air Conditioner was set under the deck. Moving it is not an option because of the property line, however I've been considering "channelling" the air that the fan blows out of the top away from the sides where air is sucked in to improve it's efficiency.

HOWEVER, although I am a pretty technical person, I don't know how home AC actually works - I THINK (at a very high level) cold air is "separated" from warm air somehow, with the warm air coming out of the top & the cold air entering the house. If this is the case, then channelling the "hot" air from the top of the AC unit away from the sides would be good.

On the other hand if this isn't how it works, then I might just be making the fan work harder for no reason.

I'd be grateful if someone could provide me a bit of a technical explanation of how home AC's work so that I can act accordingly & reduce the energy consumption of the AC.

[Edwin Pawlowski]

Good idea.

No exactly how it work, but you have the right idea. There is a refrigerant int he system. In half the system it is liquid, in the other half it is a gas. If youspray a can of paint did you ever notice how the can turns cold if you srpay for a long time? This is what is happening inside a closed system. The coil inside the house is cooled and as air blows across it, it picks up the heat from the house and the refrigerant inside absorbs the heat. Then it carries out the heat to the outside unit where it is carried away. The faster and easier you get rid of the heat the better. The outside coil is hot and the fan draws outside air over the coil and blows it out the top. The more heat you can get away, instead of going back onto the coil, the more efficient the sytem will operate.

It won't work any harder if you only direct, but not constrict, the airflow. A baffle of some sort may be all that is needed, or a grate in the deck floor, etc.

Do a Google search on refrigeration and you will find plenty of diagrams fro very simple to very complex. Many people don't comprehend heat transfer and they can cause their own problems. You seem to be on the right path and willing to find out. Remember, there is no such thing as cold. You can't make cold. You can only remove heat. Once you grasp that. concept, you are on your way.

[Paul]

[davemac]

Maybe you can add a steel grate grill to your deck above the unit to provide the exit port? If the ambient temp created around the condenser is much higher than it would be if the condenser was placed in open air then yes your efficiency can suffer since the compressor has to stay on longer in order to remove the heat. IE. you're slowing down heat transfer if the delta temp between the condenser coil and its ambient has decreased. It also results in higher head pressures in the system which can lead to premature failure due to leaks and wear and tear on the compressor. It's equivilant to having the condensor coils clogged up somewhat.

dave mc

[Paul]

A grate would be a bit better probably, but the supporting 2x6 boards that hold the deck up form natural "channels" to move the air away - what I think I will do (next spring!) is prevent the warm air from deflecting off the undersurface of of the deck back down to the sides of the AC unit by cutting an AC sized hole in a 4x8 sheet of particle board and suspending that under the deck -won't be visable, so issue with my wife ;o)

A picture would be worth a 1000 words here, but essentially I'll direct the hot air into the channels between the 2x6 boards & out the front of the deck.

A grate might be more effective, but I don't want one on my deck!

davemac wrote:

[Bob]

If you do try to redirect the exhaust air, take into account the prevailing winds, if any, during the usage season.

Bob

[udarrell]

Call the dealer for your equipment & explain the problem. They will tell you what the clearances are & most say NO ductwork or anything that can generate static pressure on the fan! On a top air discharge condenser a specific amount of clearance above the unit is required! - udarrell

[Stormin Mormon]

If the hot air is dumping under a deck, please consider a fan (atached under the deck) to blow the hot air out from under the deck.

Channeling or ducting the hot air from the top of the unit out from under the deck is also a good idea.