Building a New Home
& the Air Conditioning System

Air Conditioning is one of the most important considerations when you build your own home.


As I sit down to write this article it is 95 degrees Fahrenheit outside with 100% humidity. Around here in August you better have a good Air Conditioning System or you will be miserable.

I am not an HVAC Guru, but when I built my house I did my research and found a very good contractor to do the install. You may want to visit the Building Contractor page For more information on selecting a good contractor.

Back to A/C. I would like to walk you through my experience start to finish. I will break down the installation as I go, and share what I think will help you when you put in your system. My intention is to educate the Owner Builder, or those that are having their home built on the key points concerning your air conditioning system. Many of these came from hard earned experience, as you will see.

Ok, let's get started. You have chosen your air conditioning contractor.

Got your bids and selected the best one for your needs. Wait a minute, you say! How do I do that? Let me tell you how I approached the process.

First I selected the brand name I wanted to put in. Why? Because every dealer does not install every brand of system. I choose Lennox because I have had good success in the past with them. You may choose a totally different brand but choose up front.

Then I did my contractor Research and got three bids. The A/C Contractor will recommend what he/she thinks is best for your application. If you have any input into what you want it is a good idea to let them know up front in the Bid Package.

One important thing that you need to look at is SEER Rating. What is a SEER Rating?

Central air conditioners are rated on their seasonal energy efficiency ratio (SEER). The higher the SEER rating, the more efficient the unit. The minimum SEER rating allowed to be sold today is 10. Models with SEER ratings of 12 or better are recommended.

With that said you may have guessed the higher the SEER rating the more expensive the A/C system. What I did was have them bid my systems at 12, 13 and 14 SEER.

What I found out was above 13 SEER the prices of the systems jumped dramatically and the payout was going to be over 10 years. The payout is figured by estimating your energy savings by putting in a higher SEER unit versus what you save on electricity. Your Air Conditioning Contractor has tables that he can give you a good idea on this subject.

Now considering where I live, a system is only good for about 15 years it did not make any sense to spend the extra cash. A 13 SEER Air Conditioning System is what I choose.

One thing I want to stress here is the market is constantly changing in the Air Conditioning industry. Not to many years ago a 10 SEER System was considered very efficient. Another point is everybody has a different situation. Some people run their thermostat at 70 degrees year round, where others are conservative. The more you run your system with a higher efficiency unit the more you will save and the quicker the payout.

The next thing you need to look at is your house layout and how you will use your Air Conditioning System(s).

First let’s do a reality check here. In the past you may have just bought a house and moved in. The Air Conditioning System was already there, so you had no decisions to make. Now you get to decide what is best for you. I love it when this happens!

Also in the past you may have bought a house built by a builder, and his main concern was building the house as cheaply as possible. The Government has minimum standards for SEER ratings (thank God) or there is no telling what your power bills would be.

Now we need to look at our options a little bit. Take my house for instance. I have a two story with a master suite on one side of the house. I like it cool when I sleep, so I knew I wanted the master suite to be a separate system. No sense in cooling or heating the whole house at night. With this in mind I included this expectation in my bid package for my Air Conditioning project. When I got the bids back I knew I had more decisions to make.

The Air Conditioning Contractors all agreed that I need around 8 tons of total A/C for my home for cooling. Below is an explanation of a ton:

Ton -The unit of measurement for air conditioning system capacity. One ton of air conditioning removes 12,000 Btu's of heat energy per hour from a home. Central air conditioners are sized in tons. Residential units usually range from 1 to 5 tons.

One Air Conditioning contractor came back with a bid that split the house up with a 5 ton unit and a 3 ton unit. The only problem was the 5 ton was a split system setup. In essence the system would use 2 thermostats and air would be split between the downstairs and the master suite. That defeated my purpose of having the Master Suite being separate. In other words the contractor did not listen to what I wanted so he did not get the work.

Bidder number 2 tried to sell me units that were made by a manufacturer that I knew nothing about. Guess What? I did not use him either. He was cheaper but he did not hear what I wanted.

The Bidder that got the work came back with a system that meet my needs, and was reasonable in price, by the manufacture that I wanted. I have three separate systems. A 3 ton upstairs, a 3 ton downstairs, and a 2 ton for the Master Suite. All of this for a little over $1000 dollars a ton. Good deal right. Read on I learned some lessons.

Separate Air Conditioning Systems have advantages and disadvantages. One of the big advantages is you can heat and cool parts of the house at different settings. You can also do this with split systems that operate by using air dampeners controlled by a PLC card (computer).

My experience with one of these setups was not good, so I choose separate systems. I had a split system on our last two-story house and it never really worked right. It was supposed to cool the upstairs from one thermostat and the downstairs with another. Both upstairs and downstairs used the same Air conditioning system, they just had separate ducting. The challenge was the upstairs was smaller and the system would come on and not run for long, thus not removing adequate humidity for comfort. So you had to run the upstairs cooler. Making the house comfortable was a challenge. Anybody upstairs lowered their thermostat and the downstairs starved for air. It was a constant battle of the thermostats.

The disadvantage with separate Air Conditioning Systems is you have more system to break down. With that in mind you also have different systems so when one does break, you can stay in a different part of the house.

I guess we could debate what is best for years. In the end it is your house so you have to decide. Just take your time do your research and choose a good air conditioning contractor.

Ok, where were we. We have chosen a air conditioning contractor and we have a solid bid, and know what system(s) we are going to put in. This is what I wound up with outside after the install.

air cinditioning condenser units
The 2-ton is on the left and the other right and center are 3-tons. Can you tell the difference? Well if you can’t you are not alone. Now for a not so funny story.

The Air Conditioning contractor is like every other contractor. They install in stages with different crews that do different things. You can follow the whole construction process on the Home Construction Page.

One crew did the rough in of all the ductwork, another did the installation of the air handlers in the attic, and yet another put the outside condensing units in.

Well in the process they had a failure to communicate. The outside condenser installer hooked up a 3-ton condensing unit on a 2-ton air handler (or evaporator). Needless to say it caused problems. When we cranked up the units it was cool so I had no reason to run them for any length of time, but when it got hot out the fun began.

Without getting too technical, the 3-ton compressor was way to big for the 2-ton air handler (evaporator). So before to long the compressor loaded up and started making some really bad noises.

I picked up the phone and the air conditioning contractor came out and listened to it and said “yep that is a bad compressor in that unit” then they changed it. What is not too funny is they put a new 3-ton compressor right back in the unit, and it was still pumping into a 2-ton evaporator. In essence it took three trips and much of my anxiety to get it fixed.

Should the air conditioning contractor caught this up front? You bet they should have.

The moral to this story is make sure you use a reputable company that will stand by their work. Do your Research up front as detailed on the Contractor Page.

Ok, enough on horror stories of the Stevens kind. We need to talk a little about where to place your air handlers. Remember in the past you just took all of this for granted. It was there and you lived with it. Now you have a choice. Why does it matter?

I remember in one of our houses, when the air conditioner or heater came on you had to yell to hear yourself think. The air handler was mounted downstairs in the living room in a closet and it was LOUD! Why would anybody install it there? You guessed it. It was Cheaper!

The difference in cost to make you system quiet is almost nothing. In fact on my systems there was no difference. When the framing was up and we were ready to rough in the Air Conditioning ductwork the supervisor and I walked it out and made the decisions together.

I decided the best place for the air handlers was in the attic. The advantage of this is they are quiet up there. The disadvantage is they are harder to service and the water that is condensed can cause water damage if the air handlers are not set up properly. Now for a couple of illustrations:

air conditioning air handler

All my air handlers are essentially the same. I have marked three critical items you must pay attention to if you want to virtually eliminate the chance of water damage to your ceilings, when you install your Air Handlers in your attic.

The first is the Condensate Drain Line. All units have a drain line that should be tied into a drain. You should make sure they insulate this line all the way to the drain. If they do not insulate it properly it will sweat and drip on your ceiling eventually ruining it. Also watch carefully the first few times you run the unit for any leaks. My contractor missed gluing a joint and it leaked.

The second is the Overflow Drain Line. This line is attached to the drain pan and carries water out of the pan if the Condensate Drain Line becomes clogged or blocked. You should make sure this line is properly routed to the outside of the house and has a slight slope in it to make it drain correctly. One of the installers stepped on mine pulling it out of the wall. If it had not been corrected it would have drained into the ceiling.

The third is the High Level Shutdown Switch. In the event of the Condensate Drain line being blocked or plugged, and the Overflow Drain Line not draining properly the level in the tray will rise and cause the switch to shut the Air Conditioning Unit down. I have included an up close picture of the switch below.

air conditioning high level switch

It may seem like a little overkill but condensate can ruin your ceiling if it is not drained properly. Of course the other alternative is putting the Air Handlers downstairs or in a garage closet.

Let me sum up by saying choose your air conditioning contractor wisely. Take your time, and make sure you get what you want. The cheapest bid is not necessarily what is best for you in the long run, especially if you are planning on keeping your house for a long time.
For more Information on Building Your Own Home Go to Our Building Knowledge Center.

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