How much should an air conditioning system cost?

How much should an air conditioning system cost? It’s a question we hear a lot, being in the business we’re in, and it’s really very difficult to answer. We do know that it tends to be lower in Illinois than in, say, Texas, but if we say, “Well, look, on average you’re going to come out a shade under $4,000,” then how much have we actually told you? Because “on average” means…what, exactly? How big is the house? How many rooms and how many floors? And what system have you decided on? Because that $4,000 figure probably relates to installation of a central A/C unit – you might pay less than a tenth of that for a window unit to cool one room.

So let’s start by looking at the systems available. (We won’t go into great detail on any of these – they each deserve their own blog post and we’ll get to all of them in the coming months).

Cools the whole house, using the same duct system as the heating system uses.

Two separate systems, one inside the house and one outside. Can be ducted in the same way as a central system, or ductless.

Can be moved from place to place in the house. May be a split unit as above; alternatives are hose systems and evaporative systems, though an evaporative system is best suited to very dry areas and is not the obvious choice for Illinois.

A single unit that fits in a window and cools only that room.

Clearly, one important factor in choosing an A/C system is price. If you tell us we have to bring it in under $500, we’ll know there are some options that can’t be pursued. If the budget is more flexible, the next thing we need to look at is the size of the home. Getting this right is important because, although a larger house will need more cooling, too big a system cycles on and off frequently which wastes energy and makes a noise you’d rather not have. On the other hand, a system that’s too small will run all the time and won’t give you efficient cooling.

To prepare a cost estimate, our technicians will measure the rooms to be cooled, but they will also take account of other factors – insulation, building materials, number of windows, exposure to wind and sun among them. The next thing is to think about EER and SEER – that is, Energy Efficiency Rate and Seasonal Energy Efficiency Rate. SEER wouldn’t matter if you lived in, say, Panama where the temperature stays much the same and the only things that mark out the passing of the months is whether it’s dry season or wet season, but our customers live in Illinois where summers can be very hot and winters can be very cold.

The EER tells us how efficiently a unit cools the air and we calculate it by dividing the rate at which the air cools (in BTUs, or British Thermal Units) by the rate in watts at which the unit uses energy. Taking db as dry bulb and wb as wet bulb, we’re looking as an ideal for about 80 db and 67 wb inside and 95 db/75 wb outside.

We arrive at the SEER figure by dividing the cooling output in winter by the electrical input in winter and the higher the figure, the more efficient the unit is.

Those EER and SEER figures matter because they enable us to tell you which units will most efficiently cool your home.

No, we haven’t. Because, without coming to look at the house or office building you want the system installed in, we can’t. But we’ve told you some of the things that will affect the price. Others will include:

• Is there ductwork already in place, and does it need any work?
• Does the ductwork dictate what kind of unit can be used? (And what kind cannot?)
• Is there anything about the building that will make a clean airflow more difficult?

If you’re ready to take this further, get in touch and let’s get one of our people out there to start the measuring and pricing process.