I have a new air conditioning system, but it’s still too hot upstairs
What can I can do about it?
This is a common problem with two story homes. Heat rises and cool air sinks. Zone control installation to redirect air to the correct areas can help to alleviate this problem.
Installing a variable speed furnace to continually move the air in the home (only about ¼ of the maximum of your blower) can even out the temperatures. We recommend a variable speed motor because it only uses about as much electricity as a 40 watt light bulb when it is in re circulation mode. A standard blower assembly running full speed 24-7 can cost as much as $100 a month to operate.
You could also have a restriction in the ducting system. We can usually camera the system and find out what the problem is. Often times the problem is merely a disconnect duct or a damper that has fallen shut.
What size of air conditioner do I need for my house?
Air conditioners are rated in btus, British Thermal Units, with 12,000 btus equaling 1 Ton. This phrase comes from the days when ice was used for cooling. One ton of air conditioning is equal to the amount of heating you would get from one ton of ice melting in a 1 hour period. There really is no such thing as “cooling btus” as it is a process of transferring heat. In cooling mode, your air conditioner transfers heat btus to the outside air leaving cooler air in your home.
Contrary to what most service technicians perform, proper sizing is not done based on the square footage of the home, such as one ton of ac for every 500 square feet. Such rough rule of thumb guesses do not allow for important variables. My only question to those technicians that guess at the size of the system in the home is: “Are you going to guess on how to properly install the system as well?”.
The proper size can only be determined from the results of a heat load calculation on your home. The calculation takes into account the area of exposed walls, the glass area and whether it’s single or dual pane, the insulation levels in floors, walls, and ceilings, any exterior or interior shading and the volume of the home in cubic feet.
We use a method of calculation called “manual J” which was developed by Air Conditioning Contractors of America, we are members, and this is the only approved method by all major building codes for sizing heating and cooling systems.
We use an abbreviated form for this (we don’t have a lot of the structural and surfaces that the rest of the nation does) and this process takes about 45 minutes to accurately size a system, faster with your help measuring. Yes, sometimes the system does come out to be 500 square feet a Ton, but generally, that figure is a little oversized.
Proper size is critical to you and your families comfort and savings on your energy bill. Oversized units cost much more to operate and short cycle so much that your house may become humid and uncomfortable. Undersized units run all day long and still don’t cool the house. Make sure you get the right size.