It is unusual that we get up to over 90F in the San Jose Bay Area. But it looks like that will be the case this week according to the forecast and most interestingly it is only May. So this is perhaps another proof that global warming is real. If you are reading this you are probably in the market for a residential air conditioner. Similar to furnaces, there are a few factors besides brand you should consider when you pick out that perfect system for your home. They are efficiency, capacity, staging, and refrigerant. We will go over efficiency in this article.
Just like you measure automobile mileage by miles per gallon, you measure residential AC efficiency by SEER (Seasonal Energy Efficiency Ratios). In short, it measures how much cooling effect in Btu/h your cooling system provides per watt of electrical consumption. The higher this SEER ratio, the more efficient your system is. As of January 2006, the US minimum standard for residential AC equipment is 13 SEER. This is an increase from a minimum of 10 SEER prior to 2006. The difference of a 13 SEER unit and a 10 SEER unit as you may tell is a 30% improvement in efficiency.
Most manufacturers make equipment with efficiency ranging from 13 SEER to about 20 SEER. It is important to note that the more efficient the system is, the larger the outdoor condenser AND the indoor coil are. So part of the considerations is the space available at your furnace or air handler AND your backyard location where the outdoor unit goes. And when a contractor tells you they are installing a high efficiency system, make sure they are using a matching coil that provides the advertised efficiency. Otherwise, you may be paying for extras that you don’t benefit. For example if your furnace is in a tight closet 13 SEER may be all you can squeeze out because of the indoor coil size constraint. Have an HVAC professional evaluate your situation and ask for the official ARI test rating for the condenser coil combination if you are in doubt.
We will continue the topic next time on capacity.