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High Efficiency Central Air Conditioners

Last week, I talked about air conditioner efficiency in terms of window air conditioners. In some situations, window air conditioners will work just fine. For some homeowners in Boston, central air conditioning is the preferred solution because it cools the entire house, instead of a single room or selected rooms.

As a brief refresher, the seasonal energy efficiency rating (SEER) compares the output of the air conditioner to the electricity it consumes. The higher the SEER, the more efficient the air conditioner is. A BTU (British thermal unit) is a measure of cooling output. The higher the BTU, the more powerful the air conditioner is.

For a “whole-house” solution, a central air conditioning unit with a BTU output of 60,000 and a SEER of 19.9 (very high efficiency) will consume about 3kW/hr. At $0.05 per kW/hr, assuming that your air conditioning is on for 8 hours daily, you’ll spend about $1.20 per day on electricity to cool your entire house. Over the course of a season (assuming 110 days), you’ll spend about $135 to keep your house cool.

If your central air conditioner had a BTU output of 60,000 but had a SEER of only 10.8 (the same as last week’s window air conditioner), the daily operating cost would be about $2.25 and the seasonal expense would be about $244.

Over the course of 10 to 15 years (the life expectancy of a well-maintained central air conditioner), you’d spend between $1,100 and $1,650 more on electricity to use the low-efficiency air conditioner. If you applied this expenditure to a higher-efficiency air conditioner instead, you’d save money over the life of the unit. You may also qualify for rebates or tax incentives by choosing a high-efficiency unit.

The lesson here is that if you want central air conditioning, install the highest possible efficiency system you can. The up-front expense may be larger, but your expenditure over the lifetime of the system will be lower and it will lower your total cost of ownership.

Also keep in mind that maintenance is a key part of extending the life of your central air conditioner and maintaining its rated efficiency. Without maintenance, an air conditioning system can lose between 5% and 10% efficiency each year. That would effectively transform our example 19.9 SEER unit into a 17.9 SEER unit and increase its electricity cost by $13 in the second season. That doesn’t sound like much, but after 5 years, the seasonal electricity cost would have increased by nearly $70. After 7 years, the high-efficiency unit would cost more to operate than a well-maintained 10.8 SEER unit!

If you have a central air conditioning unit that isn’t working as well as you think it can, contact us at Boston Standard Plumbing & Heating at (617) 288-2911. We’ll be happy to service your central air conditioning unit and return it to peak efficiency.

Boston Heating And Cooling Tax Credits Are Still Available

Homeowners haven’t totally missed the boat on last year’s home heating tax credits. Boston home heating can hit you right where it counts – in the pocketbook – so programs designed to reduce the cost of modernizing your Boston home heating system are welcome, no matter how much they cover.

This year, the generous $1,500 tax credit for certain home heating modernizations is gone with the wind. You can still claim 30% of the cost of improvements up to $500. Covered improvements include home heating, certain hot water heaters, air conditioning units and biomass stoves. One additional catch is that if you’ve claimed $500 or more in energy-efficiency tax credits between December 31, 2005 and December 31, 2010, you’re out of luck for this particular opportunity. If you’ve claimed less than $500 in the past five years, your cap will be modified, based on how much in credits you have claimed.

What does this mean for the Boston homeowner? The credit is still valuable if you want to modernize your home heating system. Aside from the tax credit, switching to a high-efficiency home heating system can reduce heating costs by as much as 50%, so even without the full value of the tax credit, updating your Boston home heating system may actually end up putting money in your pocket within the space of a few years.

Other credits for home heating and cooling include a tax credit of up to $50 for the addition of an advanced Main Air circulating fan. This device gives a boost to the blower on your furnace, and helps move heated air efficiently through your ductwork. By circulating heated air into the living space faster, the furnace actually uses less energy and runs less often.

A tax credit of up to $300 is available for Boston homeowners who want to install an air source heat pump. Heat pumps are highly efficient at exchanging heated and cooled air, and can provide as much as four times more energy (in the form of heated or cooled air) to your home than they consume. Split systems with a Heating Seasonal Performance Factor (HSPF) of at least 8.5, an Energy Efficiency Ratio (EER) of at least 12.5 or a Seasonal Energy Efficiency Ratio of at least 15 are eligible for the credit.

Thinking ahead to summer, homeowners can add central air conditioning in Boston and claim a cool $300 tax credit at the same time. Split systems that are rated with a SEER of at least 16 or an EER of at least 13 are eligible. Package systems with a SEER rating of 14 or better, or an EER of 12 or better are also eligible.

There are other credits still available for non-solar gas or electric hot water heating systems and gas, oil or propane furnaces. I’ll have more about these in a future post.