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How China's air conditioning use might affect you

How China's air conditioning use might affect you

You’ve probably never devoted a lot of thought to how your air conditioning use affects the rest of the world. So why should China’s newfound love of air conditioning bother you? The rapid adoption of climate control technologies in China and elsewhere may have a major impact on the world in the coming decades.

Air conditioning in the United States consumes more electricity than anywhere else – 616 TWh annually to be exact. In terms of the number of installed units, however, China far exceeds the US. As of 2016, China had 569 million installed AC units, compared to 374 million units in the US. Unlike the US market for AC (which is stable), the Chinese market for climate control is hot, hot, hot! As consumers in the country install more units, the demand for electricity will rise significantly. China will soon overtake the US in terms of its AC energy demands.

Globally, air conditioning consumes about 10% of all electricity produced today. Global electricity production will have to increase to meet the demand for air conditioning in emerging markets.

How you can help reduce electricity demand for air conditioning

So what does this all mean for us? In short, current methods of electricity production tend to increase atmospheric CO2 levels. To offset the growing demand for electricity, both power production and power consumption must become much more efficient.

One recommendation by the International Energy Agency is to encourage the installation of more energy-efficient air conditioning units. One reason the US currently consumes more energy on air conditioning is the large number of inefficient units still in service. Reducing the number of low-efficiency units in operation will reduce energy consumption, along with the need to produce more electricity.

Today’s high-efficiency air conditioning units offer a lot of environmental benefits. New AC units use more environmentally friendly refrigerants, take up less space, use less electricity and operate more quietly. Lower electricity usage means lower operating costs without sacrificing comfort.

Currently MassSave is offering a rebate of between $250-$500 on new central air conditioning and heat pump installations. The amount of the rebate depends upon the efficiency of the new equipment. You can qualify for a rebate of up to a $1,000 if you retire a working unit manufactured before 2007.

It’s not too late to take advantage of these exceptional incentives to install or replace your AC unit. Contact us at Boston Standard Company at (617) 288-2911 for more information on these great rebate options.

Photo Credit: Darren Poon, via Flickr

Boston Standard Plumbing Receives 2012 Angie's List Super Service Award

We’re pleased to announce that for the third year in a row, Boston Standard Plumbing & Heating has received the Angie’s List Super Service Award. The award recognizes the top five percent of all companies rated on Angie’s List during the year. Angie’s List is a member-based organization that provides consumer reviews on a wide variety of local service providers.

The awards, which were announced in late December, are given to service providers based on the number of member reviews they’ve received, the ratings given by list members, and the recipients’ ability to follow Angie’s List operational guidelines.

We’re very proud of the service we deliver at Boston Standard Plumbing & Heating, and we’d like to thank our customers for their continued support. We work hard to provide the best quality heating, cooling and plumbing products, and the outstanding service that our customers have come to know and expect.

We offer true 24-hour end-to-end emergency response services. What we mean is that when you call us – no matter what time of the day or night – the first person you talk to is a trained, certified, licensed and insured plumbing, heating and cooling professional. We don’t turn our phones over to an answering service, so we can respond immediately to your plumbing, heating and cooling emergencies.

Our fully stocked trucks are ready to roll around the clock. We keep a wide range of the most commonly needed parts in stock, so you won’t have to wait on parts to get your repair work completed. We have the staff to handle both large and small repairs, and we provide “bottom-line” quotes before we start work, so you won’t be left wondering about labor costs and time estimates.

Plumbing, heating and cooling repairs are rarely convenient and can be messy! We also take care while we work in your home, and won’t leave a mess behind. We cover your floors and items in the work area to protect them from dust, dirt and debris. We also use shoe-covers to avoid tracking dirt and debris from the work area through your home.

We offer a wide variety of the highest quality heating and cooling products, and provide certified installation services that can help you save money while keeping your home comfortable and safe. We are fully licensed and insured, so you can be confident that you’ll get the expertise you need to safely correct heating, cooling or plumbing problems in your home.

Count on Boston Standard Plumbing & Heating when you’re contemplating major system revisions, like oil-to-gas conversions, tankless water heater installations, boiler service, and central air conditioning installations or replacements. We can also provide you with a wide variety of money-saving options when your circumstances require something different. We can also help you take advantage of rebates and tax credits that are currently available for high-efficiency heating, cooling and domestic hot water systems.

When it comes to comfort and safety in your home, count on Boston Standard Plumbing & Heating, winner of the Angie’s List Super Service Award for three consecutive years! Contact us at (617) 288-2911 anytime for your plumbing, heating and cooling needs!

How Does An Air Conditioner Work?

With the temperatures nearing record heights this summer in Boston, air conditioning is on a lot of minds these days. I thought it would be valuable to take some time to explain how an air conditioner works. Knowing what your air conditioner is doing can help you take better care of it, and spot potential problems when they arise.

An air conditioner (whether it’s portable or stationary) has three major subsystems: the compressor, the condenser and the evaporator. All three systems need to be working well in order to provide cool relief from the summer heat. In addition to the major subsystems, an air conditioner has a refrigerant (also called a coolant) chemical that assists with the transfer of heat from the air inside your home to the air outside your home.

For the purpose of this blog, I’ll assume that we’re talking about a central air conditioner unit. Window units work in much the same way, except that window units have all of the subsystems in one package, so they must also handle the cool air distribution.
In a central air setup, the compressor and condenser usually remain outside the home, while the evaporator is located in or near the furnace, assuming that you have a gas/forced-air furnace. If you have a heat pump, your evaporator may be tied into or located near the air handler instead. In either case, the furnace or the air handler will perform the same function – distributing cooled air around the house.

The refrigerant flows around the air conditioning system and transfers heat to itself or to the outside air. Refrigerant is special because it can either be in gaseous form or liquid form, depending upon where it is in the cooling cycle.

The whole cooling process depends upon the unit’s ability to remove moisture from air. Hot air can carry a lot of moisture, but cool air can’t. If you remove the moisture from hot air, you get the side benefit of reducing the air’s temperature. Air conditioners (and refrigerators) remove moisture from the air by using a cold refrigerant to force the moisture in heated air to condense, and then evaporating the condensate.

At the beginning of the cycle, the refrigerant is gaseous. It is cool and under low pressure. The compressor compacts the gaseous molecules of the refrigerant together, placing them under higher pressure, which also raises the refrigerant’s temperature. The system then sends the refrigerant – which is now hot and under a lot of pressure – off to the condenser.

At this point, you have two things you don’t want: heat and gas. You really want the refrigerant to be cool and liquid. The condenser’s job is to get rid of the heat in the refrigerant while converting it to a liquid state. Because you’re working with twho things you don’t want, the condenser does it’s job outside!

The condenser is covered with many thin, metal fins, which help the heat dissipate from the refrigerant. A fan blows the heated air across the condenser coils. The fins increase the surface area of the condenser and give the heat more opportunity to get rid of heat. The refrigerant lets go of its heat and converts to a cool, high-pressure liquid. This cooled liquid refrigerant is sent to the evaporator through a very small-diameter hole, which helps it retain its liquid state.

The high-pressure liquid travels through the narrow channel to the evaporator. An expansion valve regulates the refrigerant’s trip to the evaporator. Once the refrigerant arrives, the pressure drops and it converts back to a gas. When a liquid converts to a gas, it absorbs heat. Some compounds are better at doing this than others, and refrigerants happen to be very good at absorbing heat while they convert back to their gaseous states. They also readily enter their gaseous states at relatively low temperatures.

As the hot air from the house hits the evaporator, the refrigerant inside begins to absorb heat and collect moisture out of the air. Like the condenser, the evaporator is also covered with thin metal fins, and uses a fan to help with the transfer of freshly cooled air from the system to the living space.

The refrigerant – once again in its gaseous, low-pressure state – is sent back to the compressor to start the process over again.

If you’re having trouble with your air conditioner, give us a call at Boston Standard Plumbing & Heating at (617) 288-2911. We work with all major brands of central air conditioners and can help you keep your system operating efficiently!
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Rising Heat Is A Good Reminder To Change Your AC Filter

With the temperatures on the rise, and summer finally here in Boston, air conditioner maintenance is on our minds. Now is a good time to change the air filter on your central air conditioning unit! Depending upon the kind of central air system you have, your air filter will be located either in your furnace or in your system’s air handler.

For systems that use the furnace as the air handler, replace the filter with a fresh one every month. Do this regularly to help keep your system operating cleanly and efficiently. In addition to reducing efficiency, clogged filters can trap (and eventually redistribute) a lot of nasty things like mold, pollen, pet dander, dust and other allergens that will make you less comfortable in your home.

If you need a reminder to change your air filter, try sending yourself an email reminder from your electronic calendar every month. Google and Outlook will both do this, and it’s an easy, free way to make sure you remember to change your AC filters!

If your system suddenly stops operating, check the breaker panel or fuse associated with your air conditioning system. Breakers sometimes trip because they’re weak. Resetting them should put your system back in working order. If the breaker trips regularly, however, it could be a sign that your compressor motor is drawing too much current when it starts up.

Motors do tend to draw a lot of current at startup; this is normal and all motors do this. Almost immediately after starting, however, the current flow to the motor should stabilize and the circuit should operate normally and safely. Sometimes, an aging compressor can draw too much power – a sign that something’s wrong with your system. Also, your system could be outfitted with a breaker that won’t tolerate a huge, brief current draw.

If your AC breaker trips consistently, give us a call at (617) 288-2911, and we’ll observe your system to diagnose and correct the problem.

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Cleaning Your Air Conditioner's Evaporator Coil

Last week, I covered the basics of cleaning your air conditioner’s condenser unit and performing some basic maintenance. This week, I will cover the inside maintenance you’ll want to perform to clean your air conditioner’s condenser unit.

The inside maintenance on your air conditioner is just as important as the outside maintenance. Keeping your evaporator clean and free of corrosion will ensure that your unit operates efficiently year round. It will also allow you to spot potential problems before they lead to a major repair.

The inside unit is the evaporator, and it will be located near your furnace (if you have a furnace) or in your air handler if you have a heat pump. For this post, I’m going to assume that the evaporator sits on/near a furnace, but the steps for cleaning the evaporator are the same if you have an air handler instead.

Access your evaporator coil by opening the metal case that encloses it. The coil is often designed as an “A-frame” device, which means it has two panels that appear to lean toward each other (like the letter “A”). The evaporator panels will have thin metal fins on the outside and a series of copper tubes on the ends of the unit. The entire set-up will rest on a plastic (or metal) frame of channels that catch water and shunt it to the drain. The bottom of the evaporator is open to allow air to circulate from the blower motor of your furnace. Check the plastic frame for cracks, or if your unit has metal channels, check them for corrosion or rust. If a channel is cracked or rusted through, you’ll need to replace it to avoid damaging the rest of the furnace.

The evaporator’s job is to remove water from the air. On a very hot, humid day, your evaporator might eliminate several gallons of water from the air in your home, so it’s important to keep the condensate drain free-flowing at all times. Even though you’re condensing out “clean” water, biological matter can accumulate in the drain tube for your system and cause a backup. If your air conditioner is pulling gallons of water out of your home’s air and the tube that leads to your floor drain is clogged, you’ll find very quickly that you have drain problem AND a big mess to clean up!

Before you do anything on the evaporator, make sure the condensate drain is clear and free-flowing by running a little water in the catch basins at the bottom of your evaporator unit. If the water you add doesn’t flow freely to the drain, you can use a little Bio-Clean to clear out any accumulated biological debris in the drain. You can also use a solution of bleach and water to clear out any biologically active organisms in the drain.

Once you know the drain is fully open, examine the evaporator coils. If they’ve never been cleaned, or haven’t been cleaned recently, they’ll be coated with dust and other “inside” debris, like pet hair and cobwebs. You’ll need to make a decision about how well you can manually clean debris from the unit using the access you have. If you can’t get the fins clean without damaging them or the debris is crusted on, you may want to have a professional perform the inside maintenance. A badly clogged evaporator may need to be removed for cleaning, and that’s outside the realm of a do-it-yourself task.

You can find spray-on condenser coil cleaner at your hardware store or a home-improvement store. Usually, these cleaners are foaming and will break down debris and any greenish deposits that accumulate on the copper without needing a rinse. Spray the cleaner on the copper tubing and on the fins of the evaporator. The foaming cleaner will clean debris, return to a liquid state, and drain into the condenser pan on its own. You can use this when the air conditioner is running to get a little “rinse” from the water the evaporator is removing from the air. The cleaner takes just a few minutes to work, and you should be good to go, once you close the unit back up.

Change the air filter as long as you have the unit open. Just as in the heating season, you’ll want to change your furnace filter monthly to ensure that your system isn’t working harder than it has to. If you have questions about cleaning your evaporator unit, or you would like professional assistance, contact us at Boston Standard Plumbing & Heating at (617) 288-2911 to schedule an appointment. Also, you can “like” Boston Standard Plumbing on Facebook anytime!

Regular Air Conditioner Maintenance Is A Must

Spring has come early this year, and while the temperature change has been nice (and welcome), it’s a good reminder that the 2012 cooling season is nearly upon us. If you have an air conditioner, you’ll need to do some annual air conditioner maintenance to ensure that your AC unit works well, efficiently and remains trouble-free.

Don’t skip this step, even if it seems complicated. That’s because a central air conditioning unit can lose 5%-10% of its rated efficiency each year that regular maintenance isn’t performed. Within a couple of years, the high-efficiency air conditioner you paid a premium will provide lower performance than a well-maintained moderately efficient air conditioner!

Keeping your system clean is one of the primary ways in which you preserve the unit’s efficiency. Cleaning the unit means cleaning the condenser, which is outside, and the evaporator coils, which are inside your home. Neither of these tasks are difficult, and they’re certainly within reach of the DIY’er, but they do take a little time and effort, and you’ll need to have a good understanding of your heating and cooling equipment.

The outside condenser unit is covered with a metal case, which can be removed easily for cleaning. Before you remove the cover, you’ll want to cut the electricity to the unit at the circuit breaker. Once the unit is safely powered down, you’ll want to make sure that all organic debris (i.e., dead leaves, sticks, old grass clippings, nests, seeds, etc.) that may have found their way into the condenser unit are cleared away. This is also a good time to remove grass, weeds and other growth from the condenser unit to prevent this kind of material from entering the condenser unit later this season.

This is also a good place to point out that you may need to clean your condenser several times during the summer season. If you live near cottonwood trees, for example, they “seed” in June. Their cottony seeds float through the air like snow and will get sucked into your condenser. Any debris – including lawn clippings, petals from flowering trees, seeds and seed coats from landscaping – can clog your condenser and reduce its efficiency. Check the condenser regularly during the cooling season for debris. This will help keep your unit working at peak efficiency and can prevent premature failure for some components.

This unit is built for outdoor use, so you can use a hose and running water to clear out the condenser unit and the coils. Take special care to avoid damaging the “fins” or any delicate metal tubing you see in this unit. Make sure the drip pan (at the very bottom of the unit) is free from debris that can trap moisture and promote rust and other corrosion.

After you have the condenser unit clean, you can oil the unit if your unit requires it. Many units are self-lubricating or are sealed, so no additional lubrication is required. If your fan motor has oil ports, however, you’ll want to ensure that your unit is lubricated at least seasonally. You can do this by adding about 5 drops of oil to the oil port. Don’t use penetrating oil and don’t use an “all-purpose” oil. Instead, use the oil recommended by your manufacturer, or you can find lubricating oil for electric motors at your local hardware store.

Again, if the compressor motor requires lubrication, add a few drops through the oil port. (Check your owner’s manual if you’re not sure where the port is located, or if you need to lubricate your compressor motor.) Do not over-lubricate your unit.

If your compressor is belt-driven, inspect the belt for wear, glazing, cracking and signs of overheating. Also check under the motor for evidence of oil leaks. (Old oil will be dark and may pool under the compressor motor or at a connection point, or you may find evidence of oil spray buildup on the motor case.)

If you find evidence of a leak, chances are good that you’ll need to replace the motor. Unless you find a connection that is obviously loose, don’t attempt to tighten connections where you suspect an oil leak. Over-tightening can cause more damage to your unit and isn’t likely to solve your problem.

Check for coolant problems to the extent you are able. To do this, you’ll need to power on the unit. Adjust the inside thermostat so that the unit runs for about 5-10 minutes. Carefully move the insulation on the copper pipe that leads to the inside unit to expose the metal. The metal pipe should be cool (but not super-cold) to the touch. If the temperature of this pipe isn’t cool, call a professional to check the coolant level in your unit. Your unit may need to be recharged.

One more note on compressors: they’re not designed to work in cold temperatures, so reserve your unit maintenance until the outside temperature is in the 60°F-65°F degree range.

After you’ve checked for evidence of proper cooling, shut the unit back down and return the cover to its operating position.

In my next post, I’ll cover the inside work you’ll need to complete to make sure your air conditioning unit is ready for the cooling season.

If you have questions about air conditioner maintenance, or would like the pros at Boston Standard Plumbing & Heating to perform your air conditioning maintenance for you, please give us a call at (617) 288-2911 anytime and we’ll schedule a visit. Don’t forget to like us Boston Standard Plumbing on Facebook!

Keeping Your Cool This Summer In Boston

Spring seems to have made an early appearance, so there’s no better time to get your annual air conditioner maintenance done. In the next few posts, I’ll be concentrating on air conditioning, and what you’ll want to do to be sure you can avoid an expensive air conditioner repair in Boston this summer.

As far as operation goes, one of the best, easiest and nicest things you can do for your air conditioner is change the filter regularly. Use pleated filters and change them no less often than 90 days. If you have pets in your home, change the filter more frequently. This will help protect the unit’s secondary heat exchanger and the evaporator coil, and it will keep dirt and other debris out of the blower wheel, which can cause your unit to malfunction.

Can’t find your AC filter? Check your furnace! (It’s usually the same filter you change during the heating season.) Some units have a filter located in a ceiling return air grille, but if you have central air conditioning that uses your furnace ductwork, your filter’s most likely in your furnace.

Changing the filter regularly has some other benefits, as well. Pushing air through a dirty, or clogged filter can decrease the efficiency of your air conditioner. It can also introduce dirt into other moving parts of the air conditioner, reducing their effectiveness and increasing the amount of electricity your air conditioner consumes.

Dirty air filters can also be a source of odor and airborne allergens in your home. Filters will collect contaminants like mold, mold spores, pollen and other irritants. If you inspect your air conditioner filter and notice that it has mold growth or has a funny smell, change it immediately.

Keep some clean filters on hand so you can perform a quick change whenever you need to. If you’re not certain how often to change the filter, inspect the filter periodically to note its condition. When you see a lot of dirt or debris collecting on the filter, change it.
If you’re thinking about skipping the filter altogether, don’t. Running your system without a filter will cause the evaporator coil the air handler to clog. This will lead to icing on the air conditioner – something you definitely don’t want.

If you have questions about your air conditioner, or would like to schedule pre-season maintenance, give us a call at Boston Standard Plumbing & Heating at (617) 288-2911 anytime. We’ll be happy to schedule a seasonal maintenance check and show you how to maintain your system during the summer.

Don’t forget to like Boston Standard Plumbing on Facebook, and if you make a platelet donation to the Kraft Family Blood Donor Center during the month of April, we’ll take $50 off of any Boston Standard Plumbing & Heating purchase or service call worth $100 or more!

Does Changing Your Furnace Filter Really Matter?

Your forced-air furnace has a filter that helps catch dust and debris. Ultimately, the filter prevents this material from being distributed through the ductwork. Most forced-air furnaces have disposable filters, although you can buy cleanable filters you can re-use. Furnace manufacturers recommend that the filter be cleaned or changed monthly for best performance. For homeowners in Boston, furnace maintenance is key to keeping your furnace working properly.

But what’s the harm in not changing your filter? Aside from the fact that the filter will become clogged with dust and debris, your furnace will also have to work harder to get air through the clogged filter. Your hard-working, high-efficiency furnace will become less efficient (which costs you more money) and over time, you can actually reduce the lifespan of important furnace components.

Furnace filters are sized to fit the furnace you use, so the first rule of thumb is to use the correct size filter for your furnace. You can usually purchase disposable furnace filters at your local home improvement store. Check your owner’s manual to determine the correct filter size for your unit, and buy enough filters each fall to get you through the heating season.

Changing the furnace filter (usually once per month) isn’t hard, but it is possible to install the filter backwards. Normally, filters are marked to indicate which side of the filter should face up/out, so be sure you know which direction you’re supposed to install the filter.

Don’t attempt to clean or re-use disposable filters. They aren’t meant to be cleaned, and there’s really no good way to get the accumulated dust and debris out of the filter. In addition, trying to dislodge the dust and debris mechanically can actually deposit the particles right back into the air. When you’re done with a filter, carefully place the used filter in a trash bag and send it on its way.

At the end of the heating season, place a new filter into your furnace. That way, when heating season starts up in the fall, your filter will be good to go. The same trick applies to your air conditioner. Change the filter at the end of the season so a dirty filter isn’t waiting for you the next time you want to use the unit.

If you just can’t remember to change your filter, write it on your calendar or send yourself a monthly email reminder. Google Calendar is a great (and free) way to remind yourself of this simple-yet-important task!

If you have any questions about your heating and cooling systems, or need help finding or changing your filter, contact Boston Standard Plumbing & Heating at (617) 288-2911 anytime. We can schedule an inspection right away and help you get your heating (and cooling) filter maintenance routine set up.
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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.

Air Conditioning and Energy Efficiency

In Boston, air conditioning is needed only for a few months during the year, so homeowners may wonder whether central air conditioning is really needed? Will window units suffice? How much will central air conditioning cost to install, maintain and operate? One big part of the answer is efficiency. Highly efficient central air conditioners may be less costly to operate than fans or other cooling options.

Air conditioners come with energy efficiency ratings that can help you determine how much your air conditioning system will cost. Generally, highly efficient air conditioners are more expensive to purchase but cost less to operate. The seasonal energy efficiency rating (SEER) of an air conditioning unit tells you what you can expect from your air conditioner, and can also help you compare the effective cost of different models over time.

One important measure of an air conditioning unit is its BTU output. A BTU is a British thermal unit, and it is a measure of the air conditioner’s cooling output. Small, room-sized air conditioners have BTU ratings in the neighborhood of about 5,000. Larger room units might have a BTU rating of 8,000-15,000. To compare, a central air conditioning unit might have a BTU rating of 25,000 – 60,000.

The ratings are important because they provide an indication of the square footage a single unit can cool. They can also help you figure out which air conditioners are powerful enough to cool your home, assess different models, and calculate or compare the operational costs.

Generally, efficiency is a measure of what you get out versus what you put in. The SEER, therefore, is a comparison of how many BTU you get out of your air conditioner compared to the electricity it consumes, measured in Watt-hours (W-h). The unit of measure for a SEER is BTU/W-h. The higher the SEER the more efficient the air conditioner is, and the less it costs to operate.

If you have a 5,000 BTU window air conditioner with a SEER of 10.8, your air conditioner will use about 465 watts/hour or .465kW/hr. (5,000/10.8 = 463W or .463kW). If NSTAR charges a summer rate of $0.05/kW hour, your operating cost for the unit will be less than $0.025 per hour. If you operate the unit 8 hours per day, the cost will be about $0.19 per day. An air condition that size will cool off a bedroom and will set you back about $21 for the entire summer. If you rent, don’t spend a lot of time at home, or don’t mind the heat but just want to sleep comfortably at night, a window air conditioner will probably meet your needs nicely, even though it isn’t as efficient as some other cooling options.

Next week, I’ll compare the operating costs of low-efficiency and high efficiency central air conditioners, and you’ll see why high-efficiency central air conditioning systems are really the way to go if you want to cool the whole house. In the mean time, contact Boston Standard Plumbing & Heating anytime for all of your plumbing, heating and cooling needs. We can be reached at (617) 288-2911 anytime!