Resource Library / So You’re Considering an Air Conditioning Replacement
So You’re Considering an Air Conditioning Replacement
- Posted: Aug 25, 2009
This article is intended to assist consumers with the very difficult decision of choosing the right comfort system for their home and family. Every application is a little different, just as every family has slightly different needs, wants and challenges. Some families have multiple generations living in the same home, while others have a home office, some have immune-compromised or allergenic family members, and still others are out of the home for long period of time. Every situation is unique and the heating, ventilation, and air conditioning industry has a myriad number of options to address every situation that life can throw at it. In this document, you will learn about industry jargon, common terms, available rebates, options you can choose, and how to read between the lines in your estimates. To us, an educated customer is the best kind, as you won’t feel vulnerable, overwhelmed, or muscled into a decision about an appliance you don’t understand. Once you have all of your reading out of the way you’ll be able to make a decision you feel comfortable about with a company you feel great about!
Two-thirds of all homes in the United States have air conditioners. Air conditioners use about 5% of all the electricity produced in the United States, at a cost of over $11 billion to homeowners. As a result,roughly 100 million tons of carbon dioxide are released into the air each year—an average of about two tons for each home with an air conditioner. Switching to high-efficiency air conditioners and taking other actions to keep your home cool could reduce this energy use by 20%–50%.
System Sizing
Heat Load Calculation or Manual J—a technique that evaluates your home’s volume, construction methods and materials, window area, and arrives at the accurate heat nfiltration (or heat gain) in British thermal units so that an appropriately sized unit can be proposed for the replacement. Older space conditioning systems (more than 10 years old) are often unreliable and much less efficient than a modern system. When it's time for a new replacement, choosing one of the correct size (heating and/or cooling output) is critical to getting the best efficiency, comfort, and lowest maintenance and operating costs over the life of the new system. Some national surveys have determined that well over half of all HVAC contractors do not size heating and cooling systems correctly.
The most common sizing mistake is in oversizing. This not only makes the new system more expensive to install, but also forces it to operate inefficiently, break down more often, and cost more to operate. Oversized heating equipment also often creates uncomfortable and large temperature swings in the house. Oversized air conditioners (and heat pumps) do not run long enough to dehumidify the air, which results in the "clammy" feeling and unhealthy mold growth in many air-conditioned houses (see dehumidifying heat pipes as one solution to this problem).
Incorrect Sizing Methods
It is the installer/contractor's job to perform the correct sizing calculation for the building. However, many installers only check the "nameplate" (the label on the unit that has the Btu per hour output among other things) of the existing system and sell you one just like it, or even worse, one that's larger. This is a not a correct sizing method and not in your best interests! Other methods include simple "rules of thumb" based on the size of your home or using a chart that accounts for a variety of factors. While these methods might provide a first estimate, they should not be used to size your system.
Why Most Older Systems are Oversized
Before the era of tightly constructed homes, it was not uncommon to install furnaces and air conditioners that had two to four times the necessary capacity. Since many people have added new windows, caulking, weather-stripping, and insulation to their homes, going by the nameplate is likely to result in an oversized system. Making improvements such as these to reduce heat loss in the winter and heat gain in the summer should allow you to install a smaller system while still being comfortable, as
well as saving large amounts of energy.
Manual J and Manual D: The Correct Way to Size a System
Correct system sizing requires considering many factors other than simply reading the nameplate of the existing unit. Key factors for correctly sizing a heating and cooling system include the following:
Homeowners should insist that contractors use a correct sizing calculation before signing a contract. This service is often offered at little or no cost to homeowners by gas and electric utilities, major heating equipment manufacturers, and conscientious heating and air conditioning contractors. Manual J, "Residential Load Calculation," published by the Air Conditioning Contractors of America (ACCA), is the recommended method for use in the United States. There are also many user-friendly computer
software packages or worksheets that can simplify the calculation procedure. You should make sure that the procedure used by the contractor follows Manual J.
What is a SEER Anyway?
SEER—Seasonal Energy Efficiency Ratio—is a term used in thermodynamics that reflects how efficient the unit is. The higher the SEER rating of a unit, the more energy efficient it is. The SEER rating is the btu (BTU—British Thermal Units. Air conditioners are sized by tonnage. A ton of air conditioning produces 12,000 btus of cooling capacity. A five-ton unit would provide 60,000 btus of cooling.) of cooling output during a typical cooling-season divided by the total electric energy input in watt-hours
during the same period.
SEER rating more accurately reflects overall system efficiency on a seasonal basis and EER reflects the system’s energy efficiency at peak day operations. Both ratings are important when choosing products. As of January 2006, all residential air conditioners sold in the United States must have a SEER of at least 13. ENERGY STAR qualified Central Air Conditioners must have a SEER of at least 14. Today, it is rare to see systems rated below SEER 9 in the United States because aging, existing units are being replaced with new, higher efficiency units. The United States now requires that residential systems manufactured after 2005 have a minimum SEER rating of 13, although window units are exempt from this law so their SEERs are still around 10. Substantial energy savings can be obtained from more efficient systems. For example by upgrading from SEER 9 to SEER 13, the power consumption is reduced by 30% (equal to 1 - 9/13). It is claimed that this can result in an energy savings valued at up to US$300 per year depending on the usage rate and the cost of electricity.
Maintenance should be performed regularly to keep their efficiencies as high as possible.
But when either replacing equipment, or specifying new installations, a variety of SEERs are available. For most applications, the minimum or near-minimum SEER units are most cost effective, but the longer the cooling seasons, the higher the electricity costs, and the longer the purchasers will own the systems, incrementally higher SEER units are justified. Residential split-system ACs of SEER 20 or more are now available, but at substantial cost premiums over the standard SEER 13 units.
Calculating the annual cost of power for an air conditioner.
Air conditioner sizes are often given as "tons" of cooling where 1 ton of cooling is defined as being equivalent to 12,000 BTU/h. The annual cost of electric power consumed by a 72,000 BTU/h (6 ton) air conditioning unit operating for 1000 hours per year with a SEER rating of 10 and a power cost of 12¢ per kilowatt-hour (kW·h) may be calculated as follows:
(72,000 BTU/h) × (1000 h) × (12¢/kW·h) ÷ (10 BTU/W·h) ÷ (1000 W/kW) = $864 annual cost
If you’re not into equations, we’ve decided to make it a little simpler to follow. The next page contains a spreadsheet that will show you the typical energy use for a home in West Florida, with a 3 ton, 10 SEER unit, that has the indoor temperature set at 78 degrees in the summer. At your appointment with us, we can load your actual size unit into the spreadsheet, and give you a good idea of what to expect when it comes to your actual power savings.
SEER Savings Calculation
Heat Pump Systems: Do I need one? Do I want one?
For climates with moderate heating and cooling needs, like west central Florida, heat pumps offer an energy-efficient alternative to furnaces and air conditioners. Like your refrigerator, heat pumps use electricity to move heat from a cool space into a warm, making the cool space cooler and the warm space warmer. During the heating season, heat pumps move heat from the cool outdoors into your warm house; during the cooling season, heat pumps move heat from your cool house into the warm outdoors. Because they move heat rather than generate heat, heat pumps can provide up to 4 times the amount of energy they consume.
The most common type of heat pump is the air-source heat pump, which transfers heat between your house and the outside air. If you heat with electricity, a heat pump can trim the amount of electricity you use for heating by as much as 30%–40%. High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months. However, the efficiency of most air-source heat pumps as a heat source drops dramatically at
low temperatures, generally making them unsuitable for cold climates, although there are systems that can overcome that problem.
Heat Pump Operations
Proper operation of your heat pump will save energy. Continuous indoor fan operation can degrade heat pump performance and increase the humidity level in your home. Operate the system on the "auto" fan setting on the thermostat.
Like all heating and cooling systems, proper maintenance is key to efficient operation. The difference between the energy consumption of a well-maintained heat pump and a severely neglected one ranges from 10%–25%.
Clean or change filters once a month or as needed, and maintain the system according to manufacturer's instructions. Dirty filters, coils, and fans reduce airflow through the system. Reduced airflow decreases system performance and can damage your system's compressor. Clean outdoor coils whenever they appear dirty; occasionally, turn off power to the fan and clean it; remove vegetation and clutter from around the outdoor unit. Clean the supply and return registers within your home, and straighten their fins if bent.
You should also have a professional technician service your heat pump at least twice every year.
Advanced Technology
A number of relatively new innovations are improving the performance of heat pumps.
Unlike standard compressors that can only operate at full capacity, two-speed compressors allow heat pumps to operate close to the heating or cooling capacity that is eeded at any particular moment. This saves large amounts of electrical energy and reduces compressor wear. Two-speed heat pumps also work well with zone control systems. Zone control systems, often found in larger homes or homes with multiple living arrangements, use automatic dampers to allow the heat pump to keep different rooms at different temperatures.
Some models of heat pumps are equipped with variable-speed or dual-speed motors on their indoor fans (blowers), outdoor fans, or both. The variable-speed controls for these fans attempt to keep the air moving at a comfortable velocity, minimizing cool drafts and maximizing electrical savings. It also minimizes the noise from the blower running at full speed, making these systems some of the quietest available on the market today. As a bonus, these systems run on low speed nearly 90 percent of the
time, which maximizes the humidity removal and increases both the comfort in the home and indoor air quality.
Another advance in heat pump technology is the scroll compressor, which consists of two spiral-shaped scrolls. One remains stationary, while the other orbits around it, compressing the refrigerant by forcing it into increasingly smaller areas. Compared to the typical piston compressors, scroll compressors have a longer operating life and are quieter. According to some reports, heat pumps with scroll compressors provide 10°–15°F (5.6°–8.3°C) warmer air when in the heating mode, compared to existing heat pumps with piston compressors.
Air Conditioning 101
Air conditioners employ the same operating principles and basic components as your home refrigerator. Refrigerators use energy (usually electricity) to transfer heat from the cool interior of the refrigerator to the relatively warm surroundings of your home; likewise, an air conditioner uses energy to transfer heat from the interior of your home to the relatively warm outside environment.
An air conditioner cools your home with a cold indoor coil called the evaporator. The condenser, a hot outdoor coil, releases the collected heat outside. The evaporator and condenser coils are serpentine tubing surrounded by aluminum fins. This tubing is usually made of copper.
A pump, called the compressor, moves a heat transfer fluid (or refrigerant) between the evaporator and the condenser. The pump forces the refrigerant through the circuit of tubing and fins in the coils.
The liquid refrigerant evaporates in the indoor evaporator coil, pulling heat out of indoor air and thereby cooling your home. The hot refrigerant gas is pumped outdoors into the condenser where it reverts back to a liquid, giving up its heat to the outside air flowing over the condenser's metal tubing and fins.
Ask about Proper Installation of your new equipment
Replacing your old heating and cooling equipment with new, energy-efficient models is a great start. But to make sure that you get the best performance, the new equipment must be properly installed. In fact, improper installation can reduce system efficiency by up to 30 percent — costing you more on your utility bills and possibly shortening the equipment's life.
Finding Qualified Equipment:
The Consortium for Energy Efficiency (CEE) and the Air-Conditioning and Refrigeration Institute (ARI) have developed an online database which can be used to find qualifying ENERGY STAR equipment. All equipment listed in this online database meets the specification requirements for ENERGY STAR. This online database is solely maintained and operated by CEE and ARI. Your contractor should furnish you with the ARI certificate for your system to ensure the efficiency of the system is as promised. You can check it yourself at www.ari.org.
Available Rebates, Tax Credits, and Incentives
Rebates and incentives are available, but they are dependent on a variety of qualification factors. If your power is supplied by TECO or Progress Energy, rebates are available if you opt for a heat pump system greater than 15 SEER. The rebate amount varies depending on the type of unit you currently have, the efficiency of the unit you install, and the inspection performed by the power company after the installation. TECO rebates are discounted off of the price of the unit; Progress Energy rebates are
delivered in the form of a credit on your power bill.
Manufacturers often offer cash incentives. Please check with your representative for current rebates.
Tax Credits for Consumers:
Home Improvements
Tax credits are now available for home improvements:
Definitions of ratings:
Heating Seasonal Performance Factor (HSPF):
Can’t I Just Replace a Piece of the Unit?
Most homes today in West Central Florida use split systems, while most mobile or manufactured homes use a “packaged” system. Mini-splits are also available. Split systems are made of up a condensing unit, installed outside the home, an air handling unit, installed inside the home. Packaged units, on the other hand, are contained in one unit installed outside the home. Both provide the same conditioned air, but with different levels of sound and efficiency.
After March 1, 2009, permits to install units won’t be issued in most counties in Florida for equipment that doesn’t meet the federally mandated minimum of 13 SEER. That means if you have a newer “piece” of equipment that CAN be matched with another piece to produce the 13 SEER, you’re covered. If the piece is 3 years of age or older, it might be difficult to find a piece. Quality contractors don’t recommend “piecemealing” systems together, as it isn’t in the consumer’s best interest. With the warranties and
efficiencies available today, it is best to replace the entire system.
Permit!? Did you say PERMIT?!
You bet. It is for your protection! The building codes are in place to protect homeowners and ensure their safety. If anyone says that permits drive up the cost of unit, they’re right, in a way. It keeps people from cutting corners that compromise the equipment’s longevity and your safety!
Here’s the process:
1. A licensed contractor applies to the county for a replacement unit permit.
2. Then, they post the permit at your home and install the unit, bringing everything surrounding the unit into compliance with the current codes.
3. After installation is complete, an “inspection” is called in and a county inspector visits the home, checking for compliance with the code.
4. The inspection either passes or fails. If it fails, a “tag” is left, listing the infractions.
Don’t use anyone who works without a permit. It puts you at risk!
A Word About Brands
In this day and age, most equipment is reliable. In fact, the most brands use Copeland Scroll compressors! Brands are really a matter of preference from the consumer’s standpoint. Look for the factory parts warranty, which should be 10 years and don’t settle for less. Lifetime compressor warranties are a nice, safe bonus. What really matter is the installation. Any brand works well when installed properly, and every brand will fail when installed without attention to details like copper sizing, static pressure in ductwork, and proper seals and sizing for your application. The labor warranty lets you determine how long the contractor is responsible for the repair bills, and with a purchase of this magnitude, it ought to be at least 10 years. If a compressor fails after the installing contractor’s labor guarantee lapses, it could mean upwards of $600 in bills for you.
Indoor Air Quality
Lots of people suffer from allergies and asthma. Billions of dollars are spent annually on room air cleaners and filters to improve the quality of their indoor air, which often (according to the American Lung Association) contains more irritants than outdoor air. Americans spend 80 percent of their time indoors, so making the air we breathe the cleanest it can be is certainly a priority. That priority escalates when someone in the family is suffering. Whether it is a child with asthma, an adult suffering from allergies and migraines, or someone with a compromised respiratory system, your air conditioner can help! That’s right: your air conditioner can be part of the solution.
Three Steps to Better Indoor Air Quality
In truth, there are three steps to improving the air.
1. Remove source pollutants. No smoking, etc.
2. Filter out the pollutants.
3. Dilute, or add fresh outside add to pressurize the home and minimize the contaminants.
Sounds easy, right? When you consider the hundreds of types of filters out there, and then add to that hundreds more indoor air quality devices like UV lights, then mix it all up with your specific problems and contaminants, indoor air can get downright confusing. There is a great way to sort it out.
One great way is to address the humidity in your home. The optimal humidity for human life is 50 percent. That level, however, is not optimal for a dust mite! At that humidity level, dust mites can’t thrive or reproduce, molds can’t form and spore, and lungs breathe easy. Easy solution, right? All it takes is a correctly sized air conditioning system and a system designed for optimal humidity removal. There are many systems that have thermostats that can control both humidity and temperature. Be sure to ask for options that perform in this way if allergies or asthma is a concern for your family. You can’t afford not to! Make sure the thermostat is able to be set to detect and respond to humidity calls as well as temperature calls, and ensure the operation of the unit by requiring a variable speed air handler (a two-speed compressor is optimal) be pair with that thermostat.
Don’t buy any filtration system until you know precisely what’s in your air. Some homes have an abundance of particulate, while other have issues with volatile organic compounds (VOCs); some homes have both. People spend lots of money that they don’t have to by trying to filter out the wrong things. Using an analytical device call the AirAdvice, you can determine exactly what’s in your air, where your humidity levels are, and pinpoint exactly which solution is appropriate for your problem without spending more than you need and getting an extremely effective solution. (Bayonet Plumbing & AC will be glad to perform the AirAdvice test for you.)
Humidity percentage
Types of Filters Available
The Main Types of Filters are Media Filters, Electronic Air Cleaners, Photocatalytic Air Cleaners, HEPA filtration systems. Each will be explained in brief below.
Media Filters: these are whole house filters installed on the return side of your air handler or furnace. They provide the added benefit of keeping your coil clean, which helps keep your system running efficiently. If you have multiple returns in your home, all of the filters can be removed when this one is installed (and should be to prevent problems). All media filters are not created equal! They are rated with a MERV rating system. ($$)
MERV ratings are used to rate the ability of an air conditioning filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminats pass through the filter.
MERV ratings range from 1 - 16 and measurements are in microns. Some of the common particles related to MERV ratings are pet dander, insecticide dust, smog, dust, viruses, wood, tobacco smoke, spores, bacteria and pollen.
Some of the most common filters found in residential use only have a are typically disposable panel type filters and do not do a good job of filtering the air because they will
not stop particles smaller than 10 microns. Merv 5 to 8 rated filters are a better choice and are more commonly found in commercial applications. These filters will collect particles as small as 3 microns and are a good choice for home owners also.
Filters with a merv rating of 9 to 12 are used in commercial and industrial appliactions will stop particles in the 1 to 3 micron range. These filters are a great choice for home owners who want the best dust control possible. When using filters with Merv 9 ratings and above it is important to clean or replace them when recommended by the manufacturer because they will have a negative effect on air flow when they become dirty. This can lead to performance problems and decreased operating efficiency.
The most efficient filters have merv ratings of 13 to 16 and will stop particles as small as .3 microns. These filters are used in hospitals and other super clean environments.
Most media filters need replacing annually, but some will need replacement every 6 months dependent on living conditions.
HEPA Filters: Before getting into details about hepa air filters it is important to first answer a commonly asked question regarding the word HEPA. What does hepa stand for? HEPA is an acronym which stands for High Efficiency Particulate Arrestance. To qualify as a HEPA filter, the filter has to capture a minimum of 99.97% of all particles 0.3 microns in diameter. That is about 300 times smaller than the diameter of a human hair and smaller than we can see.
Hepa air filters are among the most efficient air conditioner filters available. At over 99 percent efficient, a hepa air filter will remove almost all allergens from the air that passes through your HVAC equipment. Hepa air filters remove dust mites, pet dander, pollen, mold spores and other household allergens.
Hepa air filters are commonly used in environments where very clean air is a must, such as clean rooms, hospital wards, surgical rooms and other places where maximum dust removal is very important. Hepa filters are also used in many other applications such as very efficient hepa vacuum cleaners and HEPA air cleaners. They do, however, require strict maintenance to maintain performance. They are typically expensive to install and do not provide any protection for your coil.
Electronic Air Cleaners: these units require a small amount of electricity to operate and produce a small amount of ozone as a by-product. They are attached to your indoor unit (air handler or furnace) and they work by adding an ionic charge to airborne particles and then attracting them to collector plates. They are slightly more expensive to purchase and install, but do not require filter changes, as the electronic cells are washable. As with all electronics, the electronic cells and ionizing wires can wear out or break, so be careful when choosing this option. ($$$)
Filters with Photocatalytic Oxidation: in simplest terms, this is the best of all solutions, providing a broad spectrum solution without ozone. A great example is Lennox’s PureAir. It uses a MERV 16 media filter in conjunction with a bank of UVa lights with titanium-dioxide coated plates that provide a photocatalytic effect on air passing through the plates. In layman’s terms, this filter removes all smells, odors, and VOCs from the airstream. In scientific terms, it hydrolyzes bioaerosols. Either way, when paired with a humidity-controlling system, this is the penultimate option.
This article was composed for Bayonet Plumbing, Heating, and Air Conditioning Inc’s customers by Bayonet sales manager Kris Blankenship. Please do not reproduce without permission, but please feel free to bombard us with your questions. We hope you feel a little more prepared to evaluate and state your needs and more comfortable with the ins and outs of an AC system.
To download a PDF of this article, click here.
- Posted: Aug 25, 2009
This article is intended to assist consumers with the very difficult decision of choosing the right comfort system for their home and family. Every application is a little different, just as every family has slightly different needs, wants and challenges. Some families have multiple generations living in the same home, while others have a home office, some have immune-compromised or allergenic family members, and still others are out of the home for long period of time. Every situation is unique and the heating, ventilation, and air conditioning industry has a myriad number of options to address every situation that life can throw at it. In this document, you will learn about industry jargon, common terms, available rebates, options you can choose, and how to read between the lines in your estimates. To us, an educated customer is the best kind, as you won’t feel vulnerable, overwhelmed, or muscled into a decision about an appliance you don’t understand. Once you have all of your reading out of the way you’ll be able to make a decision you feel comfortable about with a company you feel great about!
Two-thirds of all homes in the United States have air conditioners. Air conditioners use about 5% of all the electricity produced in the United States, at a cost of over $11 billion to homeowners. As a result,roughly 100 million tons of carbon dioxide are released into the air each year—an average of about two tons for each home with an air conditioner. Switching to high-efficiency air conditioners and taking other actions to keep your home cool could reduce this energy use by 20%–50%.
System Sizing
Heat Load Calculation or Manual J—a technique that evaluates your home’s volume, construction methods and materials, window area, and arrives at the accurate heat nfiltration (or heat gain) in British thermal units so that an appropriately sized unit can be proposed for the replacement. Older space conditioning systems (more than 10 years old) are often unreliable and much less efficient than a modern system. When it's time for a new replacement, choosing one of the correct size (heating and/or cooling output) is critical to getting the best efficiency, comfort, and lowest maintenance and operating costs over the life of the new system. Some national surveys have determined that well over half of all HVAC contractors do not size heating and cooling systems correctly.
The most common sizing mistake is in oversizing. This not only makes the new system more expensive to install, but also forces it to operate inefficiently, break down more often, and cost more to operate. Oversized heating equipment also often creates uncomfortable and large temperature swings in the house. Oversized air conditioners (and heat pumps) do not run long enough to dehumidify the air, which results in the "clammy" feeling and unhealthy mold growth in many air-conditioned houses (see dehumidifying heat pipes as one solution to this problem).
Incorrect Sizing Methods
It is the installer/contractor's job to perform the correct sizing calculation for the building. However, many installers only check the "nameplate" (the label on the unit that has the Btu per hour output among other things) of the existing system and sell you one just like it, or even worse, one that's larger. This is a not a correct sizing method and not in your best interests! Other methods include simple "rules of thumb" based on the size of your home or using a chart that accounts for a variety of factors. While these methods might provide a first estimate, they should not be used to size your system.
Why Most Older Systems are Oversized
Before the era of tightly constructed homes, it was not uncommon to install furnaces and air conditioners that had two to four times the necessary capacity. Since many people have added new windows, caulking, weather-stripping, and insulation to their homes, going by the nameplate is likely to result in an oversized system. Making improvements such as these to reduce heat loss in the winter and heat gain in the summer should allow you to install a smaller system while still being comfortable, as
well as saving large amounts of energy.
Manual J and Manual D: The Correct Way to Size a System
Correct system sizing requires considering many factors other than simply reading the nameplate of the existing unit. Key factors for correctly sizing a heating and cooling system include the following:
- The local climate
- Size, shape, and orientation of the house
- Insulation levels
- Window area, location, and type
- Air infiltration rates
- The number and ages of occupants
- Occupant comfort preferences
- The types and efficiencies of lights and major home appliances (which give off heat).
Homeowners should insist that contractors use a correct sizing calculation before signing a contract. This service is often offered at little or no cost to homeowners by gas and electric utilities, major heating equipment manufacturers, and conscientious heating and air conditioning contractors. Manual J, "Residential Load Calculation," published by the Air Conditioning Contractors of America (ACCA), is the recommended method for use in the United States. There are also many user-friendly computer
software packages or worksheets that can simplify the calculation procedure. You should make sure that the procedure used by the contractor follows Manual J.
What is a SEER Anyway?
SEER—Seasonal Energy Efficiency Ratio—is a term used in thermodynamics that reflects how efficient the unit is. The higher the SEER rating of a unit, the more energy efficient it is. The SEER rating is the btu (BTU—British Thermal Units. Air conditioners are sized by tonnage. A ton of air conditioning produces 12,000 btus of cooling capacity. A five-ton unit would provide 60,000 btus of cooling.) of cooling output during a typical cooling-season divided by the total electric energy input in watt-hours
during the same period.
SEER rating more accurately reflects overall system efficiency on a seasonal basis and EER reflects the system’s energy efficiency at peak day operations. Both ratings are important when choosing products. As of January 2006, all residential air conditioners sold in the United States must have a SEER of at least 13. ENERGY STAR qualified Central Air Conditioners must have a SEER of at least 14. Today, it is rare to see systems rated below SEER 9 in the United States because aging, existing units are being replaced with new, higher efficiency units. The United States now requires that residential systems manufactured after 2005 have a minimum SEER rating of 13, although window units are exempt from this law so their SEERs are still around 10. Substantial energy savings can be obtained from more efficient systems. For example by upgrading from SEER 9 to SEER 13, the power consumption is reduced by 30% (equal to 1 - 9/13). It is claimed that this can result in an energy savings valued at up to US$300 per year depending on the usage rate and the cost of electricity.
Maintenance should be performed regularly to keep their efficiencies as high as possible.
But when either replacing equipment, or specifying new installations, a variety of SEERs are available. For most applications, the minimum or near-minimum SEER units are most cost effective, but the longer the cooling seasons, the higher the electricity costs, and the longer the purchasers will own the systems, incrementally higher SEER units are justified. Residential split-system ACs of SEER 20 or more are now available, but at substantial cost premiums over the standard SEER 13 units.
Calculating the annual cost of power for an air conditioner.
Air conditioner sizes are often given as "tons" of cooling where 1 ton of cooling is defined as being equivalent to 12,000 BTU/h. The annual cost of electric power consumed by a 72,000 BTU/h (6 ton) air conditioning unit operating for 1000 hours per year with a SEER rating of 10 and a power cost of 12¢ per kilowatt-hour (kW·h) may be calculated as follows:
unit size, BTU/h × hours per year, h × power cost, $/kW·h ÷ SEER, BTU/W·h ÷ 1000 W/kW
Example:(72,000 BTU/h) × (1000 h) × (12¢/kW·h) ÷ (10 BTU/W·h) ÷ (1000 W/kW) = $864 annual cost
If you’re not into equations, we’ve decided to make it a little simpler to follow. The next page contains a spreadsheet that will show you the typical energy use for a home in West Florida, with a 3 ton, 10 SEER unit, that has the indoor temperature set at 78 degrees in the summer. At your appointment with us, we can load your actual size unit into the spreadsheet, and give you a good idea of what to expect when it comes to your actual power savings.
SEER Savings Calculation
| Your Tonnage | 3 Your BTUH | 36000 | |
| Hours Run Time Annually | 2800 | West Florida Avg | |
| Power Cost: | 0.12 | Monthly Cost | |
| Your Annual Cost at 10 SEER | $1,209.60 | $100.80 | |
| New Seer | Projected Annual Cost |
Projected Annual Savings | Projected Monthly Savings |
| 13 | $930.46 | $279.14 | $23.26 |
| 15 | $806.40 | $403.20 | $33.60 |
| 16 | $756.00 | $453.60 | $37.80 |
| 18 | $672.00 | $537.60 | $44.80 |
Heat Pump Systems: Do I need one? Do I want one?
For climates with moderate heating and cooling needs, like west central Florida, heat pumps offer an energy-efficient alternative to furnaces and air conditioners. Like your refrigerator, heat pumps use electricity to move heat from a cool space into a warm, making the cool space cooler and the warm space warmer. During the heating season, heat pumps move heat from the cool outdoors into your warm house; during the cooling season, heat pumps move heat from your cool house into the warm outdoors. Because they move heat rather than generate heat, heat pumps can provide up to 4 times the amount of energy they consume.
The most common type of heat pump is the air-source heat pump, which transfers heat between your house and the outside air. If you heat with electricity, a heat pump can trim the amount of electricity you use for heating by as much as 30%–40%. High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months. However, the efficiency of most air-source heat pumps as a heat source drops dramatically at
low temperatures, generally making them unsuitable for cold climates, although there are systems that can overcome that problem.
Heat Pump Operations
Proper operation of your heat pump will save energy. Continuous indoor fan operation can degrade heat pump performance and increase the humidity level in your home. Operate the system on the "auto" fan setting on the thermostat.
Like all heating and cooling systems, proper maintenance is key to efficient operation. The difference between the energy consumption of a well-maintained heat pump and a severely neglected one ranges from 10%–25%.
Clean or change filters once a month or as needed, and maintain the system according to manufacturer's instructions. Dirty filters, coils, and fans reduce airflow through the system. Reduced airflow decreases system performance and can damage your system's compressor. Clean outdoor coils whenever they appear dirty; occasionally, turn off power to the fan and clean it; remove vegetation and clutter from around the outdoor unit. Clean the supply and return registers within your home, and straighten their fins if bent.
You should also have a professional technician service your heat pump at least twice every year.
Advanced Technology
A number of relatively new innovations are improving the performance of heat pumps.
Unlike standard compressors that can only operate at full capacity, two-speed compressors allow heat pumps to operate close to the heating or cooling capacity that is eeded at any particular moment. This saves large amounts of electrical energy and reduces compressor wear. Two-speed heat pumps also work well with zone control systems. Zone control systems, often found in larger homes or homes with multiple living arrangements, use automatic dampers to allow the heat pump to keep different rooms at different temperatures.
Some models of heat pumps are equipped with variable-speed or dual-speed motors on their indoor fans (blowers), outdoor fans, or both. The variable-speed controls for these fans attempt to keep the air moving at a comfortable velocity, minimizing cool drafts and maximizing electrical savings. It also minimizes the noise from the blower running at full speed, making these systems some of the quietest available on the market today. As a bonus, these systems run on low speed nearly 90 percent of the
time, which maximizes the humidity removal and increases both the comfort in the home and indoor air quality.
Another advance in heat pump technology is the scroll compressor, which consists of two spiral-shaped scrolls. One remains stationary, while the other orbits around it, compressing the refrigerant by forcing it into increasingly smaller areas. Compared to the typical piston compressors, scroll compressors have a longer operating life and are quieter. According to some reports, heat pumps with scroll compressors provide 10°–15°F (5.6°–8.3°C) warmer air when in the heating mode, compared to existing heat pumps with piston compressors.
Air Conditioning 101
Air conditioners employ the same operating principles and basic components as your home refrigerator. Refrigerators use energy (usually electricity) to transfer heat from the cool interior of the refrigerator to the relatively warm surroundings of your home; likewise, an air conditioner uses energy to transfer heat from the interior of your home to the relatively warm outside environment.
An air conditioner cools your home with a cold indoor coil called the evaporator. The condenser, a hot outdoor coil, releases the collected heat outside. The evaporator and condenser coils are serpentine tubing surrounded by aluminum fins. This tubing is usually made of copper.
A pump, called the compressor, moves a heat transfer fluid (or refrigerant) between the evaporator and the condenser. The pump forces the refrigerant through the circuit of tubing and fins in the coils.
The liquid refrigerant evaporates in the indoor evaporator coil, pulling heat out of indoor air and thereby cooling your home. The hot refrigerant gas is pumped outdoors into the condenser where it reverts back to a liquid, giving up its heat to the outside air flowing over the condenser's metal tubing and fins.
Ask about Proper Installation of your new equipment
Replacing your old heating and cooling equipment with new, energy-efficient models is a great start. But to make sure that you get the best performance, the new equipment must be properly installed. In fact, improper installation can reduce system efficiency by up to 30 percent — costing you more on your utility bills and possibly shortening the equipment's life.
Finding Qualified Equipment:
The Consortium for Energy Efficiency (CEE) and the Air-Conditioning and Refrigeration Institute (ARI) have developed an online database which can be used to find qualifying ENERGY STAR equipment. All equipment listed in this online database meets the specification requirements for ENERGY STAR. This online database is solely maintained and operated by CEE and ARI. Your contractor should furnish you with the ARI certificate for your system to ensure the efficiency of the system is as promised. You can check it yourself at www.ari.org.
Available Rebates, Tax Credits, and Incentives
Rebates and incentives are available, but they are dependent on a variety of qualification factors. If your power is supplied by TECO or Progress Energy, rebates are available if you opt for a heat pump system greater than 15 SEER. The rebate amount varies depending on the type of unit you currently have, the efficiency of the unit you install, and the inspection performed by the power company after the installation. TECO rebates are discounted off of the price of the unit; Progress Energy rebates are
delivered in the form of a credit on your power bill.
Manufacturers often offer cash incentives. Please check with your representative for current rebates.
Tax Credits for Consumers:
Home Improvements
Tax credits are now available for home improvements:
- must be "placed in service" from January 1, 2009 through December 31, 2010
- must be for taxpayer's principal residence, EXCEPT for geothermal heat pumps, solar water heaters, solar panels, and small wind energy systems (where second homes and rentals qualify)
- $1,500 is the maximum total amount that can be claimed for all products placed in service in 2009 & 2010 for most home improvements, EXCEPT for geothermal heat pumps, solar water heaters, solar panels, fuel cells, and small wind energy systems which are not subject to this cap, and are in effect through 2016
- must have a Manufacturer Certification Statement to qualify for record keeping, save your receipts and the Manufacturer Certification Statement
- improvements made in 2009 will be claimed on your 2009 taxes (filed by April 15, 2010) — use IRS Tax Form 5695 (2009 version) — it will be available late 2009 or early 2010
Definitions of ratings:
Heating Seasonal Performance Factor (HSPF):
This is a measure of a heat pump's energy efficiency over one heating season.
Energy Efficiency Ratio (EER):
This is a measure of the instantaneous energy efficiency of cooling equipment.
Seasonal Energy Efficiency Ratio (SEER):
This is a measure of equipment energy efficiency over the cooling season.
Can’t I Just Replace a Piece of the Unit?
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| Condensing Unit | Air Handling Unit | Packaged Unit |
After March 1, 2009, permits to install units won’t be issued in most counties in Florida for equipment that doesn’t meet the federally mandated minimum of 13 SEER. That means if you have a newer “piece” of equipment that CAN be matched with another piece to produce the 13 SEER, you’re covered. If the piece is 3 years of age or older, it might be difficult to find a piece. Quality contractors don’t recommend “piecemealing” systems together, as it isn’t in the consumer’s best interest. With the warranties and
efficiencies available today, it is best to replace the entire system.
Permit!? Did you say PERMIT?!
You bet. It is for your protection! The building codes are in place to protect homeowners and ensure their safety. If anyone says that permits drive up the cost of unit, they’re right, in a way. It keeps people from cutting corners that compromise the equipment’s longevity and your safety!
Here’s the process:
1. A licensed contractor applies to the county for a replacement unit permit.
2. Then, they post the permit at your home and install the unit, bringing everything surrounding the unit into compliance with the current codes.
3. After installation is complete, an “inspection” is called in and a county inspector visits the home, checking for compliance with the code.
4. The inspection either passes or fails. If it fails, a “tag” is left, listing the infractions.
Don’t use anyone who works without a permit. It puts you at risk!
A Word About Brands
In this day and age, most equipment is reliable. In fact, the most brands use Copeland Scroll compressors! Brands are really a matter of preference from the consumer’s standpoint. Look for the factory parts warranty, which should be 10 years and don’t settle for less. Lifetime compressor warranties are a nice, safe bonus. What really matter is the installation. Any brand works well when installed properly, and every brand will fail when installed without attention to details like copper sizing, static pressure in ductwork, and proper seals and sizing for your application. The labor warranty lets you determine how long the contractor is responsible for the repair bills, and with a purchase of this magnitude, it ought to be at least 10 years. If a compressor fails after the installing contractor’s labor guarantee lapses, it could mean upwards of $600 in bills for you.
Indoor Air Quality
Lots of people suffer from allergies and asthma. Billions of dollars are spent annually on room air cleaners and filters to improve the quality of their indoor air, which often (according to the American Lung Association) contains more irritants than outdoor air. Americans spend 80 percent of their time indoors, so making the air we breathe the cleanest it can be is certainly a priority. That priority escalates when someone in the family is suffering. Whether it is a child with asthma, an adult suffering from allergies and migraines, or someone with a compromised respiratory system, your air conditioner can help! That’s right: your air conditioner can be part of the solution.
Three Steps to Better Indoor Air Quality
In truth, there are three steps to improving the air.
1. Remove source pollutants. No smoking, etc.
2. Filter out the pollutants.
3. Dilute, or add fresh outside add to pressurize the home and minimize the contaminants.
Sounds easy, right? When you consider the hundreds of types of filters out there, and then add to that hundreds more indoor air quality devices like UV lights, then mix it all up with your specific problems and contaminants, indoor air can get downright confusing. There is a great way to sort it out.
One great way is to address the humidity in your home. The optimal humidity for human life is 50 percent. That level, however, is not optimal for a dust mite! At that humidity level, dust mites can’t thrive or reproduce, molds can’t form and spore, and lungs breathe easy. Easy solution, right? All it takes is a correctly sized air conditioning system and a system designed for optimal humidity removal. There are many systems that have thermostats that can control both humidity and temperature. Be sure to ask for options that perform in this way if allergies or asthma is a concern for your family. You can’t afford not to! Make sure the thermostat is able to be set to detect and respond to humidity calls as well as temperature calls, and ensure the operation of the unit by requiring a variable speed air handler (a two-speed compressor is optimal) be pair with that thermostat.
Don’t buy any filtration system until you know precisely what’s in your air. Some homes have an abundance of particulate, while other have issues with volatile organic compounds (VOCs); some homes have both. People spend lots of money that they don’t have to by trying to filter out the wrong things. Using an analytical device call the AirAdvice, you can determine exactly what’s in your air, where your humidity levels are, and pinpoint exactly which solution is appropriate for your problem without spending more than you need and getting an extremely effective solution. (Bayonet Plumbing & AC will be glad to perform the AirAdvice test for you.)
Humidity percentage
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This chart shows the humidity levels at which the listed microbes and health problems are likely flourish. As the width of the bar increases, indoor air quality diminishes and potential health problems increase. For example, virus growth is unsupported at humidity levels of 50% to 70%, but its growth rates steadily increase above and below this maximum growth at 0% and 100% relative humidity. |
Types of Filters Available
The Main Types of Filters are Media Filters, Electronic Air Cleaners, Photocatalytic Air Cleaners, HEPA filtration systems. Each will be explained in brief below.
Media Filters: these are whole house filters installed on the return side of your air handler or furnace. They provide the added benefit of keeping your coil clean, which helps keep your system running efficiently. If you have multiple returns in your home, all of the filters can be removed when this one is installed (and should be to prevent problems). All media filters are not created equal! They are rated with a MERV rating system. ($$)
MERV ratings are used to rate the ability of an air conditioning filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminats pass through the filter.
MERV ratings range from 1 - 16 and measurements are in microns. Some of the common particles related to MERV ratings are pet dander, insecticide dust, smog, dust, viruses, wood, tobacco smoke, spores, bacteria and pollen.
Some of the most common filters found in residential use only have a are typically disposable panel type filters and do not do a good job of filtering the air because they will
not stop particles smaller than 10 microns. Merv 5 to 8 rated filters are a better choice and are more commonly found in commercial applications. These filters will collect particles as small as 3 microns and are a good choice for home owners also.
Filters with a merv rating of 9 to 12 are used in commercial and industrial appliactions will stop particles in the 1 to 3 micron range. These filters are a great choice for home owners who want the best dust control possible. When using filters with Merv 9 ratings and above it is important to clean or replace them when recommended by the manufacturer because they will have a negative effect on air flow when they become dirty. This can lead to performance problems and decreased operating efficiency.
The most efficient filters have merv ratings of 13 to 16 and will stop particles as small as .3 microns. These filters are used in hospitals and other super clean environments.
Most media filters need replacing annually, but some will need replacement every 6 months dependent on living conditions.
HEPA Filters: Before getting into details about hepa air filters it is important to first answer a commonly asked question regarding the word HEPA. What does hepa stand for? HEPA is an acronym which stands for High Efficiency Particulate Arrestance. To qualify as a HEPA filter, the filter has to capture a minimum of 99.97% of all particles 0.3 microns in diameter. That is about 300 times smaller than the diameter of a human hair and smaller than we can see.
Hepa air filters are among the most efficient air conditioner filters available. At over 99 percent efficient, a hepa air filter will remove almost all allergens from the air that passes through your HVAC equipment. Hepa air filters remove dust mites, pet dander, pollen, mold spores and other household allergens.
Hepa air filters are commonly used in environments where very clean air is a must, such as clean rooms, hospital wards, surgical rooms and other places where maximum dust removal is very important. Hepa filters are also used in many other applications such as very efficient hepa vacuum cleaners and HEPA air cleaners. They do, however, require strict maintenance to maintain performance. They are typically expensive to install and do not provide any protection for your coil.
Electronic Air Cleaners: these units require a small amount of electricity to operate and produce a small amount of ozone as a by-product. They are attached to your indoor unit (air handler or furnace) and they work by adding an ionic charge to airborne particles and then attracting them to collector plates. They are slightly more expensive to purchase and install, but do not require filter changes, as the electronic cells are washable. As with all electronics, the electronic cells and ionizing wires can wear out or break, so be careful when choosing this option. ($$$)
Filters with Photocatalytic Oxidation: in simplest terms, this is the best of all solutions, providing a broad spectrum solution without ozone. A great example is Lennox’s PureAir. It uses a MERV 16 media filter in conjunction with a bank of UVa lights with titanium-dioxide coated plates that provide a photocatalytic effect on air passing through the plates. In layman’s terms, this filter removes all smells, odors, and VOCs from the airstream. In scientific terms, it hydrolyzes bioaerosols. Either way, when paired with a humidity-controlling system, this is the penultimate option.
This article was composed for Bayonet Plumbing, Heating, and Air Conditioning Inc’s customers by Bayonet sales manager Kris Blankenship. Please do not reproduce without permission, but please feel free to bombard us with your questions. We hope you feel a little more prepared to evaluate and state your needs and more comfortable with the ins and outs of an AC system.
To download a PDF of this article, click here.
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