Air Conditioning Equipment

Air Conditioning Equipment

SEER:
Air conditioning equipment has gone through some major changes affecting both comfort and efficiency. The lowest SEER (seasonal energy efficiency ratio) equipment manufactured today is 13 SEER. The highest is over 25 SEER. Higher SEER systems are going to cost more. They can come with multiple compressors, dual or oversized coils and a host of electronic improvements. All this efficiency adds to both the initial cost and the cost to maintain them, and cost it will. A new DC blower motor with module can run as much as $1200 for an out of warranty repair cost. Most manufactures provide (in the cost of the equipment that is) a ten year limited compressor warranty and at least five years on parts. In addition, we recommend you at least consider purchasing the extended labor warranty when available.

Evaluating Cost vs Savings:
In evaluating the purchase of a new system, consideration should be given to the payback period. As an example, let us say the savings between a 15 SEER and an 18 SEER system was $15 a month (for six months of cooling per year) over the 14-year life span of the equipment. That equals $1260.00. If the 18 SEER system cost $3000 more than the 15 SEER, that would not be a wise investment, especially with the added cost of maintaining a highly technical system. A good value and shorter payback period can be found in the 15 to 17 SEER systems.

Heat Pumps:
We still get questions about heat pumps. What is the difference between a heat pump and an air conditioner? Do heat pumps work well in our area? Are heat pumps more efficient?

A heat pump is an air conditioner until winter when the cycle reverses and the heat pump extracts heat from the outdoor air and transfers it to the indoor air. Air conditioning systems are just as efficient as heat pumps for cooling; the difference is in the heating season where heat pumps can supply on average, three times more heat than the same amount of energy used for electric heating alone. This is measured as COP or (coefficient of performance).

Consideration should be given to the cost associated with repairs on the additional components that make up the heat pump system. There are reversing valves, accumulators, defrost boards, sensors and circuit boards and even a difference in thermostats. A heat pump will also have a back up electric heat element as supplemental heat for colder outdoor temperatures. Heat pumps work well down to about forty degrees when they struggle to keep up with the heat loss of the structure. They will still remove heat from the outdoor air, even down to zero degrees. Heat pumps also need to defrost themselves about once an hour in colder temperatures. This can be aggravating from a noise concern if too close to bedrooms windows. As the system defrosts, the electric strip is turned on to help warm the indoor air while the system reverses the cycle.

Variable Speed Motors:
One of the best improvements has been the change from a single speed blower motor in the air handler to a variable speed motor. These units were primarily developed for the more humid climates. They are more efficient at removing humidity and designed to deliver the required amount of air across the cooling coils despite minor issues. When replacing existing systems with the newer equipment, it is important to note any existing design discrepancies that could affect the efficiency of the new system including refrigerant line sizes, air duct static pressures, duct and grille sizing.

Compressor Staging:
Air conditioning or heat pump outdoor units have gone through some changes also. Lower sound levels, multiple speed fan motors, on board diagnostic controls, improved on-demand defrost systems plus more forgiving and efficient scroll compressors. Efficiency improvements also include compressor staging which allows the air conditioning compressor to run at a lower output until the maximum output is needed.

Newly Designed Air Handlers: 
American Standard has a newly designed air handler called the Forefront that has some key benefits. They have eliminated the typical fiberglass insulation and gone to a foam filled cabinet. This helps eliminate sweating in attics and garages. Gone also are the screws and stripped out screw holes, replaced by quarter turn latches for easy access. The cooling coil is easily accessed for inspection and cleanings. To improve the operating efficiency a motorized metering device assures accurate delivery of refrigerant under varying conditions and loads. The super quiet, patented “Vortec” blower was mounted at the bottom of the air handler to help reduce cabinet sweating. Molded-in door seals assure no air leakage. Quiet, efficient and ease of service makes this air handler number one in our line up.

Dehumidification is relatively a small function of air conditioning systems. They are primarily designed so that 70% of the work is transferring heat and around 30% removing moisture. Aprilaire has a line of dehumidifiers that are designed to reduce moisture, not lower the temperature. The model 1750 can remove as much as 90 pints (or 90 lbs) of water a day. They can reduce your homes humidity level without having to lower the temperature with your cooling equipment. The units are designed to work with your central air conditioning equipment or can be used independently. If you have high humidity due to a large amount of live plants, fish aquariums, indoor fountains etc., consider an Aprilaire dehumidifier. If you have high humidity levels but none of the above, you may have a problem with your system such as a low refrigerant charge or drain issues. A normal humidity level should be around 50%. Dust mites cannot survive at this level or below. At levels below 30%, static electric can be encountered.

Solar Systems:
Lennox has a new “Green” system that combines solar power with an air conditioner. This sounds like a good idea on the surface, but considering the total cost verses payback, perhaps not. It may be great if you are going to stay in the same house and the airside of the system would last twenty years. The average life span of a system in our area is twelve to fourteen years. The system itself (without the solar panels) is upwards of $8000, and installation cost. The solar panels are around $3000 each and even with the maximum of fifteen, it will not supply 100% of the power needed to run the system. At around $50,000, you just might be seeing green. There is a plus side, it is our understanding that when the air conditioning system is not operating, power generated from the panels can be used elsewhere or sent into the grid for a credit.

Sizing a System:
The proper sizing of an air conditioning system is based on load calculations by industry standards and will take into account the type and amount of windows, doors, roof color, square footage of the home, amount of people plus other heat and humidity factors. Between 500 and 600 square foot per ton has been used as a quick rule of thumb in our area for years, however this is only a rule of thumb and a proper load calculation should be used for accurately sizing an air conditioning system. Homes built within the last twenty years most likely had a computerized load calculation done before the home was built, as homes were required by the State of Florida to meet certain energy standards prior to permitting.

Coils:  Copper vs. Aluminum
For years, air conditioning coils have been made of both copper and aluminum and aluminum alone. The industry trend seems to be toward all aluminum. The main reason for aluminum is the elimination of formicary corrosion, which leads to leaks. This occurs when two dissimilar metals are in contact with moisture. Aluminum coils are generally thicker than copper and it is our experience over the last thirty years, have much fewer leaks. When a leak repair is required, copper coils are easier, provided the leak is accessible. Both excel at the transfer of heat.

Run Times:
Air conditioning run times will vary widely with the size of the system, the outdoor temperatures, the temperature setting on the thermostat, insulation levels, activity in the home, etc. Generally speaking, on days that are above 95 degrees, expect the system to run 90% of the time. 95 degrees is an industry standard that system sizing is based around. If the system was sized larger, it may not run long enough on milder days to remove the humidity in the home to a comfortable level. Bigger does not mean better in air conditioning. Systems do not remove humidity when they are off.

A system that only stays off for a few minutes could indicate a low level of insulation or some other factor such as an oven on or doors open. It is the heat gain in the home that cycles the air conditioner on, and the removal of that heat that cycles it off.
Air conditioning preventative maintenance should be performed at least once a year preferably in the spring. Please see our section on maintenance for more information.

Variable Speed Compressors:
This is the latest technological advancement in the air conditioning industry, however it is not new to the refrigeration industry where it has been in use for years.

It works much like the variable speed blower motors that we have come to accept as part of our higher efficiency equipment. An electronic module or in this case a “drive”, communicates with the air handler and thermostat to operate at just the right speed to match the required Btu load.

American Standard/Trane systems are currently rated at 18 and 20 SEER. They are expected to have models that can reach 25 and higher SEER ratings soon.

Longer run times improve comfort by removing more humidity and leveling out temperature swings, common with most systems. It also reduces compressor start-ups which is responsible for a major portion of the air conditioning electric bill. Run times of 18 hours at a very low wattage, would not be uncommon in peak cooling season.

This is relatively new technology in the air conditioning industry and as a result the verdict is still out on whether they will hold up under conditions of poor power supply, lightning and extreme summertime conditions. If the torture testing done on these by American Standard/Trane is any indication, they should do well. They also incorporate three times the safety protection of a typical system.

They are fully communicating systems so expect the cost compared to a 15 SEER system to be substantially higher.

Call us at now at 813-661-7579 to schedule a preventative maintenance service on your system or to speak to our staff about an upgrade to a higher efficiency system.

What does SEER stand for?
SEER stands for Seasonal Energy Efficiency Ratio.

What does SEER mean?
Seasonal energy efficient ratio – The higher the number, the higher the efficiency.

What SEER system should i get?
In evaluating the purchase of a new system, consideration should be given to the payback period. As an example, let us say the savings between a 15 SEER and an 18 SEER system was $15 a month (for six months of cooling per year) over the 14-year life span of the equipment. That equals $1260.00. If the 18 SEER system cost $3000 more than the 15 SEER, that would not be a wise investment, especially with the added cost of maintaining a highly technical system. A good value and shorter payback period can be found in the 15 to 17 SEER systems.

What is the highest SEER air conditioning equipment available?
The highest system is currently over 25 SEER.
Do heat pumps perform well in our area?
Heat pumps perform very well in our area.

What is the latest technology in air conditioning equipment?
Variable Speed Compressors are now available in air conditioning systems. They have been used in the smaller ductless market as well as the refrigeration industry for some time. They offer some very high efficiencies and exceptional comfort levels. See our more extensive write up above.

What is the best air conditioning brand?
We prefer the American Standard brand.

How long should my air conditioner run?
Air conditioning run times will vary widely with the size of the system, the outdoor temperatures, the temperature setting on the thermostat, insulation levels, activity in the home, etc. Generally speaking, on days that are above 95 degrees, expect the system to run 90% of the time.

How long should my air conditioner stay off?
How long a system runs depends on several factors including insulation levels, set temperature -vs- outdoor temperature and cleanliness of system are among the top reasons.

How long should my heater run?
How long a system runs depends on several factors including insulation levels, set temperature -vs- outdoor temperature and cleanliness of system are among the top reasons.

How often should I have maintenance on my air conditioner?
Air conditioning preventative maintenance should be performed at least once a year preferably in the spring. Please see our section on maintenance for more information.

How often should I have maintenance on my heater?
At least annually. Some prefer semi-annually having it serviced both Spring and Fall.

What size air conditioner do I need?
Approximately 1 ton per 550 square feet of living space.

How is an air conditioner size determined?
It is determined with a load calculation.

How do I know if my air conditioner is too small?
Your air conditioner will run all the time.  It also will not pull the house temperature down to the set temperature.

How do I know if my air conditioner is too big?
The humidity will not be removed and the air conditioner system cools and shuts down quickly.

What is the difference between an air conditioner and heat pump?
A heat pump is an air conditioner until winter when the cycle reverses and the heat pump extracts heat from the outdoor air and transfers it to the indoor air. Air conditioning systems are just as efficient as heat pumps for cooling; the difference is in the heating season where heat pumps can supply on average, three times more heat than the same amount of energy used for electric heating alone. This is measured as COP or (coefficient of performance).

Which type of coil is better, copper or aluminum?
The industry trend seems to be toward all aluminum. The main reason for aluminum is the elimination of formicary corrosion, which leads to leaks. This occurs when two dissimilar metals are in contact with moisture.

Which coil is more energy efficient, copper or aluminum?
Both excel at the transfer of heat.

Can aluminum coils be repaired?
Aluminum coils are generally thicker than copper and it is our experience over the last thirty years, have much fewer leaks. When a leak repair is required, copper coils are easier, provided the leak is accessible.