What Type of HVAC System Should I Buy?
Possibly because you have never experienced the dilemma of replacing a heating and air conditioning system and the “BIG EVENT” is likely to happen or has already happened you are not current with the choices that are available for replacement. Statistics indicate that more consumers have not experienced this scenario than those who have. And there is a whole industry out there waiting for this event to happen and you only have a short time (days?) to make an informed choice. And some of those in the industry will lead you to purchase the system that best suits them, not you. How will you know what you need or want without doing some homework first? Where do you go to get the best advice? Of course, we think that should be us. If you are in learning mode, my advice is to enjoy the ride, if you can.
This article is about the types of heating and air conditioning systems available for replacement. And since you are making the effort to be informed, the experience can be a rather illuminating one before the purchase decision is installed. Afterwards, the chosen installation will impact approximately 30+% of your monthly power costs. Maybe more!
Let’s see if I can help your “lights” come on. There are systems with 3 different types of compressors (the main component of the system). I will compare the versions with an analogy to light bulbs. There are “incandescent”, “compact fluorescent”, and “LED” versions of AC systems.
Incandescent versions of heating and cooling are known as single stage systems utilizing a compressor that has two states, OFF or ON. This “single-staged” compressor is designed to cool your home on the hottest day of the summer and the “not-so-hot” days of the summer with the same rate of capacity all of the time.
If the temperature is, say 80 degrees outside (note that it has the capacity to cool on a 95-degree day), the cooling cycles should be relatively short. The system utilizes the 95+ degree capacity and quickly cools your home. While the system is off, the heat indoors increases above the thermostat set-point and causing the system to start cooling again.
- Did you know that the frequency of the start/stop cycles has a significant impact on the expected life cycle of the system?
- Did you know that a single-stage heating and air conditioning system consumes more energy at start-up than it does while running?
- Did you know that de-humidification is provided by air conditioning? Air that is cooled forces humidity out of the air when cooled. The removed humidity changes to water which is removed by the condensate lines that run from your indoor blower and carried outside. For an explanation of how a heat pump works go here.
- Did you know that air conditioners require 3 – 5 minutes of run time before any humidity is removed from the air? Did you know that you could be just as comfortable indoors at a slightly higher temperate if more humidity was removed from the air? You could save 1 - 3% for each degree the thermostat is raised above 72 degrees.
- Have you thought about the performance of the air filters on the system when your system is turned off? While off, there is NO air is going through your system, so absolutely no air filtration is occurring.
- Did you know that Santee Cooper’s utility rates have been increasing the past few years because of a mandated shift from producing coal-fired generation and shifting to higher cost solar powered alternatives and nuclear generation? Did you know that future cost increases are already approved? (Suggestion: Google this search string "santee cooper rate increase"). Even if you are not a Santee Cooper customer, your electric power supplier purchases power from Santee Cooper.
- Not only is the compressor single-speed but the blower fans (outdoor and indoor) have one speed. Why is this significant? It takes some knowledge of chemistry to understand this, but the density of air decreases with the replacement of air molecules with water molecules (humidity). Humid air is the LIGHTER dry air. To me that seems to be the opposite of what I would deduce. On moist days (when the humidity is greater than 60%), since the wet air is lighter, the air passes through through the indoor blower and outdoor fan faster than dry air, the air flows are faster than the "rated condition" of the system and the cooling capacity is reduced.
Even with all the short-comings of a heat pump system with single speed compressor and a single speed indoor blower, they are capable of sufficiently cooling indoor spaces. Are you starting to get the idea that there is a better method of air conditioning your home?
The better method of air conditioning your home is a cooling system that contains a compressor with 2-stages of capacity. I call it the “compact fluorescent” version of air conditioning. The fluorescent version contains a compressor with 2-stages of capacity and contains variable speed blowers for the indoor and outdoor fans. Unless the outdoor temperature is hot, the system cools your home while running at the lower speed. And many good results begin to occur!
- The cycles are longer which reduce the number of starts and stops which should positively impact the expected life cycle of your system.
- When the system starts, the system consumes less energy because it is starting at a lower capacity rating.
- Significantly decreased sound levels (from the outdoor and indoor systems) when running at a lower capacity level. Do you have a system that runs at loud levels that is located near your pool, deck or bedroom window?
- Since the cycles are longer, more dehumidification occurs with each cycle. Cycles are typically significantly longer than the systems with single stage compressors.
- With a 2-stage system and because of the reduced humidity, a higher temperature setting will result in equivalent comfort. (Warning here… if energy savings is your objective, don’t lower the temperature below the temperature setting utilized on your old system because your power bill is lower and you can now afford more comfort!)
- There is a chance that you may have to replace your ac filters a little more frequently because of the increased run time that provides better filtration of the indoor air. There may be a minimal increase in the number of filters you buy to provide a cleaner air space in your home.
- You will not have to pay increased power costs on energy savings achieved by a more efficient system. I suspect you won’t mind if you are paying less to your power company for increased comfort.
- The variable speed blowers (if properly installed) reduce the air flows from the fans to a rate that more closely match the “rated capacity” of your system. You really ought to read this article about variable speed air handlers, the indoor component of a system.
Did you notice that I referenced a 2-stage system as a BETTER method of air conditioning? I am sure you noticed that. If a single-staged system is a good method, the 2-stage system as a better method, then there must be a BEST method of heating and air conditioning. And there is! I reference it as L-E-D version of comfort. In the industry, we reference this type system as an “inverter drive” system. This type of heating and cooling system is like getting out on the interstate and “setting” the cruise control on your car!
The inverter drive compressor is one that provides a real low stage of capacity (30 – 40%) and has the capability to increase or decrease its capacity on the need (demand) for cooling. And it is designed to run long periods of time at the capacity needed to provide the comfort and humidity level settings on the thermostat.
- Very few cycles per hour… if starts and stops have been greatly reduced, do you think this feature should impact an expected life cycle of the system?
- Because of starting at very low capacities, the electrical requirement for variable speed systems at startup is greatly reduced.
- BEST humidity reduction possible is available from a system with an inverter drive… with variable speed blowers that are programmed to run at a matched speed based on the capacity of the inverter compressor.
- Quietest possible system…Do you have a deck, pool, or bedroom that would provide more utility if the heating and air conditioning system contributed little, if any, objectionable sound levels?
- Cleanest indoor air quality possible because of the long run times. With the addition of a whole house air cleaning system, your home could provide one of the most sterile environments that you frequent.
- Systems with an inverter drive provide the lowest monthly power costs available…at the highest possible level of comfort. Your power company may come to see you to see why your power costs decreased so dramatically!
- You control the temperature and the humidity level inside your home. Just dial it in (like cruise control in your car) and let the variable speed compressor serve you, your way.
- Inverter systems are the SMARTEST! They can communicate with humans to let humans know if they are running properly. If not properly operating, they can even communicate down to the component that isn’t functioning properly. They are even capable of reporting their “run-time” history to the internet to provide a technician what the problem is before he arrives to perform service. How smart is that?
- Even though I haven’t mentioned heating yet, I will now. A system with an inverter drive doesn’t need supplemental heat to provide heat on the coldest days of our winter. Systems with inverter drives are the KINGS of heating with heat pumps.
Now let’s make some sense out of these type of systems, the “incandescent, fluorescent, and LED versions of heating and cooling.
Incandescent (single-staged) systems start at 14 SEER (the minimum standard) and can achieve up to a 16 SEER rating.
Some EXAMPLES of our Single Stage Systems
Fluorescent (2-staged) systems typically range from 16 SEER up to 18 SEER.
Some EXAMPLES of our 2-Stage Systems
LED (inverter drive) systems range from 18 SEER to 20+SEER. Their HSPF (heating) efficiency ratings are significantly higher than the other types of systems (they don’t need supplemental heating in the winter).
Some EXAMPLES of our Inverter Drive Systems
I went to purchase replacement light bulbs for a ceiling fan recently in Lowes. The light bulb that blew was an incandescent bulb. When I got to the light bulb replacement aisle in Lowes, I went directly to the LED section because they last longer, use less energy, and emit less heat. Sure, the LED model cost more but it didn’t matter because I have no desire to make frequent attempts to replace a “hard-to-get-to” light bulb. That’s when the thought occurred to me to make the analogy of light bulbs to heating and air conditioning systems. And yes, the LED version of heating and cooling requires a significantly larger initial cost but with a significant list of added features and benefits with substantial energy savings. The concepts of oldest, older, and relatively new also applies to light bulb and heating and air conditioning replacements. I predict, as the year’s advance, the technology for heating and air conditioning systems will match the trends in indoor lighting.
If you are interested in getting a straight story about options to match your expectations, we do that with all of the customers we serve. We won’t try to sell you anything. We promote Trane, Bryant, and Ruud systems. Each of these manufacturers have all types of models described in this article. We will consult with you to select the system that best fits the requirements of your home and your needs and desires.