HVAC | Types of HVAC Systems
If you’ve done an energy efficiency assessment of your home, maybe had some additional insulation installed, and you’re hiring a heating or cooling systems professional then now’s the time to decide on the right HVAC system for your home.
Newer systems today provide many more options, such as variable fan speeds and multiple stages of heating and cooling.
Single or Multi-Stage?
Single-stage heating and cooling is popular in colder winter climates and hot and humid areas, respectfully, because the systems are set to provide comfort for the coldest or warmest days of the year. But that also means that a great majority of the time, these heating systems or air conditioners are operating at full capacity when they don’t need to be. That’s where a multi-stage system comes in handy and can save you energy and money.
You can get a single-stage system with variable fan speeds to create a variable air flow, says Donald Prather technical services manager for the Air Conditioning Contractors of America(ACCA). Though that variation is limited, he stresses. You may not experience much of a difference, because the heating or cooling unit is still working at its maximum output.
Zoned HVAC systems can heat or cool individual areas of your home by controlling zone valves or zone dampers inside the vents or ductwork, which selectively block the flow of air. Zoned systems can save you energy and money by only heating or cooling certain areas when you need it.
Humidifiers and dehumidfiers can be added as options to heating and cooling systems, and if you live in a very dry or humid climate these upgrades should definitely be on your list. About 50 percent relative humidity is considered optimal for humans.
With these systems you can automatically control the humidity levels in a home as you heat and cool, though this is not available through forced-water heating systems that use boilers. With humidity/dehumidification systems built into your furnace or air conditioning, you cannot control the humidity levels when the system is not on. If desired, you can add separate humidity/dehumification systems that do this.
According to the U.S. Department of Energy, modern conventional heating systems can achieve efficiencies as high as 97 percent, converting nearly all the fuel to useful heat for your home.
Heating units can be categorized into furnaces that provide heated air through ductwork, which is a popular type of heating system in the United States such as boilers that heat water for steam radiators or forced-water systems with baseboard radiators, electric heat and heat pumps. Furnaces generally use natural gas or propane for fuel, while boilers can use gas or oil.
Seek Annual Fuel Utilization Efficiency (AFUE) ratings (efficiency percentage) in the 80s and 90s. The national minimum for furnaces in the United States is 78 percent. Look for Energy Star-certified systems that are more energy-efficient, and consider sealed and combustion units that bring outside air directly into the burner and exhaust directly to the outside. These are the most efficient systems and do not pose a risk of backdrafting combustion gases.
All-electric furnaces have AFUE ratings of 95 percent to 100 percent, but they are not economical is many parts of the country. You can also consider electric heat pumps to heat or cool parts or all of your home. Some heat pumps can be added onto furnaces as well, to help use less gas or propane.
Radiant floors, or hydronic heating systems, often use piping under a floor. Flexible tubes are filled with water or a glycol solution to heat a concrete or other floor. These can be quite efficient and require either a boiler or heat pump. And they can be retrofitted, if carefully installed beneath wooden floor sheathing. Though radiant systems are much more effective if built into a concrete floor, which will retain the heat and release it slowly. – HGTV
HVAC | Types of Systems is continued on our next blog…