It all started with a simple question from a homeowner about their HVAC system and as I was writing an explanation for them to share with their HVAC tech, I realized this would make a good blog series. HVAC can be made simple OR complicated with a bad design. Here are some terms that your HVAC may use and here is what they are referring to in somewhat plain English:
HVAC- this is short for “Heating, Ventilation, and Air Conditioning” It refers to the complete system that is typically installed in most homes.
Thermostat– this is the main control for the HVAC system. Based on factors such as temperature, humidity, time of day and time of the year it gives the control board on the HVAC unit instructions on what is needed to create a comfortable environment. There are several types of thermostats commonly used such as programmable, manual and smart thermostats. We recommend programmable at a minimum to maximize comfort and efficiency. Smart thermostats are handy as well since they can learn your behaviors and make adjustments accordingly. Some thermostats can also be integrated in to smart home systems and controlled on smart phones.
Heat Pump (air sourced)- This system transfers heat to cool or heat up a home. The most common is air sourced (versus ground sourced) which means you will have a visible condenser outside your home which connects to the evaporator coil inside the unit. Air blows across this coil to either heat or cool your space depending on what they thermostat is telling it to do. This system is less efficient when trying to combat extreme temperatures.
Heat Pump (ground sourced)- This is same as the air sourced heat pump with the exception of how it exchanges energy outside the built environment. Instead of an outdoor condenser, the condenser is a series of pipes in the ground that exchange heat directly with the ground. These are used in GA and are most common in very cold climates since ground temperature are more consistent the deeper you go in the ground. We have installed these and the loops have been drilled between 200-500 feet on most our installations.
AFUE– is the measure of “Annual Fuel Utilization Efficiency” of heating equipment per year. For instance, in a typical 80% furnace, 20% of the energy produced by natural gas is expelled as exhaust directly to the exterior. 90% is considered “high efficiency” and 95% AFUE is pretty common among most new gas-powered furnaces. We recommend at least a 90% efficient furnace.
SEER– is the “Seasonal Energy Efficiency Ratio”. It measures how efficient an air conditioner is over a typical cooling season. Total Cooling Output / Total Electricity Used= SEER rating. This is average for the whole cooling season so when is it already cool outside, the rating can be higher thus more efficient for that small sample and if it is hot outside the SEER rating for that small sample will be lower. SEER is important since your AS has to meet certain requirements based on US Department of Energy. In 1992 a minimum of 10 SEER was required increasing to 13 SEER in 2006. In 2015 our climate zone (Southeastern US) required an increase to 14 SEER. There are system out there that far exceed the minimum with ratings up to 42 SEER in some mini-split systems.
MERV– is the rating given to the filters in furnaces. The lower the rating, the more air and particles it allows through the filer. The higher the rating the better it filters out smaller particles. This better filtration sounds good unless your system was not designed for this filter. They can decrease the amount of air flow which increases energy consumption and can wear out the fan faster. A properly designed filtration system that is compatible with your HVAC is recommended.
NOTE: Will will continue to edit and add to this list as our clients ask more questions.
If this post was too basic for you- feel free to check out this website: The Energy Vanguard
