Heating & Air Conditioning Basics

Forced Air vs. Hydronic

To understand how your home or office is heated and cooled, its important to first know what kind of system you have because different HVAC systems work in different ways.

Forced Air Systems work by blowing heated or cooled air through a series of “supply” ducts distributed throughout a building. The air exits the ducts through grills or registers (above, left) is cycled through the rooms and corridors, then returned through “return” ducts to the air handler.

Hydronic Systems are exclusively used for for heating. Hot water is pumped (or steam moves with its own pressure) through pipes to radiators (above, right) or baseboards located in rooms and corridors. These radiators or baseboards act as heat exchangers, allowing the heat from the water (or steam) inside to transfer to the air outside, warming the space.

Heating

Forced air systems most often heat air with a Furnace. Furnaces can work with a number of different fuel sources to create heat, but most common are natural gas, liquefied petroleum gas (LPG), or fuel oil. Hydronic systems use a Boiler to heat water. Boilers can also work with different fuel sources, but most common are natural gas or fuel oil.

The efficiency of Furnaces and Boilers is measured in annual fuel utilization efficiency (AFUE). Furnaces available on the market today range in efficiency from 78% to 96% AFUE, while boilers range from 80% to 99%. In the past, 80% furnaces and 55-65% boilers have been standard options, but today 90%+ AFUE furnaces and 85%+ AFUE boilers are recommended byEnergyStar®. You may also want to consider higher efficiency equipment to take advantage of available Tax Credits and Incentives.

Cooling

Most air conditioners consist of an indoor unit (evaporator coil) and an outdoor unit (condensing coil). Watch this video to learn how they work:

Like furnaces and boilers, air conditioners are rated on their efficiency. The most common rating is SEER (Seasonal Energy Efficiency Ratio). You can learn more about SEER here, but what you need to know is that the minimum rating for residential A/Cs is 13 as of 2006. EnergyStar® qualification requires a minimum of 14 SEER. A higher SEER rating will help you conserve power during the cooling system, which will help you conserve cash!