HVAC System Replacment
Your investment in your HVAC system is not a matter to be taken lightly. Some basic knowledge on how your HVAC works and interacts with your home's specific construction, site location, and layout, will help you make a better informed decision about selecting an HVAC contractor in order to perform a partial or complete HVAC system replacement.
Having the right "size" of unit is more important than selecting a particular "brand" of equipment. The most common mistake people make is replacing the old HVAC unit with the same size unit without performing an updated load calculation. It is possible for the old unit to be over-sized; however, even if the old unit was sized correctly, it may currently be over-sized. Additional home improvements such as insulation, new windows/doors, or weather stripping will reduce the size of HVAC equipment needed to cool your home. A load calculation must be performed on your home to determine the correct size before a new unit is purchased and installed. Heating units can be over-sized with no adverse impact, but A/C equipment should be sized within 10% of the required load calculation. An under-sized air conditioner usually will not cause problems other than struggling to completely cool the home on very hot days. However, homes with over-sized A/C units will not totally cool a home on 100 degree days and can experience the following issues:
- Poor Comfort - An over-sized air conditioner will not run long enough to distribute the air evenly, leaving hot and cold spots
- High Humidity - Air conditioners dehumidify the indoor air as it cools. If the unit is too large, it will cool the home down very quickly but not run long enough to remove the humidity. If you do not see water draining from your HVAC condensation pipes, it can mean they are clogged up or your A/C unit is not running long enough to remove the humidity from the indoor air. Ideally, indoor relative humidity should be in the 50%-55% range. Mold tends to grow when the humidity level exceeds 60% and over-sized A/C equipment can contribute to higher than desired humidity levels in a home.
- High Operating Cost - Relative humidity will affect the operating cost of running A/C units. The human body can feel just as comfortable at 78 degrees @ 55% relative humidity or at 73 degrees @ 65% relative humidity. The difference is that it costs less to keep the A/C thermostat set on 78 degrees than on 73 degrees. A home with a properly-sized air conditioner will allow you to keep the temperature higher while still feeling comfortable and will lower your overall operating cost. Over-sizing an air conditioner to keep cool is a fallacy!
An HVAC system consists of two main components: 1) the heating/cooling equipment and 2) the air distribution system (called Ductwork). High efficiency equipment will not provide the desired level of performance if it is placed in an a leaky, poorly insulated or poorly designed ductwork system. Ductwork systems in poor shape can result in an increase of 15%-20% in energy usage. Most of today's new high efficiency units require greater airflow and a home's original ductwork may not be large enough to allow proper operation to achieve the designed efficiency levels of newly installed HVAC equipment.
A ductwork system must be designed based on the heating or cooling load of each room. A room-by-room load calculation must be performed in order to determine the correct amount of cubic feet per minute of air flow to go into each room. Homes where the room-to-room temperature may vary significantly is often a result of improper ductwork sizing. Additionally, under-sized ductwork will result in high operating cost and shorten the life of compressors and heat exchangers due to continual inadequate air flow.
You can count on Comfort Keepers HVAC to provide honest and independent advice on selecting the type and size of equipment to best meet your HVAC needs. Many factors should be considered when selecting equipment upgrades. Please read through the educational information on this site and contact us so we can assist you in evaluating and choosing a contractor to meet your HVAC system needs. We are here for you!