One of the most obvious reasons for the differences in efficiency is the air distribution systems. According to the DOE, leaking ducts are a top energy waster. Ducts can leak over time near connectors and register boxes but they can also become damaged and leak in the middle of a run as well. The state of Florida has also recently required duct sealing to accompany all equipment replacements per code. The installing contractor must certify that ducts are sealed.
Another reason why one system may perform better over another is that it is properly sized. Contractors should use a proper manual S sizing methods when replacing a system. This calculation factors everything from window sizing, insulation, ceiling height and even tree shade to determine what size system is the most efficient for a home. When a system is not properly sized, it may either short cycle or run forever. In either situation, it will be difficult to become comfortable as the humidity will be substantial with an oversized system and it will simply be too hot if your air conditioner is too small. Oversized air conditioners are a common problem in Florida and is estimated that more than 50% of the equipment today is too big for the application.
Other factors that could impact how well a system heats or cools is the length of the copper linesets, whether or not ductwork is properly sized, if the system has been maintained i.e. clean coils, clean filters and whether or not the system is properly charged.
The most commonly discussed rating for air conditioner performance is SEER. This provides a snapshot of how efficient an air conditioner is under a strict set of conditions. A SEER rating does not guarantee that your system will perform to that level. It could be better or worse. The higher the SEER, the more energy efficient the system is, except when comparing single and two stage compressor systems. Two stage compressors are tested in high stage although they will operate in low stage the majority of time in Orlando. This means that the compressor will run at 70% capacity and consume roughly 2/3 the energy. If you have more questions about efficiency ratings, contact the AC experts at Melco HVAC Services of Orlando. We offer free estimates on new system installations and guarantee that we will find the right efficiency system for your budget.