At PM-EXPO Orlando last Tuesday, we heard from a number of property managers who were having problems with their central air conditioning units as Florida’s summer heat causes the mercury to rise. Here’s a 10 point refresher to review before hiring an HVAC contractor in Florida:

1. How to I determine the best size for my HVAC system?

A number of factors need to be considered when sizing an HVAC to a building. A professional HVAC contractor uses a protocol called Manual J. Considerations include cubic feet, type of construction, insulation, average outdoor temperatures in summer and winter in your part of Florida, types of floors, windows and doors, how many people use the building, infiltration quality and whether or not there are fireplaces.

2. What exactly does S.E.E.R. mean?

S.E.E.R. stands for Seasonal Energy Efficiency Ratio. S.E.E.R. rates how much cooling an air conditioner will deliver per unit of electricity consumed – the higher the S.E.E.R., the more efficient the central air conditioner. Mid-range S.E.E.R. range from 13 – 17.

3. Does the tonnage of an HVAC system correspond to an amount of BTU’s?

Each ton of air conditioning and heating systems equals about 12,000 BTU.

4. Are there any simple things that I can do to make the HVAC work more efficiently?

Change filters regularly and use curtains, drapes or shutters to protect against the hot sun. Sun shading window film can also decrease stress on the AC.

5. How does the size of a central air conditioning system effect energy consumption and effectiveness?

Central air conditioning systems that are too small won’t keep the area cool enough but will use less energy – even if the air conditioner is running all the time. This is because a central air conditioner uses the most energy when it is cycling on.

An oversized central air conditioner will burn more energy, will cool sufficiently but will not control humidity well. The HVAC cycle will cool too quickly and not stay on long enough to reduce humidity.

6. How much cooler should the air cycled through the HVAC be than the outdoor air?

A central air will typically cool the air about 20 degrees lower than the outdoor air during the  Florida summer – after the air conditioner has been running 10 or 20 minutes. But if it is not very hot outdoors, the air produced may be only about 15 degrees cooler than outdoors. The more humid it is outside, the less the HVAC will cool the air.

7. What is the best temperature to set my thermostat during the Florida summer and winter?

It is usually recommended to set your thermostat between 78-80 during the hot Florida summer and that you set your heating system to about 68-70 during the winter.

8. What are the differences between electronic and mercury thermostats?

Electronic thermostats are more accurate than mercury-based thermostats. Programmable thermostats are most efficient because you can make different temperature settings for different times of the day.

9. What should I check before calling an HVAC company for service?

Make sure the breakers are on, the thermostat is correctly set and the the air handler is plugged in. People hate wasting money on service calls only to realize that they forgot to do something simple.

10. Is it a good idea to conserve energy by closing registers to areas that we do not use?

Closing registers is not advisable. Central air ductwork is designed to maximize efficiency with proper airflow. Closing registers will cause the central air to cycle more frequently.