HVAC 101: How Thermostats Work

You might mistakenly think that your thermostat isn’t an important HVAC component because of its size. In reality, it’s the thermostat that controls your entire HVAC system, so it can affect the equipment’s performance, energy consumption and your comfort. This makes it vital to understand the basics of how thermostats work, what type you have, how to know if an HVAC problem is thermostat-related, and whether you need expert help to resolve the issue.

What Kind of Thermostat Controls Your HVAC?

It’s fairly easy to tell which of the two main types of thermostats you have once you learn some specific device characteristics:

• These manual thermostats control temperature using a coil made from strips of two different metals, as well as two contact points you adjust via the unit’s temperature dial. As the ambient temperature changes, the coil expands and contracts. When it hits a contact set point, it signals the HVAC equipment to start up or shut down.
• These devices don’t have moving parts, but instead detect temperature using a thermistor that reacts to differences in electronic resistance. They usually have a digital display, and many can be programmed for energy-saving setback periods. Electronic models equipped with “PID controllers” are specifically designed for use with modulating HVAC components, but “smart” electronic thermostats provide the greatest convenience, energy savings, and comfort control.

Understanding Thermostat-Related HVAC Issues

When problems crop up with your HVAC, it’s not always easy to determine if it’s thermostat- or equipment-related, so be sure to call for expert help if the issue is:

• Not enough cooling. If the thermostat’s temperature setting is never reached, it could be caused by improper calibration, or too low a refrigerant level.
• Unresponsive equipment. When you’re faced with a blank thermostat screen, putting in new batteries might solve the problem. If the HVAC equipment won’t start up, there may be damaged/disconnected wiring, or a more serious issue like a frozen cooling coil.
• Short cycling. A dirty thermostat or oversized equipment can both cause cycling problems.

For help solving thermostat problems in your Orlando home, contact us at Rinaldi’s Energy Solutions.

Our goal is to help educate our customers in Orlando, Florida and surrounding areas about energy and home comfort issues (specific to HVAC systems).