The Art of Heating and Cooling: How Thermostats Work

The thermostat is one of the smallest elements of your HVAC system, so it’s easy to assume it’s not a terribly important component. In fact, the thermostat is a key device that controls the operation of your heating and cooling system, so it plays a vital role the system’s performance, efficiency and your home comfort. This makes it essential to understand the kind of thermostat you have, how it works, and when you need professional help to solve thermostat-related problems.

Understand Your Type of Thermostat

Just by looking at your thermostat, it’s easy to tell which of these two main types you own:

• Mechanical. This manual device controls the temperature using a coil of two metal strips laminated together, along with contacts points that are adjusted using the thermostat’s temperature dial. The coil expands/contracts in response to temperature changes, and when it hits one of the contacts, it triggers your HVAC components to cycle on or off.
• Electronic. Instead of moving mechanical parts, these devices read the temperature with a thermistor that reacts to changes in electronic resistance. Typically, they have a digital display, and many models are programmable to provide greater energy savings. Some units have specialized “PID controllers” which allows them to control modulating/variable speed HVAC equipment. The most advanced are “smart” or “learning” units that streamline comfort, convenience and energy efficiency.

Common Thermostat-Related Issues

When problems develop with your HVAC system, it’s often hard to know if it’s equipment- or thermostat-related, so call your HVAC pro if you experience:

• Poor temperature control. If your home never hits the thermostat’s target temperature, it might be due to a low refrigerant level, or an off-level or poorly-calibrated thermostat.
• Short cycling. If your HVAC cycles on but shuts off too quickly, you may have improperly-sized equipment, or a dirty thermostat.
• Unresponsive equipment. If your thermostat screen goes blank, the unit may just need fresh batteries. If the HVAC equipment itself won’t cycle on, there may be disconnected/damaged wiring, or issues like a frozen evaporator coil.

For expert help solving thermostat problems in your Coastal Bend home, contact us at CCAC.