When to Replace a Bad HVAC Thermostat?

The use of an HVAC system during the summer and winter months is very common among American households. Air conditioning systems keep residents cool during the summer and warm during the winter.

Unfortunately, these systems can stop working at the worst possible time. Before changing the entire unit, check the other components to ensure they are not the problem. Most times it can be your own thermostat that is not working properly.

The thermostat, also known as a controller or thermoregulator, is one of the most important pieces in your HVAC system. The thermostat communicates with the HVAC and allows you to adjust the temperature in your house.

However, over time the controller can stop functioning properly, causing discomfort within the home. The following is a short guide on how to tell if a controller is going bad.

HVAC continues to turn On or Off

Thermostats should always be in communication with HVAC systems to provide the correct temperature in the home. Once the communication stops, this could mean the thermoregulator is malfunctioning and it might be time to replace it.

Typically, when communication stops, the wiring inside of the thermostat is damaged or frayed. This will ultimately stop the connection with the AC. If this is the case, we recommend hiring a professional HVAC technician to come and diagnose the problem. They will evaluate whether you need to replace the device or the wiring instead.

Thermostat Does Not Respond to Temperature Change

Your HVAC system should immediately respond to a temperature change on the thermostat by turning the fan on or off. When the system is changing temperatures, you should hear an immediate response.

To check this, test the T-stat by changing the temperature. Increase or decrease the temperature by 5 degrees. You should hear a click and then the air conditioner should turn on. If the heating and cooling system does not fire up, you may have a faulty thermostat.

Incorrect Thermostat Readings

Displaying the incorrect temperature is another reason it might be time to replace your T-stat. If the controller is showing the wrong temperature, the home may reach uncomfortable temperatures.

If there are any doubts about the controller readings, we recommend that you test the temperature. To perform the test, use a portable indoor thermometer. If the readings from the thermometer are different than the thermoregulator, contact an electrician to diagnose the problem.

Incorrect readings can result from short cycling. Short cycling happens when the heating and cooling system starts up but never reaches the desired temperature setting.

Old Thermostat

Most thermostats offer homeowners about 10 years of use. Around the 10-year mark, controllers become old and outdated. In such cases, upgrading to a newer thermoregulator is the best option.

For instance, if you want to upgrade from a manual thermostat to a programmable one. Programmable models work better than manual ones, allowing you to set intervals of heating and cooling. An example of a programmable controller is King Electric’s Smart Programmable Thermostat.

Older controllers also tend to cause the HVAC system to short cycle. A good sign of the system short cycling is if the set temperature and the room temperature do not match.

Higher Energy Bills

Increasing energy bills can also hint towards thermostat replacement. If the thermostat is not properly reading the temperature, the heat pump might work overtime to reach the temperature.

This can cause the system to cycle multiple times within a short period of time. Unfortunately, this increases the amount of energy used. Unnecessary energy use can lead to higher energy bills and less energy efficiency.

Many of these problems can arise from a number of factors. If you want to inspect the issues yourself, you can:

• Check the Batteries
• Check the Circuit breaker
• Check the Wiring
• Clean your Mechanical Thermostat

Check the Batteries

Most modern thermostats rely on a battery for power. Locate the batteries behind the faceplate. If the thermostat's screen still won’t turn on, you may need to replace it.

Check the Circuit Breaker

Most modern HVAC systems are connected to your breaker box. The issue could stem from the breaker being tripped. If this is the case, there is no power sent to your thermostat or the HVAC system.

Check the Wiring

There are wires that connect your HVAC system to the thermostat. These wires must be connected to an appropriate node inside the thermostat to function properly. Turn off your HVAC system and take the faceplate off to check the wires. Reconnect any wires that may have disconnected and check your furnace again.

Clean your Mechanical Thermostat

Older analog thermostats use a bi-metallic strip that expands and contracts. It is normally based on the increase or decrease of temperature. The controller can stop working if dust collects on the inside. To clean it simply pop off the faceplate and blow off the inside with a can of air duster.

If you are not sure what the problem is, we recommend hiring an HVAC technician to help solve the issues. They can assist with replacements and outline thermostat replacement costs to save money and promote energy savings.