Common Causes for Inaccurate Thermostat Readings
A thermostat is integral to your home HVAC systems. You rely on thermostat accuracy to stay cozy and safe and maintain optimal energy efficiency. Inaccurate readings can cause heating and cooling costs to skyrocket while making your home less comfortable and convenient. Let’s explore reasons your thermostat may give imprecise readings.
Old Age or Bad Thermal Sensor
While analog thermostats can last 30 years or even more, that isn’t typical with modern digital solutions. Modern thermostats use thermistors to read the temperature. While extremely accurate, thermistors are sensitive components with an average lifespan of about 10 years. Oxidation, heat, and humidity are factors that contribute to their failure. Some may last longer. Others may not last as long either through mishandling or manufacturing defects. When a thermistor goes bad, it usually won’t fail outright but rather be off in its sensing. If accuracy is off by more than 0.2 degrees Celsius, it’s a sign the thermistor needs adjustment or has gone bad.
Suboptimal Installation Location
Some of the latest smart thermostats support multiple remote temperature sensors. One of the advantages of that approach is that the installation location of the main unit is unimportant. That isn’t the case with a traditional thermostat, which has all components in a single package. Ideally, you should have such a thermostat centrally located within a home.
If a thermostat doesn’t have a central location, it can give misleading readings despite being technically accurate. A thermostat that’s too close to a kitchen, for instance, may read higher when the oven is on. That could cause your air conditioner to cycle on and off more often than it should. Even sunlight through a window can cause a thermostat to read inaccurately.
Dust Accumulation
Thermostats can build up dust over time under the faceplate, and that accumulation can lead to inaccuracy. Dust can accumulate on the thermistor itself and interfere with the sensing. Another common issue is that dust builds up on the contacts. Those contacts are switches through which the thermostat turns the system on and off. If they’re dirty, the system can operate as if the temperature is different from what you’re seeing on the display.
If you schedule regular HVAC maintenance, your technician will clean your thermostat each season. You can also do it yourself by removing the faceplate and using rubbing alcohol or compressed air. The temperature sensor should have a label that reads “thermistor” or “sensor.” To remove dust from between contacts, use a hard edge, such as an old credit card.
Miscalibration: Modern Thermostats
Modern thermostats can account for thermistor inaccuracies through calibration. Many units have a calibration mode that you can run and which will set the correct parameters automatically. Some also have user-defined offsets. These let you adjust the reading that you see and which the unit uses to cycle the equipment on and off. Generally, it’s best to let a skilled technician set the offsets for you. Homeowners often don’t have the sensitive equipment needed to make these adjustments accurately.
Miscalibration: Analog Thermostats
Analog thermostats don’t have a thermistor but instead employ a glass capsule filled with mercury. Such thermostats are inherently less accurate than their modern counterparts, and you should consider upgrading. Still, you can dial them in for a more accurate reading. Often, there’s a small screw. Turning it clockwise will increase the temperature reading while turning it counterclockwise will decrease it. It’s also important to test the balance of the thermostat using a level. If the unit is not level, you’ll get an inaccurate reading. That’s because the mercury switch has to be as close to horizontal as possible to work properly.
Faulty Wiring or Electrical Connections
The wiring and connections between the thermostat and electrical system generally don’t experience much deterioration within a 10-year period. Still, if they do, the electrical fluctuations can lead to inaccurate readings. High humidity is one example of where this can occur because the excess moisture results in corrosion.
Local Thermostat Services in Windsor
Guaranteed Comfort Heating & Cooling is an HVAC company located in Windsor, ON. We’re a small business with decades of experience meeting the comfort needs of area homeowners. We offer a wide selection of programmable and smart thermostats from the top brands. Certified and licensed HVAC technicians complete all our thermostat installations and repairs for heating and maintenance for cooling systems. We can handle your indoor air quality problems, too. We also back all our thermostat services with a workmanship warranty. To schedule an inspection of your thermostat, call us today, or schedule your appointment online through our website.