Why Is House Thermostat Reading the Wrong Temperature?

A thermostat simply won’t be able to keep your home at a comfortable temperature, if its readings are incorrect.

The device might start reading the wrong temperature, in case its batteries are dying, the inside of the thermostat is dirty, or the temperature sensor had failed. Thermostats that are located close to drafts, heating sources, and in direct sunlight also won’t be able to sense the right temperature.

Why Is House Thermostat Reading the Wrong Temperature?

Bad location

If the thermostat has been installed near heat sources or drafts, it won’t be able to read the correct temperature.

Dying batteries

The thermostat might fail to work effectively if its batteries are about to die. Replace them and see, if this solves the problem.

Wrong settings

Make sure that the thermostat is set to either ‘cool’ or ‘heat’ and that the fan is not on.

Dirty thermostat

If the device is covered in dust, it might fail to correctly read the temperature.

Clogged air filter

A dirty filter affects the HVAC system’s ability to cool or heat. In such a case, it’s not the thermostat that’s reading the wrong temperature, it’s the HVAC unit that’s failing to deliver.

Failed temperature sensor

If the sensor is dirty or improperly calibrated, then it won’t be able to read the temperature correctly. The element might also, at one point, simply go bad.

Unlevel thermostat

Nowadays, such issues are quite rare, but if you have an old mercury thermostat, then you would have to make sure that the device is level.  

Read: Temperature Thermostat Problems

Why Is My Thermostat Reading Higher Than Setting?

  • Issues with the wiring can cause too much heat in and around the thermostat
  • The thermostat is placed in an area with a high temperature (in direct sunlight, for example)
  • The HVAC system is of the wrong size for your house and it’s unable to reach the setting
  • You have a large house with only one thermostat and it can’t keep the temperature consistent throughout your home
  • It’s a very hot day and your air conditioner is unable to bring the indoor temperature any lower

Read: Benefits Of A Programmable Thermostat

Why Is My Thermostat Reading Lower Than Setting?

  • The outdoor unit is covered in ice
  • It’s way too cold outside
  • Your furnace is too small for your house
  • Your house doesn’t have proper insulation
  • There are leaky ducts
  • The thermostat is located in a drafty area

Nest Thermostat Not Reading Correct Temperature

A Google Nest thermostat will often show you different temperatures on the screen

The temperature in the middle is the one that the device has been set to and the small temperature at the edge is the temperature in your house right now.

So, you might be simply looking at the wrong temperature.

White Rodgers Thermostat Wrong Temperature

  1. Make sure that the wires are not loose.
  2. Reset the thermostat by pushing the up and down buttons.
  3. Set the system to ‘cool’ and lower the set temperature below room temperature. If the thermostat clicks in about 5 minutes, then it’s operating correctly.

Why Is My Honeywell Thermostat Not Reading Temperature Correctly?

If you have the kind of thermostat that can be opened, you can try using canned air to gently clean the inside of the device.

Read: Thermostat Wire Color Code

How Do I Know If My Thermostat Is Reading the Correct Temperature?

Here is an easy DIY method to find out, if your thermostat is reading the correct temperature:

  1. Tape a paper towel to the wall right next to the thermostat.
  2. Tape an ordinary thermometer over the towel and leave it there for around 15 minutes.
  3. Compare both of the temperatures.

How Do You Check If a Thermostat Is Working?

If you feel comfortable working with wires, you can try bypassing the thermostat to find out, if the thermostat is the thing that is causing the problem or not.

How Do I Calibrate My Thermostat Temperature?

To calibrate a programmable thermostat, you would have to:

  • Determine the temperature difference.
  • Access the calibration settings – check your thermostat’s manual to find out how you can access the right menu.
  • Press the arrows to adjust the temperature change.
  • Go back to the main screen and check if the calibration worked (you can tape a thermometer to the wall to find that out).

Where Is the Temperature Sensor for a Thermostat?

A lot of thermostats use a thermistor – an element that changes its resistance whenever there is a temperature fluctuation. These thermistors are usually put in the electronics of the actual thermostat

Where Is House Temperature Sensor?

Temperature sensors are generally located inside the thermostat. That’s why it is incredibly important to find the right location for your device.

However, Google Nest, for example, allows you to install temperature sensors in a different location than that of the thermostat. 

You can place the sensor in a room without the thermostat. The sensor will measure the temperature in that particular room and then send the information to the thermostat.

Some temperature sensors are also placed near evaporator coils inside an air conditioning unit.

Thermostat Temperature Sensor Not Working

Each thermostat has its own sensor. Mechanical devices have bimetal strips, digital thermostats use thermistors, and smart thermostats usually have remote-controlled sensors that can be controlled via apps and Wi-Fi.

Cleaning the temperature sensor might sometimes do the trick. However, if the sensor had gone bad, then the chances are high that you would have to get the whole thermostat replaced.

How Do You Make a Thermostat Think It’s Hotter?

You would have to raise the temperature next to the thermostat.

For example, you can use a microwaved heating pad and put it next to the device for a few minutes. The thermostat will sense the temperature change and will make the air conditioner kick in.

You can also try putting a warm stocking cap over the thermostat.

How Do You Make Thermostat Think It’s Colder?

Wrap the thermostat in insulation with a frozen cold pack. You can also tape a cup full of ice below the device.

Read: No Power To The Home Temperature Thermostat – Troubleshooting Guide

Why Is My House Different Temperatures?

Here are the most common reasons for these temperature swings:

Multiple floors

The temperature on the upper floors is naturally higher as heat rises and cool air ‘falls’.

Distance from the HVAC system

The farther the room is from the system, the cooler or hotter it will get.

A wrong-sized unit

A system that is too small might not be able to reach the desired temperature, while a unit that is too large will shut down very fast – the heated or cooled air simply won’t have enough time to reach all the floors or rooms.

Poor insulation

The rooms that are not properly insulated can’t be heated up or cooled down as effectively.

Closed vents

The cool and warm air might be making it to the vent, but it won’t be able to enter the room, if the vent is blocked by furniture, for example.

Poor airflow

The better the airflow in the house, the more even the temperature. You can use fans to help the HVAC system circulate the air. 

Read: HVAC Thermostat Problems

Why Is One Room in My House Warmer Than the Rest?

  • The room is on the sunny side and it has a lot of windows
  • The ductwork in this part of the house is clogged
  • The return air vents in the room are damaged or blocked
  • The room is poorly insulated

How Do I Fix Uneven Cooling in My House?

  1. Make sure that the air vents are not blocked and that they are clean.
  2. Switch the fan to ‘on’ so that it helps circulate the cooled air around the house even when the AC is turned off.
  3. Check the ducts for leaks.
  4. Properly insulate your attic.
  5. Invest in a zoning system that will allow you to have more control over the temperature in individual zones.