How To Tell if My Thermostat Has Low or High Voltage?

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Thermostats are used nearly in every house as a part of the heating systems known as HVAC systems. HVAC systems have two types; the central HVAC system depends on low voltage thermostats to indirectly control the system using signals.

The other type of HVAC system is an electrical one, which depends on high voltage or line thermostats. This type of thermostat controls the system directly and the heaters, so it controls the amount of time the heater is turned on and eventually the room’s temperature. 

How To Tell if My Thermostat Has Low or High Voltage?

Determining what type of thermostat you have can be done in four ways; the first way is to know how you cool or heat your house. The second way or method is to measure the voltage of your thermostat; the third way is to know the number of wires in your thermostat.

The fourth and last method is to know the thickness of your thermostat wires. Knowing which type of thermostat you have can be useful when you want to replace your old thermostat with a smart thermostat.

  • How You Cool or Heat Your Home

The first method to follow when determining the voltage of your thermostat is to determine the HVAC system. The HVAC system tells you how you cool or heat your house; as a result, you will be able to choose a more compatible thermostat if you want to replace your old one.

HVAC systems have two types; the first type is the central HVAC system which is controlled by a thermostat of low voltage. The second type is the electric HVAC system which is either controlled by a thermostat of high voltage or another device. For example, the electric system can be controlled by IR technology like the ones found in ductless mini split heat pumps.

  • Central HVAC Systems

A Central HVAC system consists of a source for cooling or heating; a single thermostat controls this source. The main task of the thermostat is to provide AC or heat to the house’s distribution systems. Central HVAC systems can be either radiator based or ducted; the fuels used in the central systems can vary from wood, oil, and water, to gas.

If your house is operated by a central HVAC system and you found that one or two thermostats only control it, then you have a thermostat of low voltage. Central HVAC systems have many types:

      • Furnace Heating Systems
      • Forced Air Systems
      • Ducted Heat Pumps
      • Boilers
  • Electrical HVAC Systems

Electrical HVAC systems can be determined through the usage of multiple thermostats; usually, there is a thermostat for every room. In addition, these systems are fully operated using only electricity, unlike central HVAC systems, which depend on fuels like water, oil, or wood.

The high voltage electrical HVAC system has many types like in-ceiling radiant heat, fan-forced heaters, baseboard heaters, and electric in-floor heating. Another example of an electrical HVAC system is mini split heat pumps (ductless), but the difference is that IR signals control it.

This means that the system is controlled by either a smart mini thermostat or a remote instead of wiring the traditional thermostat into the wall. Therefore, if you have multiple thermostats or a thermostat for every room in your house, you have an electrical HVAC system of high voltage.

  • Measure The Voltage of Your Thermostat

To know whether you have a high or low voltage thermostat, you can use this method which is considered an easy way to know. To measure the voltage of your thermostat, you have two options to use:

  1. By checking under its label, you can check your thermostat to know if it’s a high voltage type. Most manufacturers put a label of “HIGH VOLTAGE” or the number of volts like “240V” on their thermostat to make it easier for you to know. However, some manufacturers don’t put a label on the thermostat, so you should keep that in mind. In addition, low voltage thermostats also should have a label for the voltage or a label of “LOW VOLTAGE.”
  2. The second option is to use a voltage meter to measure the voltage of your thermostat; however, the accuracy of the measurement will depend on the quality and the accuracy of the used voltage meter. The difference between a high voltage thermostat and a low voltage thermostat is huge. So if the reading is low, it’s a low voltage thermostat and vice versa.
  • The Number of Wires in The Thermostat

You can tell the type of your thermostat by looking at the number of wires going through it, but when doing this step, you will need to ensure safety first. So first, turn off your thermostat from the breaker’s circuit; this is an essential step if you are going to remove the plastic covering of the thermostat.

If you see the wires in the thermostat of multi colors and small size, this thermostat is a low voltage. You can also tell the type by looking where the wires are going if the wires are going into the dry walls through a small hole.

Meanwhile, the high voltage thermostat wires are connected to the electrical box nearby. If the wires are grouped and few in number, this means you have a high voltage thermostat. The wires should be grouped by color, for example, a group of red wires, black wires, and white wires. 

The Thickness of The Wires in the Thermostat

You can also tell the type of the thermostat by the thickness of the wires going through the thermostat if you see that the wires going through the thermostat have a wide thickness. Meanwhile, if you notice that the wires of the thermostat have a thin thickness, then this is a low voltage thermostat. 

What is The Difference Between Low and High Voltage Thermostats?

  • Low Voltage Thermostat

A thermostat of low voltage can only handle voltage between 12 to 24 volts, where they control the main HVAC source of the house. The low voltage thermostats indirectly use signals to control your home’s temperature; they can not power individual heaters. 

The thermostat works by sending a signal to the main HVAC system in the house to turn it off or on; then, the HVAC system starts to burn the fuel to heat the house. If you are living in North America, you probably have a low voltage thermostat in your house. 

  • High Voltage Thermostat

The main difference between low voltage thermostats and high voltage ones is the range of voltage they can handle. High voltage thermostats can handle a voltage from 120 to240 volts; high voltage thermostats are also known as line thermostats.

A high voltage thermostat does the opposite of allowing a voltage thermostat, which controls the house’s main electric circuit and the heaters. Instead, the high voltage thermostat works by controlling the amount of time the heater is turned on, so it controls the temperature of the room. 

Conclusion

To sum up, if you plan to upgrade to a smart thermostat, you should know which type of thermostat you have at your house. This will make it easier for you to find a compatible thermostat; if you live in North America, you probably have a low voltage thermostat in your house.

Other regions use electrical systems that depend on high voltage or line thermostats; you can also have multiple types of thermostats at your home. Therefore, it’s better to determine your thermostat type before upgrading to another type. 

You can tell the type of thermostat your house is using by using four methods,

  1. The first way is to know how you cool or heat your house.
  2. The second way or method is to measure the voltage of your thermostat.
  3. The third way is to know the number of wires in your thermostat.
  4. The fourth and last method is to know the thickness of your thermostat wires.

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