Understanding How Thermostats Work


The majority of homeowners have one or more devices, called thermostats within their homes. A thermostat is a device that controls the heat, cooling and fan functions in the home, apartment, or other living area. There can be one or more thermostats within a living area, dependent upon how many zones have been established within the home.

Heating and cooling zones are designated sections of the home, that are controlled by one thermostat. For example the second floor, could be on one zone, and the first floor another. Or the family room could be designated as one zone, while the remainder of the home is divided into other zones.

The more zones within in a home, the more specific and custom controlled is the heating and cooling throughout the home. However, each zone will require different thermostatic equipment to control that zone, as well as mechanisms to control the heating and cooling within that zone. Although in the long run, the more zones within a living area, the more efficiently the heating and cooling system can be controlled and operated. However, the initial investment in controls and mechanical systems to allow such zoning, must be balanced with the overall efficiency gained over the life time of the HVAC installation.

Some basic information regarding thermostats as well as heating and cooling zones.

1.) A single thermostat will control a single zone within the living area. This thermostat will normally control all environmental functions within that zone, such as heating, cooling and fan control. This thermostat will monitor the existing temperature within this particular zone and control and balance the heating, cooling or air movement within that one zone.

2.) The thermostat will be connected by a thermostat wire, that is installed between the thermostats location and the controls at the ductwork, if a hot air system, or the control valves, if a hot water system. Thermostats cause either dampers to open and close in an air system, or valves in a steam or hot water system.

3.) In more sophisticated systems, the thermostats can be connected via a bluetooth connection that allows the thermostat to monitor the controls at the furnace, and or cooling systems via a wireless connection. In addition these thermostats can be controlled by smart phones via WIFI to allow remote controlling of a homes environmental systems.

4.) The thermostat is designed to monitor the temperature of the existing space, in relation with the temperature that the inhabitant controlling the environment wants. This monitoring and balancing will cause the heating or cooling to fluctuate on and off, to control the temperature of the environment, and bring it to within the range of temperature required by the inhabitants of the space.

5.) Most thermostats have a heating cycle as well as a cooling cycle. In the majority of systems, moderately priced, the system is either switched to cooling for summer time use, and heating for winter time use. There are more sophisticated, custom systems, that will fluctuate between the heating and cooling modes, without the flip of a switch, however, these are normally not installed in the average home and are more expensive and sophisticated in nature.

6.) The environmental heat or cooling is not controlled by the fluctuation of the temperature of the air or water that is flowing through the ducts or the piping. The temperature is controlled by the length of time that the hot water actually flows, or the hot air is distributed. Each time the hot water or the hot air flows through the system, the thermostat will determine how long this flow will last, to reach the desired temperature.

7.) The thermostat wiring is normally a ( 5 ) conductor, light gauge wire, that is low voltage. Low voltage means that the actual current is probably less than 12 volts, and is not what is called line voltage, which is normally 120 volts in the residential home. The thermostat wiring is normally connected to a transformer, that converts the line voltage to the direct 12 volt current needed for the thermostats to function. Therefore, the low voltage of the thermostat wiring allows this wiring to run throughout the home without as much concern for electrical safety as if the wire was 120 volts.

8.) There are several different types of thermostats that are commonly used in the residential market. Each of the thermostat types will perform the same functions, turn the heat and cooling or the fan on and off. However, as the level of sophistication increases by offering different levels of control, as well as programming and scheduling options, the expense of the thermostat increases as well as the installation equipment and labor.

9.) In the past, the typical round wall mounted thermostat, would simply turn the systems on and off, and measure the temperature of the environment. There would be a balancing system controlled by a mercury bubble that would allow the thermostat to monitor the existing temperature, and turn on and off to control the environment. Today’s sophisticated thermostats can be programmed to turn on and off at different times of the day, set temperatures at different levels, as well as decipher the difference of weekday heating and cooling requirements, verses, weekend needs. The sophistication is now almost limitless and the scheduling and monitoring of heating and cooling systems has advanced to almost total control of your environment.

10.) Thermostats are now provided with blue tooth capability, to allow the user to control the thermostat settings from their smart phone, from anywhere in the country. This ability to control and monitor the systems is a handy situation, especially in areas of the country where the accurate temperature and environmental monitoring is important to fuel consumption, as well as proper maintenance of the home.

Although replacement of thermostats, as well as the maintenance of the control systems, are normally very easily performed by the homeowner, there are special tools and monitoring equipment that allow the professional to properly adjust, trouble shoot, and fix systems that develop issues, due to temperature control and monitoring.

The thermostat is a major element of your heating and cooling systems, and is paramount in importance to properly and efficiently manage the fuel consumption of your home. If you are willing to take the time and effort to properly regulate your homes environment through these sophisticated thermostats, the savings in oil, gas and electricity can be substantial.

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