Thermostat

Thermostat used to control an home's air conditioning system.

A thermostat is a sensor that keeps a heating system near to a desired temperature or setpoint. It is a control system.

The thermostat works by switching heating or cooling devices on or off. This is what happens in a central heating system or an air conditioner. In some systems, it works by switching a 'heat transfer fluid' off or on as needed to keep the set temperature. The name is derived from the Greek words thermos "hot" and statos "a standing".

The simplest kind of thermostat is a bimetal strip which bends as the temperature rises, and at a set point breaks the circuit of an electrical current. Kitchen toasters use this kind of thermostat.

Because they control a system, thermostats are examples of feedback devices that maintain a steady local environment against temperature changes outside the outside world. In cybernetics, the thermostat is an example of a machine that uses feedback to maintain the stability of a heating system.

Thermostats can be either line voltage or low voltage thermostats. Line voltage thermostats have regular 120 volt power going to them and low voltage thermostats have 24 volts powering them from a transformer.

Thermostat Media

• 

  PECO T8532 Thermostat with 365 Day Programmable Calendar

• 

  Honeywell's "The Round" model T87 thermostat, one of which is in the collection of the Smithsonian.

• 

  A Honeywell electronic thermostat in a retail store

• 

  Internal combustion piston engine thermostat.

• 

  Bimetallic thermostat for buildings.

• 

  Millivolt thermostat mechanism

• 

  Residential digital thermostat

• 

  Lux Products' Model TX9000TS Touch Screen Thermostat.

• 

  Lux Products WIN100 Heating & Cooling Programmable Outlet Thermostat shown with control door closed and open.

• Armed with a pair of wire cutters Bill shows how a common thermostat reveals how good industrial designers keep track of the dimensions of a human being.*Transcript: That thermostat is one of the greatest engineering designs of last cenutry.*I know it seems such a mundane thing, but it features the single most important element of good design: It reflects us!*Look at how perfectly it fits the human hand .... This was no accident.