DEPARTMENT OF CHEMICAL ENGINEERING
Submitted BY
Krishna Kant Nayak
Student MNIT Jaipur

Economiser E20 electric heating

 Introduction
 History
 Construction
o Mechanical thermostat
o Electrical thermostat
 Working Principle
 Switches on and off process
 Types of thermostat
 Application
 Advantage and Disadvantages
 Reference

A thermostat is a temperature sensor that is found in
many common electrical devices, such as ovens, heaters,
refrigerators and air conditioners and boilers.
A thermostat is a component which senses
the temperature of a system so that the system's
temperature is maintained near a desired set point.

 The first electric room thermostat was invented in 1883 by
Warren S. Johnson of Wisconsin.
 Albert Butz invented the electric thermostat and patented it in
1886.
 One of the first industrial uses of thermostat was in the
regulation of the temperature in poultry incubators.

MECHANICAL THERMOSTAT
A mechanical thermostat has two main parts: a temperature sensor
and an electric switch. The mechanical sensor is a material (or a gas
inside a tube) whose area (or volume) changes as the temperature
changes. This sensor is placed in contact with the object of interest
(an open space in the room or the refrigerator, etc). Expansion of the
material causes the detector to curl (because of its construction or
because it is made of two metal strips with different expansion
coefficients) or press on a diaphragm (with a spring mechanism),
thus closing or opening an electric circuit.

 In an electrical thermostat, the detector is made of material whose
electrical resistance depends on the temperature. The strength of the
current flowing through this detector is translated into an exact
temperature. Set points are established for the circuit (depending on the
temperature) to turn an accompanying device on or off, as desired. An
electronic thermostat is much more accurate than a mechanical one, and it
can also measure the temperature accurately and display it at all times (as
opposed to a mechanical thermostat, which does not have a value for the
current temperature and only "knows" whether it is higher than the set
point or not).

 Thermostat basically works on the principle of thermal
expansion of solid material and that is solid material
changes its shape area and volume in responce to the
change in temperature

How a bimetallic thermostat switches on and off
 An outer dial enables you to set the temperature at which the
thermostat switches on and off.
 The dial is connected through a circuit to the temperature sensor,
which switches an electrical circuit on and off by bending more or
less.
 Iron expands less than brass as it gets hotter, so the bimetal strip
curves inward as the temperature rises.
 The bimetal strip forms part of an electrical circuit . When the strip
is cool, it's straight, so it acts as a bridge through which electricity
can flow. The circuit is on and so is the heating. When the strip is
hotter, it bends and breaks the circuit, so no electricity can flow.
Now the circuit is off.

 they are categorized into two basic types:
 1. Line-voltage thermostats
 2. Low-voltage thermostats
 1. Line voltage thermostats are used in single heating systems like
baseboards and radiant systems.
 2. Low voltage thermostats are perhaps more efficient in controlling the
flow of electric current. A low voltage thermostat helps you to precisely
control current

 Thermostats are used to monitor and regulate the temperature of
an indoor area.
 By using the thermostats we can operate different types of
temperatures by regulating the cooling and heating.
 thermostats are used to protect the circuits from the excess of
current.
 thermostats are used in the cooling system of car.

 Energy savings
 Create revenues by providing an
opportunity for creating and selling apps
and services that can be used with smart
thermostats .
 Reduce energy companies’ installation &
production costs
 Improve the quality of
customers’/managers’ lives—–The smart
thermostats help them to cut their bills by
20% .

 It is a mechanical device and can break or go off calibration.
 It is subject to human interference and people setting it too low
or high depending on their preference.
 If there is a lack of proper use, then the smart thermostats are not
considered as energy-saving.
 Does not take into consideration the humidity in the air or the
velocity of the air which can also effect the apparent skin
temperature.

 https://en.wikipedia.org/wiki/Thermostat
 http://www.explainthatstuff.com/thermostats.html
 http://www.temperatures.com/bimet.html
 http://smartthermostatguide.com/8-smart-thermostat-
advantages/
 http://www.airrepairpros.com/customer-
education/advantages-of-a-programmable-thermostat/

THANK YOU