Thermostats use a bimetallic strip that bends when heated to open and close electric circuits that control heating systems. Thermostats can regulate local heating systems that provide heat to a single room directly, or central heating systems that gather heat in one area and distribute it throughout a building through forced air ducts, radiators, or other means. Central systems include forced air heating, which uses a furnace and ducts, and hot water heating, which uses a boiler to heat water circulated through radiators.
2. Thermostats
• "Thermo" = heat "stat" = maintain or keep the
same
• In order to control or regulate the temperature of
a room or house, we need a thermostat.
3. Thermostats
• When heated, one metal expands
faster than the other, causing it to
bend.
• The bending is used to measure
temperature change.
• When the strip bends/unbends,
it opens/closes an electric circuit
that controls the device.
5. Local vs Central Heating Systems
• Thermostats can control two different heating systems:
• Local Heating System Central Heating System
6. Local Heating Systems
• -Provide heat for one room or
small area.
• -Relies on convection to
transport the heat.
• -Ex. Fireplaces, wood-
burning stoves, space heaters,
etc
7. Central Heating Systems
• -Heat is gathered in one area, then
transported throughout the
building/system.
• -Transfer is through vents, pipes,
ducts, etc.
• - Two kinds of central heating
systems are through forced-air
heating or hot-water heating.
8. Forced Air Heating
• Air is heated in a furnace.
• Air travels through ducts and into
other rooms.
• Convection transports heat once
it exits ducts
9. Hot Water Heating
• Water is heated in a furnace/boiler.
• Pumps push water through radiators
in the house.
• Hot air travels from the radiator
through convection.
• Cold water returns to the boiler.
