unit c - section 3.2-3.3 -- heating system technology
TRANSCRIPT
HEATING SYSTEM TECHNOLOGY&
HEAT LOSS/INSULATION
Mr. Ilko
IN OUR LIVES
We require many different heating technologies to make sure our lives stay warm and cozy
Some of the first were blankets, coats, hats, etc
Now we rely on our machines to provide an even more comfortable environment (i.e furnace)
HOW WE STAY WARM
All rooms do not have furnaces inside them to heat the rooms so we need to have a way to move heat around
We also need ways that will prevent our furnaces from turning on when we don’t need them, but turn on during chilly days
(i.e Summer time)
THERMOSTATS
The most common way we can control the heat in our house is through a device called a thermostats
Room temperature or 20○C is the most common setting for us in our houses, offices or schools.
Thermostats control the level of the heat in the building its set up in Thermostat means “thermo” –heat, “stat” – means
to keep stable
THERMOSTAT CONT…
We don’t only use thermostats to maintain temperature of the rooms in a building They are also used to adjust the
temperature of certain electrical devices ( oven or air conditioner)
HOW IT WORKS?
Inside of a thermostat the is a bimetallic strip that consists of two different metals
When heated one of the metals will expand faster than the other. This causes the strip to bend
The bending of the bimetallic strip is used to measure the temperature change
As the strip bends and unbends it opens and closes electrical circuits that also control the heat-regulation devices
HEATING SYSTEMS
There are two main types of systems: Local heating system Central heating system
Both contribute in different ways and both have their own disadvantages
LOCAL HEATING SYSTEM
Provides heat for only one room or a small part of a building
Common examples of this type of heating system are; Fireplaces Wood-burning stoves Portable space heaters
CENTRAL HEATING SYSTEM
Provides heat from a single, central source (furnace)
Heat transfers through a network of pipes, ducts, vents or other openings throughout the building
Most of the newer homes have forced air heating, the older ones have hot water heating
DEFINITIONS
Find the following definitions at the back of your book Forced air heating-
Hot-water heating-
IN ORDER FOR ALL THIS TO WORK THE PROCESS OF CONVECTION WORKS CONSTANTLY
It moves all of the warm air around the room keeping the temperature warm
KEEPING COOL
Similar to producing heat in we also try to keep cold in, in certain situations (freezer)
We commonly use cooling systems to remove heat from a room or other enclosed space. The basic parts are; a storage tank, a compressor, a
freezer unit, condenser coils and a refrigerant.
The refrigerant (liquid) used in a refrigerator evaporates at a very low temperature. This creates freezing temperatures inside the fridge
INSULATION
Used to limit heat loss to the outside environment or to limit the amount of heat that is able to enter a cooler building on a hot day
Because heat only travels one direction (high to low), insulation is good for both cases.
MATERIALS IN BUILDING
When you are building a home you want to pick things that will be good insulators not conductors
You don’t want materials that will allow easy transfer of heat in and out of the house to easily
The thermal conductivity of a material reflects its ability to transfer heat by conduction. Eg. Bricks, fiber glass, Styrofoam, stone, etc
HEAT LOSS
Contractors commonly use infrared photography to check for areas of heat loss in a building. Its called the thermogram
Colour represents the type of heat loss The roof, windows, doors and walls are the main
problem areas
The problem with this is that we need more heat to compensate for this, so we create more waste to keep warm.
R-VALUE
Every insulator is given a number called an R-Value
The higher the R-Value, the better the product is at providing insulation.