Transcript Air Conditioners and Heaters - Clinton Public School District

HVAC GENERAL FACTS
• In most homes, we use an HVAC system to heat and
cool the air.
• HVAC stands for Heating, Ventilation, and Air
Conditioning
• While HVAC systems come in many forms, the most
common is called a Split-System AC unit.
CONTROL
• HVAC systems are controlled by a
THERMOSTAT.
• The thermostat is set to a specific
temperature (Ex: 72) and a tolerance (Ex: 3).
• If the temperature rises above or below the
tolerance (So above 75 or below 69) then the
HVAC system turns on to correct it.
EVAPORATION AND CONDENSATION
• All HVAC system utilize evaporation and
condensation in order to heat and cool the
air.
• Evaporation occurs when a liquid turns into a
gas. (Like water boiling)
• Condensation occurs when a gas turns back
into a liquid. (Like a cold glass of water
sweating)
EVAPORATION AND CONDENSATION
• In order for a liquid to evaporate it must
absorb heat.
• In order for a gas to condensate it must
release heat.
• That is why a liquid like alcohol feels cold on
your arm. It absorbs heat from your arm to
evaporate.
FREON
• Air conditioners utilize this fact to cool and
heat homes.
• A liquid called Freon is inside of your air
conditioners.
• Freon has a boiling temperature of around 25°C.
HVAC
• In HVAC systems, we allow Freon to evaporate
and condensate in order to heat and cool
homes.
• When the Freon evaporates, it provides cold
air.
• When the Freon condenses, it provides warm
air.
When the gas evaporates
it COOLS the metal pipes.
AIR CONDITIONER
It then moves to the
• An HVAC system is
compressor that
called an air
compresses it A LOT.
conditioner when it
is used to cool an
Whichenvironment.
makes it _________.
Freon begins as a
liquid at the
expansion valve.
The expansion valve
allows the liquid to
expand and turn into
a gas.
AC SYSTEMS
The liquid is now back to the expansion
valve that removes the high pressure
and allows it to evaporate back into a
gas again.
But the liquid is still under
too high of pressure to
evaporate again.
Cooling off the gas allows it
to turn back into a liquid.
The HOT, high pressure gas
is then sent to the
condenser where cold air
cools down gas.
HEAT PUMP
• In the winter, we can run
that AC system in
reverse.
• In reverse, it is called a
heat pump.
• Now we run the pump in
reverse which makes the
blue region red and the
red region blue.
HEAT PUMPS
• Heat pumps are only effective to certain
temperatures (each is different).
• Unfortunately that temperature is often
higher than the coldest nights.
• Therefore, we have to use heating coils or
furnaces in addition to heat pumps.
HEAT PUMP
• A heat pump essentially heats the air in your
home by air conditioning the air outside.
• In the same way that an air conditioner cools
your home by heating the air outside.
OR
INSULATION
• Insulation is therefore an
INTEGRAL part of a home.
• If too much heat is allows
to flow through the walls
of the home (either in or
out) then the HVAC system
will have to work harder.