Hero Words: What Do Heating and Air Words Mean?

What is heat?

Heat is energy that moves from something warmer to something cooler. When you hold a cup of cocoa, heat moves from the cup into your hands.

What is thermal energy?

Everything is made of tiny bits called particles, and they are always jiggling. Thermal energy is the energy of all that jiggling. Hot things jiggle fast. Cool things jiggle slower.

What is temperature?

Temperature tells how hot or cold something is. It is a number that shows how fast the tiny particles are jiggling.

You’ve seen it when: the weather report says “98 degrees today”.

What is a degree?

A degree is one step on a temperature scale, like one step on a ladder. In the United States we mostly use degrees Fahrenheit. Scientists often use degrees Celsius.

What is a thermometer?

A thermometer is a tool that measures temperature. Some have a red or silver line that climbs up when it is warm. Some show the number on a little screen.

You’ve seen it when: a grown-up checks the temperature in the fridge or on the weather app.

What is cold?

Cold is not a thing of its own. It is what we call it when something has less heat. You can’t pour cold into a room. You can only take heat out.

What is conduction?

Conduction is heat moving by touch. When a metal spoon sits in hot soup, heat travels up the spoon to the handle.

You’ve seen it when: a seatbelt buckle feels hot after the car sits in the sun.

What is convection?

Convection is heat moving by riding along with air or water. Warm air spreads out, gets lighter and floats up. Cooler air sinks and takes its place.

You’ve seen it when: an upstairs room is warmer than downstairs. Try the Hot Air Rises lab.

What is radiation (heat you feel from far away)?

Some heat travels through the air as invisible rays, without touching anything. That is how sunshine warms your face. Scientists call it radiation.

You’ve seen it when: you step from shade into sun and feel warmer right away.

What is an insulator?

An insulator is a material that slows heat down. Foam, wool and fluffy stuff with lots of trapped air are good insulators.

You’ve seen it when: a foam cooler keeps ice frozen at the park. See the Keep It Cold lab.

What is a conductor?

A conductor is a material that lets heat move through it easily. Most metals are good conductors. That is why air conditioner coils are made of metal.

What is insulation?

Insulation is fluffy or foamy stuff in the walls and attic of a house. It works like a big winter coat for your home, slowing heat from getting in or out.

What is energy?

Energy is what makes things move, light up, heat up or change. Food gives you energy. Electricity gives machines energy.

What is water vapor?

Water vapor is water as an invisible gas floating in the air. You can’t see it, but it is almost always there.

You’ve seen it when: actually, you haven’t! The white cloud above a hot bath is tiny drops. The vapor itself is invisible.

What is humidity?

Humidity is how much water vapor is in the air. High humidity feels sticky and muggy. Low humidity feels dry.

You’ve seen it when: a summer morning in Austin feels damp, like walking into a bathroom after a shower.

What is condensation?

Condensation is when water vapor in the air touches something cold and turns back into tiny drops of liquid water.

You’ve seen it when: a glass of ice water “sweats” on a hot day. Try Cloud in a Glass.

What is evaporation?

Evaporation is when liquid water turns into invisible water vapor and floats away into the air. It takes heat with it when it goes, which is why it feels cooling.

You’ve seen it when: a puddle disappears on a sunny day, or wet hands feel cool in front of a fan. Try the Cool by Evaporation lab.

What is dew?

Dew is water drops that form on grass, cars and spider webs overnight. The ground and grass cool down at night, and water vapor condenses on them.

What is the dew point?

The dew point is the temperature where the air is so full of water vapor that drops start to form. If something is colder than the dew point, it gets wet with condensation.

What is frost?

Frost is ice that forms on cold things when water vapor freezes right onto them. It looks like white fuzz or tiny crystals.

What is a drain line?

A drain line is a pipe that carries away the water an air conditioner collects. It often ends outside near the house, where you may see it drip in summer.

What is a drain pan?

A drain pan is a tray under the indoor coil. It catches the drips of condensation and sends them into the drain line.

What is air?

Air is a mix of invisible gases all around us. You can’t see it, but you can feel it move when the wind blows.

What is airflow?

Airflow is air moving from one place to another. A heater or air conditioner needs good airflow, or it can’t move heat well.

What is air pressure?

Air pressure is air pushing on everything around it. Air moves from places where it is pushing harder to places where it is pushing less. That is what makes wind, and it is what pulls air into a return vent.

What is a fan?

A fan is spinning blades that push air. A ceiling fan makes you feel cooler by blowing air across your skin, but it does not make the room colder.

You’ve seen it when: you feel cooler under a fan, even though the thermometer stays the same.

What is ventilation?

Ventilation means bringing outside air in and letting inside air out. A bathroom fan that pulls steam out after a shower is ventilation.

What is a draft?

A draft is a little stream of air sneaking in or out where it shouldn’t, like around a door or a window.

You’ve seen it when: the curtain moves a little by a closed window on a windy day.

What is dust?

Dust is a mix of tiny bits: lint from clothes, fur, dirt from shoes and crumbs too small to see one by one. Dust floats in the air and settles on things.

Want to find it? Try the Dust Detective lab.

What is static electricity?

Static electricity is a tiny electric charge that builds up when things rub together. It is stronger when the air is dry, which is why you get more little zaps in winter.

See it in the Static Balloon lab.

What does HVAC mean?

HVAC stands for Heating, Ventilation and Air Conditioning. It is the name for all the machines that keep your house warm, cool and comfy.

What is an air conditioner?

An air conditioner is a machine that moves heat from inside your house to outside. The air left inside feels cooler. It also pulls water out of the air.

Read more: How does an air conditioner work?

What is refrigerant?

Refrigerant is a special liquid that runs in a closed loop of pipes in an air conditioner or heat pump. It picks up heat inside and lets it go outside. Only trained technicians handle refrigerant.

What is a compressor?

A compressor is a strong pump in the outside unit. It squeezes the refrigerant, which makes it hot so it can give off heat outside. It is the hum you hear from the outside unit.

What is a coil?

A coil is a set of metal tubes with thin metal fins around them. Refrigerant flows inside the tubes. Air flows across the fins. Heat moves between them.

What is an evaporator coil?

The evaporator coil is the cold coil inside your house. Refrigerant boils inside it and soaks up heat from the air.

What is a condenser coil?

The condenser coil is the coil in the outside unit. It lets go of the heat that came from inside your house.

What are fins?

Fins are the rows of very thin metal sheets on a coil. They give the air lots of metal to touch, so more heat can move. They bend easily, so only technicians clean them.

What is the outdoor unit?

The outdoor unit is the big metal box outside with a fan on top. It holds the compressor and the condenser coil. Leave it to the grown-ups and technicians.

What is an air handler?

The air handler is the indoor cabinet that holds the blower fan and often the indoor coil. In many Austin homes it lives in the attic, a closet or the garage.

What is a blower?

The blower is the big fan inside the air handler or furnace. It pulls air in through the return and pushes it out through the ducts to your rooms.

What is an air filter?

An air filter is a frame with a soft screen that catches dust, fur and lint before they reach the machine. It is like a doormat for the air. Grown-ups change it.

What are ducts?

Ducts are the tubes and metal boxes that carry air from the machine to every room. They are the hallways for air, hidden in the attic, walls or floors.

What is a return vent?

A return vent is the big air grille, usually on a wall or ceiling in a hallway, where the AC breathes in air to take back to the machine. It usually has no slats you can move. Keep furniture, toys and laundry away from it.

What is a supply vent?

A supply vent is where warm or cool air comes out into a room. In most Austin homes, supply vents are in the ceiling. They often have little slats that point the air.

What is a thermostat?

A thermostat is the box on the wall that feels the room’s temperature and tells the heater or air conditioner when to start and stop. Think of it as the boss of the machine.

What is a metering device?

A metering device is a tiny opening in the refrigerant loop. When refrigerant squeezes through it, the pressure drops and the refrigerant gets very cold.

What is a heat pump?

A heat pump is an air conditioner that can also run backwards. In winter it picks up heat from the outdoor air and carries it inside.

Read more: How does a heater work?

What is a reversing valve?

A reversing valve is a switch inside a heat pump that sends the refrigerant the other way, so the machine can heat instead of cool. It is like a railroad switch.

What is defrost?

Defrost is when a heat pump melts the frost off its outside coil on a cold day. You may see steam rise and hear a whoosh.

What is a furnace?

A furnace is a heater that warms air by heating a metal box. Many furnaces in Austin burn gas.

What is a heat exchanger?

A heat exchanger is the metal box inside a furnace that gets hot. Air blows across the outside of it and warms up. The flame and smoke stay inside it.

What is a flue?

A flue is the pipe that carries smoke and gases from a gas furnace or water heater up and out of the house.

What is the heat index?

The heat index is a “feels like” number. When the air is hot and humid, it feels hotter than the thermometer says, because sweat can’t dry as fast.

What is a heat dome?

A heat dome is a big area of high pressure high in the sky that sits over a place for days. It pushes air down and traps heat like a lid on a pot, so it stays hot.

What is a cold front?

A cold front is the edge of a big mass of cooler air pushing into warmer air. When it passes, the temperature can drop fast and the wind can change.

What is a blue norther?

A blue norther is a Texas name for a strong cold front that blows in from the north. The temperature can drop a lot in a short time, often with a dark blue sky behind it.

Read more on Austin Whys.

What is shade?

Shade is a spot where something blocks the sun. Shade is cooler because the sun’s rays can’t reach it directly.

See Shade Squad to learn how trees help.

What is an HVAC technician?

An HVAC technician is a trained person who checks, cleans, fixes and installs heaters and air conditioners. They use special tools and follow safety rules.

Read more: What does an HVAC technician do?

What is maintenance?

Maintenance means taking care of a machine before it breaks, like a check-up. For a heater or air conditioner, a technician looks, measures and cleans so it keeps running well.