Introduction to heating

Annual Fuel Utilization Efficiency (AFUE)

An indication of how well a furnace converts energy into usable heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

Atomize

The process by which a liquid is converted into a fine spray

Combustion

The process by which a fuel is a ignited in the presence of oxygen

Condensing furnace

A furnace that contains a secondary heat exchanger that extracts latent heat by condensing exhaust (flue) gasses

Electrode

An electrical terminal that will conduct a current

Flame rectification

The process by which a flame produces a sensible electrical current

Heat exchanger

A device, usually metal, that is used to transfer heat from a warm surface or substance to a cooler surface or substance

Hot surface igniter

A ceramic device that glows when an electrical current flows through it. Used to ignite gas in a gas furnace

Induced-draft furnace

A furnace in which a motor-driven fan draws air from the surrounding area or from outdoors to support combustion

Infiltration

Air that enters a building through doors, windows, and cracks in the construction

Manometer

An instrument that measures air or gas pressure by the displacement of a column of liquid

Natural-draft furnace

A furnace in which the natural flow of air from around the furnace provides the air to support combustion

Oil burner

The main component of an oil-fired furnace. It combines oil and air and sprays the combination into the combustion chamber

Orifice

A precisely drilled hole that controls the flow of gas to the burners

Piezoelectric

The property of a quartz crystal that causes it to vibrate when a high-frequency voltage is applied to it

Primary air

Air that is pulled or propelled into combustion process along with the fuel

Redundant gas valve

A gas control containing two gas valves in series. If one fails, the other is available to shut off the gas when needed

Relative humidity

The amount of moisture in the air in relation to the capacity of the air to hold moisture

Safety pilot

A pilot light with a flame-sensing element

Secondary air

Air that is added to the mix of fuel and primary air during combustion

Standing pilot

A gas pilot that is on continuously

Spud

A threaded metal device that screws into a gas manifold. It contains the orifice that meters gas to the burners

Thermocouple

A device made up of two unlike metals that generates electricity when there is a difference in temperature from one end to the other

Vaporized-type oil burners

Grade # 1 oil is used for

Pressure-type oil burners

Grade #2 oil is used for

Round chambers

70 to 90 degrees

Long chambers

30 to 60 degrees

A gas-fired warm air furnace heats by

Conduction

If you burn your finger by touching a hot surface, it is an example of

Convection

A gas burner flame should be

Blue with an orange flame

A oil burner flame should be

Yellow

Butane

Has the highest heating value

Flows over the heat exchangers

In a forced-air furnace, air

Extracts heat by condensing the flue gas that flows through the heat exchangers

In a condensing furnace, the condensing heat exchanger

Humidifiers

Add moisture to the air

Low-pressure gun type

Pressures from 1 to 15 psi

High-pressure gun type

Pressures up to 100 psi

Single-stage oil pump

Is used where the oil supply is above the burner and oil is fed by gravity

Two-stage oil pump

Used where the storage tank is below the burner

Nozzle assembly

Consists of Oil feed line, the Nozzle, Ignition electrodes, and the transformer connections

Power assembly of a high-pressure burner

Motor, fan, and oil pump