A – Coil
The A – Coil is a heat exchanger that is dependent on 2 coils which are first diagonally placed and then joined in the midsection which gives them a shape like ‘A’.

An electric current that shifts from one direction of flow to another very quickly.

AC or DC
Abbreviations for Alternating Current and Direct Current. They are used to represent the types of electrical circuit system.

Stands for Air Conditioning Contractors of America.

Derived from “acoustic”. An acoustical system means it creates sounds well.

An annual evaluation of how efficient the fuel to energy conversion of a furnace is. AFUE with a high rating means an efficient furnace. Our technicians can conduct AFUE tests.

Stands for American Gas Association, Inc.

Air Cleaner/Air Filter
An appliance to remove dust, debris and air particles. It catches the particles when air passes through the cleaner.

Air Conditioner
An equipment that controls the ventilation, temperature and humidity of the air inside a house. Usually kept outside the house.

Air Flow Volume
A measurement of the output of an air conditioner. It is computed by calculating the cubic feet per minute the air conditioner circulates.

Air Handler
A particular part of an air conditioner that is responsible for controlling and directing air throughout the ductwork. It distributes cooled or warmed air across the house.

Stands for Air Conditioning & Refrigeration Institute.

Stands for American Society of Heating, Refrigeration and Air Conditioning Engineer.


Stands for British thermal unit. It is a measurement standard used for assessing the amount of heat that is needed to increase 1 pound water temperature by 1 degree (Fahrenheit).

A cooling and heating measurement that is taken when evaluating an air conditioner or furnace’s power output. It is equal to around 1.06 kilojoules and can also be calculated by the hour which gives it the name BTUh.

A part of a furnace that is responsible generating heat from gas fuel or electric.

Burner (sealed combustion)
A part of a furnace that generates heat from the air outside the system.

Burner Orifice
A section of the burner that takes care of the gas input. After inputting, the gas is mixed with air and is used as fuel.


Refers to the ability of a cooling or heating equipment to fill a needed space.

Metric scale of measuring temperature. When used on water, the freezing point and boiling point is 0ヒsC and 100ヒsC respectively. Mentioned below is the process of converting temperature from Celsius to Fahrenheit: first multiplied by 9, then divided by 5 and then added 32.

CFM – (Cubic Feet per Minute)
Refers to the rate of air flow inside an air conditioner.

Refers to the process where refrigerant is added to an air conditioner. Stored inside a sealed system, the refrigerant is facilitates the cooling factor on the whole. The refrigerant passes from the evaporator indoor to the condenser outdoor and then again to the evaporator indoor.

An apparatus that pumps the refrigerant through a system that is sealed.

Refers to the process through which a chemical turns from vapor to liquid.

Condenser Coil/ Outdoor Coil
A section of an air conditioner that eliminates heat from the refrigerant in a vaporized form. After eliminating the heat, the refrigerant turns into liquid and goes back inside the appliance.

Condenser Fan
An apparatus that blows air on the condenser and thus keeps it cool.

An equipment that creates electrical current cycles. It turns on and off, joining and breaking the electrical current.

Crankcase Heater
An instrument that keeps the refrigerant in vapor form inside the system’s crankcase. The refrigerant maintains its vapor form by increasing the temperature of the oil of the crankcase, a temperature higher than the system’s coldest part.


Refers to a plate that opens and shuts to control the flow of air through the ductwork system.

DC – (Direct Current)
Electric current that uses a direct route to pass.

Refers to the process that removes the accumulation of ice off the outdoor coil. It generally occurs during cold weather when the air conditioning system is not used.

Refers to the measurement that is needed for a certain amount of space. It is equal to the temperature outside minus sixty five degrees Fahrenheit.

An instrument that draws humidity from air and cools down air to the level where water changes into liquid from vapor. Then, the humidifier takes out the liquid.

This equipment is placed over the ductwork and is used for separating air using a finned device that moves in different directions.

Stands for Department of Energy.

Downflow Furnace
A furnace that processes air from the top to the bottom.

Drain Pan
An instrument that catches any remaining condensate in the system, not all the systems require a drain pan.

Dry Bulb Temperature
A measurement of the intensity of heat exclusive of humidity. The measurement is calculated by dry bulb thermometer.

Dry Bulb Thermometer
An equipment that measures the temperature of air excluding the humidity.

An arrangement of pipes, used for transporting heat from the central heating or cooling system to an entire building.

The process of the refrigerant’s expansion. It controls heat.


Refers to the measurement of an air conditioner’s capacity of cooling. BTUh: electrical watt input.

A Federal Agency that promotes the use of environment-friendly, energy efficient and zero-pollution appliances in all industries, including air conditioning and heating.

Evaporator Coil/ Indoor Coil
An apparatus that eliminates heat and humidity from the air inside an entire building.

Expansion Valve
An equipment to measure the refrigerant’s temperature and pressure.


Scale of temperature. Mainly used in the United States. When used in water, the freezing and boiling point is 32ヒsF and 212ヒsF respectively. Mentioned below is the process to convert to the Celsius scale:
First subtract 32, then multiply the result by 5 and divide it by 9.

An appliance that creates air current by using motion.

Eliminates dust particles along with other debris from air. (Refer to MERV Rating).

Similar to a ventilator. Discharges exhaust gases.

Heating equipment. Produces heat for an entire building using fuel.

A part that acts as a protection against overcurrent. When there is a lot of running electricity, it melts and then breaks current.


Stands for Gas Appliance Manufacturers Association.

Gas Furnace Heat Exchanger
It transports heat from inside a furnace to the outside air. The duct system transports this air across an entire building.


Heat Exchanger
Lets heat be transported from the hot parts of the system to the cold parts.

Heat Gain
Refers to the total heat received by an area from all the heat conducting sources such as furnace, lighting, appliances, solar energy and respiration.

Heat Loss
Measurement of the rate at which heat emits from inside a building to outside.

Heat Pump
A compressor that maintains a cycle of cold or hot air inside a building.

Heat Transfer
The process through which heat is transported from one place to another.

Heating Coil
An equipment for conducting heat.

Per second measurement of electrical energy. Normal frequency: 6 Hertz.

Stands for Heating Seasonal Performance Factor. The measurement of the efficiency of heat over the course of a heating season.

A sensor for measuring and controlling humidity in the air.

A sensor for measuring and controlling humidity.

Measurement of the moisture level of air.

Humidity, Absolute
Humidity ratio between saturated air and non-saturated air. The grams of vaporized water in one cubic meter of air are measured to find it out.

Humidity, Relative
Ratio between the current humidity to the humidity of 100% saturated air.

Abbreviation for Heating, Ventilating and Air Conditioning.


Initialization of the combustion process. In order to turn into flame, it requires a gaseous mixture.


Kilowatt (kW)
Unit of measuring 1,000 watts of electricity.


Latent Heat
Type of heat that regulates the state of a substance.


The section of air cleaner that holds debris, dust particles and other air impurities. Could be made from polyester, charcoal, fiberglass or dog hair, among other things.

MERV Rating
Stands for Minimum Efficiency Reporting Value. The measurement provides an air cleaner’s efficiency value on a scale of 1 to 16.


Stands for National Energy Council / National Electric Code

Stands for National Electrical Manufacturing Association


Stands for Original Equipment manufacturer


Package Unit
A small unit used for heating and cooling homes. Generally kept on the roof or attic of a domestic establishment such as a house. This unit can be moved from one place to another without the need of disconnecting any lines of refrigerants.

Stands for Pounds per square inch

Stands for Pounds per square inch, absolute

Stands for Pounds per square inch gauge

Stands for Polyvinyl chloride. It is a plastic that is frequently used in buildings.


Reciprocating Compressor
An apparatus that works directly with crankshaft to deliver gases at high pressures.

Refers to the chemical that is used for cooling air. It expands and vaporizes, collects hot air and then contracts to turn into liquid to cool down the air.

Refrigerant Charge
The amount of refrigerant needed inside a system.


Seasonal Energy Efficiency Ratio. Measurement for determining the annual or seasonal cooling or heating efficiency of air conditioners and refrigeration appliances. Used countrywide and is a good means to find out the operating cost.

Self Contained System
(Refer to Package Unit)

Sensible Heat
Type of heat that has an impact on a substance’s temperature.

An instrument for measuring and regulating changes. Sensors in heating and air conditioning systems measure the temperature of air and humidity, along with some other things.


A part of thermostat that indicates the desired temperature for the indoors.

Spine Fin™ Coil

Outdoor coil that contains minuscular aluminum spines. Makes a larger surface area and betters the efficiency of the heat exchange process. It is a patented technology.

Split System

An appliance that combines both indoor and outdoor units. The commonest type of system.


An equipment that monitors and controls a cooling or heating system.

Unit of measuring the cooling or heating capacity of a cooling or heating appliance. 1 ton energy can melt 1 ton ice in a period of 24 hours.

Two-stage (cooling and heating)
An air conditioner that is engineered to run on both low as well as high settings during varied weather conditions. At the time of extreme weather, high setting is used whereas at the time of moderate weather, the low setting is used. This type of air conditioners can be used on long-term basis and create an optimum level of comfort in the temperature.

Thermostatic Expansion Valve. It measures liquid refrigerant’s flow into the evaporator at the same time calculating the vapor refrigerant that emits from the evaporator.


Heat flow’s resistance through building materials.

Refers to Underwriters Laboratories.

Upflow Furnace
Furnace that controls air from base to upwards.


A pressure that’s less than the pressure of the atmosphere. An example of perfect vacuum is 30 inches Mercury, symbolized as “Hg”.

Variable speed motor(s)
A fan that can be used for adjusting the speed as per the operation’s needs. This plays a part in the performance and efficiency of the system.

The unit of measuring the electrical force that is provided to the electrons in an electric circuit.

Force that presses electrical current through cables and wires.


An electrical power unit that is equal to one amp flow at one volt’s potential difference. It performs equal amount of work as one joule.

Wet Bulb Thermometer
Sensor for measuring gas and vapor in the air with the help of a bulb covered by a piece of soaked cloth.


Zoning System
A system that creates sections or zones into a building in order to control them individually.

Choose The Right Contractor

Finding the right contractor is very important when you are looking to replace your air conditioning system or room heating system. An expert professional is well-versed with the processes that will ensure not only a smooth installation but can also provide a long-term customer service. When you are looking for a contractor, keep the below mentioned factors in mind:

Find out if he/she has an updated license and whether he/she is a member of a domestic or national organization.

Better Business Bureau
You must find out whether they are registered members of the Better Business Bureau. On www.bbb.org, you will be able to explore the company background. This would give you a clear idea as to whether the company is of repute and whether it is reliable. It is not only essential to find out what kind of ratings they have got but to also know what kind of after-sales services they provide after some damage or problem occurs.

Request References
Ask for the references of the contractor’s previous and existing clients. People who have opted for their service before would definitely like to share their experience if they have been happy with it.

Warranties and Plans for Maintenance
Warranties, as well as guarantees, differ from one contractor to another. See to it that you thoroughly know the warranties and guarantees the company offers with your chosen equipment. Also, enquire about the maintenance plans they have.
Understand Everything and Obtain a Written Agreement

If your contractor refuses or seems unwilling to give you a written agreement of service where your warranties will be specified, do not do business with him. If you are having doubts or want to ask something, go ahead and ask.


Do you have a query regarding your recent HVAC events and/or your system? Are you looking for an answer? Derek Sawyers’ technicians and crew are trained with the right know-how to resolve any query. Feel free to send in your queries, it is our pleasure to assist you with answers.

In case of an emergency, get in touch with us at your local area:

Modesto 209-266-8682
Stockton (209) 623-1113
Fresno (559) 473-1222
Chico (209) 751-4035
Sacramento (916) 244-9600
(530) 230-0198

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Derek Sawyers has been providing you quality cooling and heating solutions for a long time. We will soon bring some more highly energy efficient products at amazing rates to keep you warm and cool as and when you need it.

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