HVAC Fundamentals and Components: Indoor Air Quality, Heat Transfer, and System Design Save Groups

IAQ

Indoor Air Quality

Factors considered in IAQ

Humidity, ventilation, and occupant comfort

Primary purpose of HVAC in commercial buildings

Regulate indoor temperature, air quality, and humidity

ASHRAE acceptable comfort level for occupants

80%

Example of an internal heat gain

Lighting and equipment

Example of solar heat gain

Sunlight entering through windows and walls

Function of condenser coil in HVAC

Transfer heat from refrigerant to outdoor air

HVAC module that transfers heat outdoors

Condenser

Function of AHU (Air Handling Unit)

Distribute conditioned air, house filters, coils, and fans

Purpose of air distribution system

Distribute cooled/heated air

HVAC acronym meaning

Heating, Ventilation, and Air Conditioning

What is the building envelope?

Physical barrier separating interior from exterior (foundation, walls, roof, windows, doors)

How is ductwork measured?

Linear feet

CFM in duct design

Cubic feet per minute (airflow volume)

Cooling system with individual room control

Variable Refrigerant Flow (VRF)

Thermal imaging is used to identify

Insulation failures and air leaks

Cooler ductwork on thermal image indicates

Air leakage or missing insulation

Define thermal bridging

Heat flow through conductive materials bypassing insulation

Result of poor building pressurization control

Moisture infiltration, drafts, and door problems

IAPMO stands for

International Association of Plumbing and Mechanical Officials

Heat transfer by direct contact

Conduction

Rate of energy flow

Power

Component that releases absorbed indoor heat

Condenser

Component transporting air through building

Ductwork

Why is HVAC zoning important?

Allows independent temperature control in zones

Symbol for a supply diffuser in plans

Square with diagonal crosshairs

Thermal imaging primarily detects

Surface temperature variations

Factors in sensible heat load calculation

Occupants, lighting, and outside air temperature (all of the above)

Common unit for cooling capacity

BTU/hr

Purpose of bathroom exhausts

Remove odors, humidity, and gases

SEER stands for

Seasonal Energy Efficiency Ratio

Air returned back to the system

Return air

Main issue with clogged HVAC filters

Reduced airflow and efficiency

Purpose of a diffuser

To distribute air evenly in a space

Spread supply air

Spread supply air evenly into a room

Purpose of refrigerant line insulation

Prevent condensation and energy loss

Function of VAV box

Regulate airflow to zones

System that removes summer heat

Chiller

Component distributing warm/cool air

Air handler

Most critical factor in duct sizing

Airflow rate (CFM)

Typical component in RTU

Compressor

Function of return duct

Remove conditioned air back to unit

Which is NOT a major HVAC component

Water heater

Distribution system with precise zone control

VAV

Component that removes latent heat (moisture)

Cooling coil

Factor increasing cooling load

Higher internal lighting use

Where are boilers common

Large multi-story office buildings

Primary purpose of HVAC filters

Protect equipment & improve IAQ

Issue with filters with too high MERV rating

Restrict airflow, overwork blower motor

Thermal cameras detect what radiation

Infrared radiation

12,000 BTU/hr = how many tons

1 ton

One BTU

Heat to raise 1 lb of water by 1°F

Mechanical ventilation

Passive ventilation

Heat flows

From higher to lower temperature

Thermal imaging

Can detect insulation deficiencies & duct air leaks

An AHU

Moves & conditions air for delivery to spaces

Sealing air ducts

Can improve efficiency, reduce energy costs, and improve comfort

An insulating material with higher R-value

Provides greater resistance to heat transfer

Split HVAC system

Contains both an indoor and outdoor unit

In a ducted system

Supply air goes to spaces; return air goes back to equipment

Front

Back

A properly designed HVAC system considers occupancy, orientation, insulation. (True - False)

TRUE

Refrigerant has a low boiling point, making it ideal for HVAC systems. (True - False)

TRUE

R-value measures resistance to conductive heat flow. (True - False)

TRUE

Thermal bridging occurs when conductive materials bypass insulation. (True - False)

TRUE

One BTU = heat to raise 1 lb of water by 1°F. (True - False)

TRUE

Mechanical ventilation is passive ventilation. (True - False)

FALSE

Heat flows from higher to lower temperature. (True - False)

TRUE

Thermal imaging cannot detect heat loss/bridging. (True - False)

FALSE

“Air Conditioning” = comfort cooling with either chilled water or refrigerant. (True - False)

TRUE

ASHRAE thermal comfort = 90% of occupants comfortable. (True - False)

TRUE

VAVs allow independent temperature control in different zones. (True - False)

TRUE

Thermal imaging can detect insulation deficiencies & duct air leaks. (True - False)

TRUE

An AHU moves & conditions air for delivery to spaces. (True - False)

TRUE

Sealing air ducts can improve efficiency, reduce energy costs, and improve comfort. (True - False)

TRUE

An insulating material with higher R-value provides greater resistance to heat transfer. (True - False)

TRUE

Split HVAC system contains both an indoor and outdoor unit. (True - False)

TRUE

In a ducted system, supply air goes to spaces; return air goes back to equipment. (True - False)

TRUE

With positive air pressure, indoor pressure is lower than outside. (True - False)

FALSE

In HVAC design, mechanical ventilation does not use recirculated air—only fresh air. (True - False)

TRUE

Using a dirty or clogged air filter in a commercial HVAC system can reduce efficiency and increase energy costs. (True - False)

TRUE