interNACHI How to Inspect HVAC Systems

A(n) _____ draft is when the furnace has a fan that sucks air into the combustion chamber, through the heat exchanger, and blows out through the venting system.

induced

An induced-draft furnace uses a fan to pull air _____ the burner.

into

A common gas piping material is black _____.

iron

Natural gas has no color or odor, and ______ toxic.

is not

According to the InterNACHI® Home Inspection Standards of Practice, the inspector ___________ to determine the BTU, size and capacity of the furnace.

is not required

According to the InterNACHI® Home Inspection Standards of Practice, the inspector ______________ to inspect window and through-wall air conditioning units.

is not required

A mid-efficiency gas furnace's pilot light ____________.

is shut off when the furnace is not in operation

Condensate lines or sweating suction lines can ______ onto building materials.

leak

Natural gas is _________ air.

lighter than

High-efficiency furnaces use the principle that as hot gases cool, they release a lot of heat energy as they change their state from a gas to a(n) ______.

liquid

According to plumbing standards, there should be a __________ located at the gas meter.

lockable valve

There are basically two types of steam heating systems: _________________.

low-pressure and high-pressure

A(n) ____________ can be used to tell the difference between aluminum pipes and steel pipes.

magnet

A home inspector is required to describe the heating ____________.

method

According to the InterNACHI® Home Inspection Standards of Practice, a home inspector is required to describe the heating __________.

method

The intermittent pilot is the main distinguishing characteristic for a _____-efficiency furnace.

mid

A home inspector will typically find the ______-port burners installed in a furnace with a forced-draft, as they are common with high-efficiency furnaces.

mono

The color of an oil flame of a oil-fired heating system should appear _________.

orange and yellow

R-410A is replacing older refrigerants because it does not deplete _____.

ozone

If you are inspecting a _______ duct system, you should find a large rectangular duct that comes directly out of the heating system and runs in a straight line down the center of the basement, attic or ceiling.

plenum

If you are inspecting a(n) _______ duct system, you should see a large rectangular duct that comes directly out of the heating system and runs in a straight line down the center of the basement, attic or ceiling.

plenum

In a conventional gas furnace with a natural draft, _____ air is that which mixes initially with the gas before going to the burners.

primary

In a gravity hot-water heating system, the specific gravity of water at different temperatures makes the water circulate throughout the system without the use of a _____.

pump

Every hot-water heating system circulates water either by a ______________.

pump or by gravity

When a high-efficiency condensing furnace is operating, a _____________ of condensate water may drain out every 30 minutes.

quart

Heat can move from one body to another by _________.

radiation

Heat transferred through electromagnetic waves happens via __________.

radiation

Heat-emitting units are the ________, baseboard convectors, or other heat-emitting components from which the heat is transferred into the room or space of the building.

radiators

Gas compression cooling involves the compression and expansion of __________ and the transfer of heat.

refrigerant gas

A steam heating system should have a Hartford return connection, which prevents total loss of water from the boiler if there is a water leak in the _____ line.

return

The efficiency of the air circulation in a house with a gravity warm-air heating system depends on the temperature difference between the warm air ________ and the cool air ________.

rising... falling

Round or square supply ducts that are connected to and branch off the extended duct are called _____.

side takeoffs

According to modern standards, air-conditioning condensing units and heat pump units should have a readily accessible electrical disconnect within _____ of the unit.

sight

In a one-pipe hydronic system, a _____ pipe carries the hot water to the radiators or baseboard convectors, and it also carries the cool water back to the boiler or water heating unit.

single

Modern blower fans of forced-air HVAC systems on furnaces have multiple ________.

speeds

The warm air in a gravity warm-air heating system rises up through warm-air ducts or pipes that are also known as __________.

stacks

The older gas furnaces have a(n) ______ pilot light that is always burning.

standing

The appropriate BTU for a furnace is determined by _____________________.

the amount of heat the unit needs to produce in order to replace heat loss

Electricity may be considered a fuel, but it can also be _____________.

the heat-conveying medium

The higher the AFUE rating, ____________.

the more efficient the furnace

Flue pipes from two fuel-burning appliances should NOT enter a chimney from opposite sides at __________.

the same height

The first step in the heating cycle for a conventional oil furnace is ____________.

the thermostat calls for heat

An inspector should describe the energy source or ___________ in the inspection report.

the type of heating fuel

The heat from a warm-air heating system is distributed throughout the home either by gravity or ____________.

the use of a circulating/blower fan

A __________is used in standing-pilot light gas furnaces to determine whether the pilot flame is lit before the main gas valve is opened to supply gas to the burners.

thermocouple

A steam _____ is a device installed on a steam line to control the flow of steam, air and condensate.

trap

T/F: A moisture meter comes in both invasive and non-invasive models.

true

There may be at least ________ heat exchangers inside a high-efficiency furnace.

two

A(n) _____ forced-air furnace could be designed for low clearances, and both the warm-air outlet and return-air inlet are located at the top of the furnace.

upflow

A home that has a fuel-fired heating system requires _________________.

venting of its combustion gases and byproducts to the outside

A home inspection is a non-invasive, _____________ examination of a residential property.

visual

Heat moves from the ________ body, and the ________ body absorbs it.

warmer, colder

Burning natural gas creates ____________________.

water (vapor) and carbon dioxide

The flue pipe of a fuel-burning heating system should be ___________ diameter size as the outlet of the furnace, and it should never be reduced.

at least the same

A(n) _______ burner uses an electrical pump and a nozzle that turns the oil from a liquid to a spray of fine droplets.

atomizing

The lack of dilution air may cause a condition of ___________ at the furnace.

backdraft

The ___________ provides a proper draft in the oil furnace by automatically reducing (or diluting) the chimney draft to the optimal amount.

barametric damper

Radiation is the transfer of heat energy _________________.

by electromagnetic waves

On a conventional oil furnace, there is a safety device in operation when the burner is shooting flames called a ___________.

cadmium sulfide photo-cell, or cad cell

Solid-fuel, forced warm-air furnaces can burn _____________.

coal or wood

The three types of ignition systems do not include ____________.

cold-spark

The ____________ is what "carries" the heat from the source to the enclosure being heated.

heat-conveying medium

You may be able to describe a heating system by its _____________.

heat-conveying medium

A stack relay senses _______ instead of _______.

heat... light

Central air-conditioning units can be integrated with central ____________.

heating systems

The gas piping installed after the meter is usually the responsibility of the ____________.

homeowner

A warm-air supply duct that runs _____ from the furnace plenum to a riser is called a leader.

horizontally

A hydronic heating system is a forced ______ heating system.

hot-water

A hydronic heating system is a forced ____________ heating system.

hot-water

In relation to building science, heat moves from the ________ body, and the _________ body absorbs it.

hotter... colder

Heat is transferred _____________.

in direct rays

"________" describes a type of heating system.

Hydronic

________ only smells because a scent has been added to it in order to help us identify leaks.

Natural gas

________ air is air that mixes with the gas before going to the burners.

Primary

____________ and baseboard convectors are considered heat-emitting components.

Radiators

The efficiency of a cooling system in a residential installation is expressed in terms of its ______.

SEER

The efficiency of cooling systems in a residential installation is expressed in terms of its Seasonal Energy Efficiency Ratio (______).

SEER

_____________ is what carries the heat from the source to the enclosure being heated.

The heat-conveying medium

_______________ is an effective means of inspecting for water leaks and moisture problems.

Thermography

T/F: In a forced warm-air heating system, the cool air returns through the ducts and back to the furnace, where it is re-heated.

True

T/F: Steam is considered a heat-conveying medium.

True

_________ is the heat-conveying medium for hydronic heating systems.

Water

____________ is one of the main concerns when inspecting the HVAC system.

Water (or moisture)

As hot gases cool, they release a lot of heat energy as they change their state from ____________.

a gas to a liquid

If the heating system is a high-efficiency, gas-fired furnace, then the heat-conveying medium is _____.

air

Propane gas has a specific gravity of 1.5 and is heavier than __________.

air

To ignite natural gas, you need a mixture of gas and ______.

air

You may find a gravity hot-water heating system installed in __________.

an older home.

Changes in the direction of ducts are made by _____________.

angle ducts

The components and accessories for coal furnaces and wood furnaces __________.

are almost identical

Air filters should be installed in the return plenum or duct ___________.

in the path of the air that enters the HVAC system

The air movement from a warm-air heating system may cause __________.

indoor air-quality issues caused by agitated dust and other particles

Air has a specific gravity of ______.

1

The PVC venting pipe should be sloped down and toward the high-efficiency furnace or up and away from the furnace at ______ per linear foot.

1/4-inch

When an air conditioner is running, the house air might have a temperature drop of around ________ degrees as the air moves across the evaporator coil.

14 to 22°F (-10 a -5.5°C)

On low-pressure boilers, the pressure-relief valve is set to open at a pressure of ____ psi in the boiler.

15

A hot-water system that supplies hot water at temperatures higher than _________ is referred to as a high-temperature system.

250° F

A conventional low-efficiency, natural-draft, gas-fired furnace requires about ____ cubic feet of air for every cubic foot of gas burned.

30

A conventional oil furnace with a cast-iron burner likely has an AFUE rating of ______________.

60%, which is categorized as low-efficiency

One cubic foot of water at 68° F weighs about ____ pounds.

62

The U.S. government has established a minimum rating for furnaces of _________.

78%

The minimum efficiency rating for furnaces is ___________.

78%

The energy efficiency of a natural gas furnace is measured by its ________ rating.

AFUE (annual fuel utilization efficiency)

_____ is used as the medium to convey the heat in a forced-air furnace.

Air

___________ can be used to check for wood rot and damage caused by a leak from a condensing unit.

An awl or probe

A ______ is approximately the amount of energy needed to heat 1 pound of water by 1 degree Fahrenheit.

BTU

_____ is the transfer of heat from one molecule to another, or through one substance to another.

Conduction

_____ are typically formed in concentric cones or pyramids.

Diffusers

__________ refers to the flow of gases through the heat generating equipment.

Draft

The following are types of fuel used in residential heating: ______________.

Electricity, wood, gas

T/F: A natural-draft HVAC system has a forced-draft fan.

False

Cold air is never created in a gas-compression air-conditioning system, but instead, _____ is transferred from one place to another.

Heat

_____ is transferred from the metal of the heat exchanger to the house air that passes through the exchanger.

Heat

The __________ is located inside the outdoor condenser unit and receives the low-pressure refrigerant vapor through the suction line, and compresses or squeezes it into a smaller volume at a higher pressure.

compressor

High-efficiency condensing HVAC systems produce excessive _______________.

condensate

Forced-air furnaces function primarily by ________.

convection

Heat transferred within a gas or liquid happens via __________.

convection

Steady-state efficiency measures how efficiently a furnace ___________.

converts fuel to heat

The first step in the operation of a warm-air heating system is ______________.

cool air enters the furnace

The simultaneous ignition of all the burners of a gas-fired heating furnace can be provided by a gas burner component called a __________.

crossover igniter

When in regular operation, ash and other debris should be removed _______ from the combustion chamber of a wood-burning heater.

daily

A home inspector is required to ______________ the energy source.

describe

The ______ is the temperature of saturation at a certain atmospheric pressure. For a given atmospheric pressure, it is the temperature at which moisture condenses into water droplets (or dew).

dew point

The _______________ is the temperature below which the water vapor contained in the flue gas will turn into condensation.

dew point temperature

A(n) _______ furnace is also referred to as a counter-flow furnace or a down-draft furnace.

downflow

The energy _______ of a natural-gas furnace can be measured by its Annual Fuel Utilization Efficiency (AFUE).

efficiency

The ___________ of the heating system can be cited to distinguish one heating system from another.

efficiency and capacity

In a typical residential air-conditioning system, the _________ absorbs the heat energy from the air passing through it and transfers the heat energy from the passing air to the refrigerant moving inside it.

evaporator

In a typical residential air-conditioning system, the __________ absorbs the heat energy from the air passing through it, and transfers the heat energy from the passing air to the refrigerant moving inside it.

evaporator

Expansion tanks are necessary on hot-water heating systems because hot water _______.

expands

Expansion tanks are necessary on hot-water heating systems because hot water ____________.

expands

Gas-compression cooling involves the compression and __________ of refrigerant gas and the transfer of heat.

expansion

If you are inspecting a perimeter duct system, you should see supply registers located around the __________ of the room at the floor area.

exterior walls

The _____________ is installed inside the furnace plenum where it senses the air temperature that passes through that area. It controls the operation of the furnace within a temperature range.

fan and limit switch

A heat shield prevents ___________.

flame rollout

There are two broad categories to describe furnace heating systems: gravity warm-air furnaces and ______ warm-air furnaces.

forced

If a fan is used to distribute the air from a warm-air heating system, it's more properly known as a _____________.

forced warm-air heating system

Most heating systems can be categorized in _____ ways.

four

There are ___________ types of heat-conveying mediums.

four

At the burner nozzle of the gun assembly for an oil furnace, ____________.

fuel is combined with air.

The __________ is a device that measures the volume of gas entering a building.

gas meter

A ____________ is needed in order to safely perform maintenance and servicing of the heating system.

gas shut-off valve

A draft hood is installed on standing-pilot __________ furnaces.

gas-fired

Hot-water heating systems circulate water by either a pump (forced hot-water heating system) or by _______ (gravity hot-water heating system).

gravity

The primary way the air of a ______ warm-air furnace moved through the house relied on how ________ affected the different weights of warm and cool air.

gravity, gravity

The distinguishing characteristic of a gravity steam-heating system is that the condensate returns to the boiler from the heat-emitting units by ___________.

gravity, rather than by some mechanical means

In relation to furnace ductwork, a supply register is similar to a _______, but a register has a damper to control the air flow.

grille

Water _____ is a problem with a steam heating system when condensed water is trapped in a section of a horizontal steam pipe.

hammer

Burning natural gas (CH4) with oxygen yields carbon dioxide (CO2), water vapor (2H20), and ________.

heat

Burning natural gas with oxygen yields carbon dioxide, water vapor, and ________.

heat

A(n) ________ transfers heat from one place to another; it can take heat from the outdoor air and bring it to the inside of a building and release it.

heat pump

A home inspection report may likely describe a heating system by its ______________.

heat-conveying medium