Unit 48 Principles of Combustion and Safety

The approximate heating value of methane is?

1000 BTUs per cubic foot.

Combustion air for gas appliances should be?

14 to 15 cubic feet of combustion air per 1000 BTU of firing rate.

The approximate heating value of propane is?

2500 BTUs per cubic foot.

The three things necessary for combustion are?

Fuel, oxygen, and heat.

What part does heat play in combustion?

Heat is the catalyst of combustion.

Propane is?

Heavier than air.

A combination of two elements makes up common fuel gases. Which of the following elements make up these fuel gases?

Hydrogen and carbon.

How does negative pressure affect the air supply of a furnace?

It increases the need for outside air.

LP gas is considered more hazardous than natural gas because?

LP tends to puddle in low areas but natural gas tends to dissipate.

Natural gas is?

Lighter than air.

What is the type of gas that is created as a byproduct of other manufacturing processes?

Manufactured gas.

Three broad categories of fuel gasses include?

Natural, manufactured, and liquefied petroleum.

What is the difference between primary air and secondary air?

Primary air is mixed with the gas before ignition and secondary air is drawn in after ignition.

Air that is mixed with the fuel before it is ignited is referred to as?

Primary air.

How is the Annual Fuel Utilization Efficiency (AFUE) efficiency rating determined?

Using the NIST equation for 100 percent efficiency minus losses.

The products of complete combustion of a hydrocarbon gas are?

Water and carbon dioxide.

Which of the following is a product of complete combustion?

Water vapor.

The products of incomplete combustion of a hydrocarbon gas are?

Water, carbon, carbon dioxide, and carbon monoxide.

Carbon monoxide is formed?

When the gas is not burning completely.

What type of flame is characteristic of incomplete combustion?

Yellow flames.

Flue gas condensation can be prevented by?

Using double wall vent.

Beginning in May 2013, the minimum AFUE rating for a new furnace in the southern part of the United States is.

80%.

How does certification affect heating equipment in the United States?

All heating equipment must be tested, certified, or listed by an accredited testing agency.

How do water and carbon dioxide relate to combustion?

Both are stable and safe products of combustion.

Compared to blue flames, yellow flames?

Burn at a lower temperature?

Agencies that set equipment standards and test equipment include?

CSA and AHRI.

Why is carbon monoxide production undesirable in furnace operation?

Carbon monoxide can cause illness.

Once a technician works on a system, what else should he or she do?

Check for gas leaks.

Which government agency is involved is setting gas fired equipment standards?

DOE.

How was natural gas created?

Decomposition of organisms converted into gas through pressure and heat.

What is the purpose of excess air in furnace combustion?

Excess air insures that all the gas is burned by making sure there is plenty of oxygen available.

Beginning in 2013, which region in the United States will have the highest minimum AFUE rating?

The North.

If carbon monoxide is a product of a reaction resulting in combustion, what can be said about the combustion?

The combustion was incomplete.

Annual Fuel Utilization Efficiency, AFUE, is?

The efficiency of the furnace for an entire heating season.

What does a certification done by the Canadian Standards Association (CSA) signify?

The equipment meets ANSI, UL, CSA America, or NSF standards.

What causes flue gas condensation?

The flue gas is cooled below the dewpoint of the combustion gas.

How do gas furnaces ensure the production of a blue flame?

The use of gas spuds and a manifold.

Soot forming in the heat exchanger can be caused by?

Too much gas in the gas air mixture.