Natural
If there are indications that incomplete combustion is occurring in a natural-draft furnace, the problem may be solved by _____.
increasing the amount of primary air
What is the temperature range of the flue gases produced by an induced-draft furnace?
275°F to 400°F (135°C to 204°C)
True or False: The vent pipe of a condensing furnace must be sloped downward in the direction of the furnace.
True
To what does the term temperature rise refer?
The temperature difference between the supply and return airstreams
In what location are Type B-W vent products used?
inside walls
Which condition can cause a backdraft in a natural-draft furnace?
A new wood-burning fireplace in a home
Regarding venting, induced-draft furnaces fall into which category?
Category I
When venting vertically through a roof, the combustion air intake should always be ________ than the ______ opening.
Lower than the vent opening
What is the term for the near-horizontal metal pipe that connects a furnace vent to a masonry chimney?
Vent connector
Under what circumstances can you vent a gas furnace through a lined masonry chimney serving a wood fireplace?
Under no circumstances should a furnace be vented with a fireplace through the same chimney.
They no longer manufacture Natural-draft furnaces
The vent connector for an induced-draft gas furnace _____.
can be single-wall metal pipe in some cases
Regarding venting, condensing furnaces fall into which category?
Category IV
What is the ACCA
Air Conditioning Contractors of America
How much clearance to combustibles is typically required for Type B vent pipe?
1"
What is the average heat-content value assigned to natural gas?
1,000 Btus per cubic foot
A low temperature rise in an induced-draft furnace __________
reduces the vent temperature
What type of material is used to vent a Condensing Furnace?
Schedule 40 PVC
A blue gas flame is typically produced when how much of the required combustion air is mixed with the gas before it is ignited?
50%
What will happen if a person is exposed to CO levels above 200 ppm for an extended period?
Loss of consciousness and eventual death
What does a Natural draft furnace lack, that an induced draft and condensing furnace have?
A blower
What type of pressure must be present for the primary air to be drawn in or induced into the gas stream as it enters the burner?
Negative Pressure
A direct-vented condensing furnace requires ________.
a combustion air intake routed outside of the space
What does AFUE stand for?
Annual Fuel Utilization Efficiency
What substance forms during incomplete combustion, has a sharp odor, and is hazardous?
Aldehydes