Appliances and Flue Systems

Question 1

What are B vent appliances?

Answer 1

Category 1 gas appliances that rely on natural draft for proper venting. Must terminate vertically above the roof.
NOT appliances that require BW, incinerators, appliances easily converted to other fuels, or Category 2, 3, or 4.

Question 2

What is a wythe?

Answer 2

The masonry divider separating two flues of terra cotta tile within the same chimney

Question 3

What factors influence the need for a reline?

Answer 3

Defective or cracked flue
Misalignment of tile
Spalling
Defective joints
Improper joint material
oversized flue
When the appliance requires it

Question 4

What is a catalytic combuster?

Answer 4

It is designed to increase combustion efficiency of wood heating system by lowering ignition temperature of flue gases passing through it from 100 degrees F to 500 degrees F, decreasing smoke.

Question 5

What are the different types of dampers?

Answer 5

throat dampers
top mounted dampers
factory built fireplace
connector pipe damper
barometric damper- not good for wood

Question 6

What is a hearth stove?

Answer 6

A free-standing stove designed with a rear flue collar exit that is low enough to fit under the fireplace lintel and use the fireplace chimney.

Question 7

What are the different material types of woodstoves?

Answer 7

Steel, cast iron, and soapstone.

Question 8

What are modular precast chimneys?

Answer 8

Factory made, pre-assembled chimneys that go together like legos on the job site. Require heavy equipment to install.

Question 9

What is a thimble?

Answer 9

a fixed or removable ring, tube, or lining located in the hole where the connector pipe passes through the wall.

Question 10

What is a wall pass-through?

Answer 10

A type of thimble for combustible walls that provide added protection.

Question 11

What are heat reclaimers?

Answer 11

aka heat extractor, fits in connector directly behind or above the woodstove. Increases creosote buildup.

Question 12

What is a throat damper?

Answer 12

located in fireplace throat.
Has a valve plate/damper blade and either a rotary, lever, or poker control.

Most common-
vestal damper- fishbone handle
allied/donely damper- smaller, fishbone or rotary
majestic damper- large round hole in center of handle

Question 13

What are factory built chimneys?

Answer 13

Two types:
Factory built fireplace chimneys- follow UL127, appliance and venting system tested as a single unit.
Woodstove chimneys- UL1482, UL103HT. often use black connector pipes from appliance to chimney. ULC5641.
Single wall- 18” clearance
Double wall- 6” clearance

Question 14

What are the different types of gas venting systems?

Answer 14

B-vent - double walled
Direct vent - 80 percent or new gas appliances. Draw outside air for combustion. Types of direct vent- co-axial and co-linear.
Gas relining systems- can be rigid or flexible
Specialty gas vents- can be plastic, PVC, or metal, includes power vent (fans)

Question 15

What are the different stainless steel alloys?

Answer 15

304/304L- wood and pellet
316/316L/316Ti- wood, pellet, coal, oil, category 1 gas.
321- wood, pellet. Not commonly used anymore.
AL29-4C - gas and biofuel

Question 16

Why do we insulate liners?

Answer 16

Reduces heat transfer
Lowers chance of pyrolysis
Maintains good draft

Question 17

What are the different ways to insulate a liner?

Answer 17

blanket wrap
pre-insulated
filling void with vermiculite/thermix loose insulation

Question 18

What is the proper masonry construction of a terra cotta flue?

Answer 18

Tiles are stacked one on top of the other and secured with non-water-soluble refractory cement designed to hold strength at 1000+ degrees F. Common mortar deteriorates.

Question 19

What are “slammers?”

Answer 19

Unlined wood stove insert simply slid into a fireplace opening. Prohibited by NFPA 211 in 1984.

Must be rectified either by:
A direct connect liner extending to first flue tile to bypass the smoke chamber
A positive connect liner extending to the top of the chimney.