Fireboxes and Dampers

Question 1

The function of a firebox is to:

Answer 1

The part of the fireplace that contains the fire.

Question 2

The side and back walls of a firebox slope to:

Answer 2

Connect the damper opening to the flue in a gentle slope so that the smoke is funneled up.

Question 3

A common minimum firebox depth requirement is ____________ inches.

Answer 3

20

Question 4

Metal fireboxes should be mortared tightly to the masonry of the fireplace.

Answer 4

False

Question 5

Clay tile flue liners should be supported on metal fireboxes.

Answer 5

False

Question 6

Lintels should be mortared tightly into place.

Answer 6

False

Question 7

Zero clearance fireplaces require footings and foundations.

Answer 7

False

Question 8

List eight common firebox problems.

Answer 8

1. Masonry or mortar loose, missing or deteriorated
2. Masonry or refractory cracked
3. Rust out, burnout, buckled or cracked metal fireboxes
4. Inappropriate materials
5. Designed for coal
6. Too shallow
7. Lintels rusted, sagging or loose
8. Draft suspect

Question 9

List two functions of a fireplace damper.

Answer 9

1. Allow exhaust products to leave the house during operation
2. Prevent cold air from entering the house when the fireplace is idle

Question 10

Can dampers ever be at the top of the chimney?

Answer 10

Yes

Question 11

Would you ever find a damper that was permanently open?

Answer 11

Yes, where gas logs have been inserted.

Question 12

List six common damper problems.

Answer 12

1. Missing
2. Inoperative or obstructed
3. Damper or frame rusted
4. Frame loose
5. Too low
6. Undersized (too small)

Question 13

Describe the location and shape of the throat, the smoke shelf and the smoke chamber.

Answer 13

1. Throat – top of firebox below and at the damper
2. Smoke shelf – area behind the damper that is nearly level
3. Chamber – sloping section of the fireplace above the damper and throat, but below the chimney flue

Question 14

Describe the characteristics of a well designed and well built smoke chamber.

Answer 14

The sides and front of the chamber should slope and the back should be vertical.

Question 15

List seven problems with throats, smoke shelves and smoke chambers.

Answer 15

1. Missing
2. Debris
3. Excess slope
4. Uneven slope
5. Wood forms not removed
6. Walls not smooth
7. Rust

Question 16

List six fireplace, face or breast problems.

Answer 16

1. Cracked
2. Settled (gap at wall)
3. Loose
4. Combustible clearances inadequate
5. Evidence of overheating
6. Too thick