1 hvacr115 – mechanical for gas venting practices

1

HVACR115 – Mechanical for Gas

HVACR115 – Mechanical for Gas

Venting PracticesVenting Practices

2

04/19/23 2

Gas Vent Practices and Sizing

Natural-Draft Venting Practices

1) Must keep the flue gases at the correct temperature for venting.

A) These appliances are classified as Category I appliances.

Gas Vent Practices and Sizing

Natural-Draft Venting Practices

1) Must keep the flue gases at the correct temperature for venting.

A) These appliances are classified as Category I appliances.

3

04/19/23 3

2) Years ago wood and coal were used for heating a home.

a) When the heating system was change to gas the same chimney was used for venting gases.

b) The inside of these chimneys were coated with soot.

2) Years ago wood and coal were used for heating a home.

a) When the heating system was change to gas the same chimney was used for venting gases.

b) The inside of these chimneys were coated with soot.

4

04/19/23 4

c) It is very hard to heat these large chimneys with a gas appliance.

d) In many cases the chimneys were not cleaned before the appliance was installed and vented.

e) The temperature of chimney would allow the flue gases to condense.

c) It is very hard to heat these large chimneys with a gas appliance.

d) In many cases the chimneys were not cleaned before the appliance was installed and vented.

e) The temperature of chimney would allow the flue gases to condense.

5

04/19/23 5

f) The condensate would mix with the soot.

g) This would create an acid that would attack the chimney mortar joints.

f) The condensate would mix with the soot.

g) This would create an acid that would attack the chimney mortar joints.

6

04/19/23 6

3) Newer and safer methods for using chimneys are now used.

a) The modern chimney has a ceramic lining that heats faster than the chimney.

b) The lining is not in contact with the brick work.

3) Newer and safer methods for using chimneys are now used.

a) The modern chimney has a ceramic lining that heats faster than the chimney.

b) The lining is not in contact with the brick work.

7

04/19/23 7

c) There is an air space between the lining and the brick.

d) This air space acts as an insulator between the liner and the brick chimney.

e) When an old unlined chimney is encountered, a flexible liner can be used.

c) There is an air space between the lining and the brick.

d) This air space acts as an insulator between the liner and the brick chimney.

e) When an old unlined chimney is encountered, a flexible liner can be used.

8

04/19/23 8

5) Venting Material

a) Most common is the single-wall or double-wall metal vent pipe.

b) These pipes may also be called type B vent material.

5) Venting Material

a) Most common is the single-wall or double-wall metal vent pipe.

b) These pipes may also be called type B vent material.

9

04/19/23 9

c) Type B designates the temperature of the flue gases vented in the material.

d) Type B vent material is for low-temperature gas appliances.

e) With the flue gases below 550 degrees F.

c) Type B designates the temperature of the flue gases vented in the material.

d) Type B vent material is for low-temperature gas appliances.

e) With the flue gases below 550 degrees F.

10

04/19/23 10

6) Single wall vent pipe

a) Made out of metal

b) It is used when the flue pipe passes through a conditioned (heated) space.

6) Single wall vent pipe

a) Made out of metal

b) It is used when the flue pipe passes through a conditioned (heated) space.

11

04/19/23 11

c) The single-wall vent pipe cannot keep the flue gases up to temperature when a flue passes through a cool, unheated space.

d) Such as an attic in winter.

c) The single-wall vent pipe cannot keep the flue gases up to temperature when a flue passes through a cool, unheated space.

d) Such as an attic in winter.

12

04/19/23 12

7) Double-wall vent pipe

a) Used when the flue passes through a cool (unconditioned) space.

b) Used when a flue has to go through a wall, ceiling, or roof.

c) Used to prevent flue gases from cooling.

7) Double-wall vent pipe

a) Used when the flue passes through a cool (unconditioned) space.

b) Used when a flue has to go through a wall, ceiling, or roof.

c) Used to prevent flue gases from cooling.

13

04/19/23 13

8) Care should be used with double-wall pipe and fittings.

a) Screws must not be driven into the pipe.

b) It should be fitted together with twist-lock or snap lock fittings.

8) Care should be used with double-wall pipe and fittings.

a) Screws must not be driven into the pipe.

b) It should be fitted together with twist-lock or snap lock fittings.