3rd Year Gas Venting and Chimneys

what is the max negative building pressure when a category 1 appliances are installed?

.02" WC (5 Kpa )

What is the min clearance from combustibles for a type b vent?

1 inch of clearance.

What is the min size of a opening in a screen, louver or grille used for air supply?

1/4"

Using the rule of thumb, what is the formula to size a vent serving multiple appliances?

100% of the area of the largest appliance outlet, plus 50% of the sum of the additional outlet areas.

What is the minimum size area of a chimney?

12 inch squared .

What is the min height of an air supply inlet above grade level?

12"

What size of air supply duct is required for a draft hood equipped furnace of 125 Mbh and a draft hood equipped water heater of 60 Mbh?

125 mbh + 60 mbh = 185 mbh go to table 8.1 185 = 6" pipe

A fan assist furnace has 2 extra elbows installed in the vent connector, how much is the vent connector sizing table reduced?

15% each elbow = 30%.

What is the min termination height of a vent above a roof?

2 feet above a roof and 2 feet above obstructions within 10 feet.

What is the min dimension of a vent or chimney if it is not round?

2 inches .

If a combustible surface is protected with 28 ga . sheet metal spaced 1" from the surface, what is the min clearance from the surface for single wall vent connector?

2" of clearance.

How much reduction of the vent sizing table is required for a corrugated chimney liner?

20%.

What is the max developed length of an air supply duct allowed without increasing the size?

20'

What is the minimum gauge of aluminum vent connector?

22 b&SG

What is the min gauge of a vent connector for a gas fired appliance?

28 GSG

What is the minimum termination height of a chimney above a roof?

3 feet above a roof and 2 feet above obstructions within 10 feet.

what is the min size (diameter) of a type b vent?

3 inches.

What is the min size of a single wall vent connector?

3"

What is the smallest size a masonry chimney could be if it was round?

4 inches.

What size of ventilated metal thimble is required for a single wall vent connector less than 6 feet in length passing through a combustible wall?

4" larger than the diameter of the vent connector.

What is the min effective vent height of a vent or chimney?

5 feet.

A vent has the following attached to it. one 5" vent connector , one 4" vent connector and one 3" vent connector. what size would be needed for the vent?

5 x 5 = 25 4 x 4 = 16 divided by 2 = 8 3 x 3 = 9 divided by 2 = 4.5 25 + 8 + 4.5 = 37.5 SR = 7".

What is max temp rating for type L vent?

550 F

What is the max length of a single wall vent connector of four inch diameter?

6 ft ,18" per inch of diameter.

what is the min clearance between a non protected combustible surfaces and a single wall metal vent connector?

6 inches of clearance.

A single boiler with an 8" draft hood outlet is connected to a chimney. what size would be required for the chimney?

9" one size larger.

What is the min size (area) foe a square or rectangular used for air supply?

9" squared

a common type b vent has a furnace with a 5" flue collar and a domestic water heater with a 4" draft hoot outlet connected to it . what size is needed for the common vent?

A 6" vent is required . 5 x 5 = 25 4 x 4 = 16 divided by 2 = 8 25 + 8 = 33 square root = 6"

What type of appliance would be vented using type BW vent?

A recessed wall furnace.

A venting system has a common vent connector and a common vent offset. how much would the values in the vent sizing tables be reduced?

A total of 30%. 15% for every 90 elbow

A single appliance has a 5" diameter draft hood outlet. what size of venting system is required?

Rule of thumb same as 5".

A double wall vent pipe having an inner aluminum liner with a galvanized out wall separated by a dead air space having a maximum internal temp rating of 470 F?

Type B vent.

What type of damper is allowed for installation on an air supply duct in a dwelling?

a certified automatic damper.

A draft hood for hot water boilers is too tall to connect to the vent outlet opening and needs to be shortened. how mush are you permitted to cut off ?

a draft hood cannot be altered in any manner.

What is required when connecting a single wall vent connector in to a type b vent?

a draft hood connector.

What type of draft control device would be used for an incinerator?

a single acting barometric damper.

which method would be used to determine if there was draft in a venting system?

a smoke or match test.

The portion of the venting system that conducts the flue gases from the flue collar to the vent or chimney?

a vent.

What position should a draft hood be installed with respect to vertical and horizontal planes?

all draft hoods must be installed in the position they are approved for.

What is a direct vent appliance?

an appliance this is vented threw the wall rather than the roof.

what would be connected to a chimney rather than a vent?

an incinerator.

A common vent connector manifold has three 5" diameter vent connectors attached to it . what size would the common vent connector be?

common vent = 100 % of all 5 x 5 = 25 5 x 5 = 25 5 x 5 = 25 25 + 25 + 25 = 75 square root = 9" pipe

What principle causes vent draft?

convection.

What type of appliance would utilize a special venting system?

direct vent appliance.

What is the min size in diameter of a vent or vent connector?

equal to the area of a three inch pipe.

When using rule of thumb sizing, how is the size of the vent connector serving a single appliance determined ?

its always the same size of the draft hood outlet.

When using rule of thumb sizing , how is the size of a vent connector serving a single appliance with multiple draft hood outlets determined?

its is the combined area of all the outlets .

Where should an air supply duct terminate?

next to the burner of the largest input appliance.1 ft up 2 ft out.

What is the maximum size of a masonry chimney for a given installation?

not to exceed the appliances input by no MORE that 25%.

When using rule of thumb sizing, what is the minimum size of a chimney serving a single appliance?

one size larger that the vent connector.

What type of plastic pipe must be used to vent high efficient gas fired appliances?

system 636.

What makes an appliance a direct vent type?

the appliance will have a vent and air supply pipe connected directly to the appliance both terminating outdoors .

What is vent connector rise?

the distance from the appliance outlet to the center of the tee into the vent connection.

A vent has 2 appliances both with 5" diameter vent connector attached to it, which appliance should be connected to the bottom of the vent?

the one with the larger input.

A 5" and a 4" vent connector are connected to a common vent, how are the vent connectors arranged?

the smaller is connected highest.

What is the minimum dimensions of a vent if it is not round?

the vent can be any shape as long as the minimum dimension is not less than 2" and the area is equal to at least a 3" diameter pipe.

What type of vent damper may be added to an existing draft hood appliance?

thermal operated vent dampers only.

What is the purpose of the general venting requirements ?

to adjust the sizing tables to reflect variations in the installation.

What size of vent would be required for the installation of a common vent connector manifold that has three 5" vent connected to it?

vent = 100% of largest and 50 % of rest 5 x 5 = 25 5 x 5 = 25 divided by 2 = 12.5 5 x 5 = 25 divided by 2 = 12.5 25 + 12.5 x 2 = 50 square root = 8"

according to the code how should the slip joints in a single wall vent connector be fastened together?

with 3 sheet metal screws or other means of approval to prevent sagging.

How should a single wall vent connector be supported?

with non combustible hangers / supports.