Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION AND VENTILATION OPENING…

(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

Section 1.11.0.

2019 CALIFORNIA MECHANICAL CODE 473

474 2019 CALIFORNIA MECHANICAL CODE

APPENDIX F SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION

AND VENTILATION OPENING DESIGN

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

(The content of this Appendix is based on Annex F and Annex I of NFPA 54)

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F 101.2 Examples Using Single Appliance Venting Tables. See Figure F 101.2(1) through Figure F 101.2(14).

Notes:

1. A is the equivalent cross-sectional area of the tile liner.
2. The appliance is permitted to be either Category I draft hood-equipped or fan-assisted type.

FIGURE F 101.2(3) VENT SYSTEM SERVING A SINGLE APPLIANCE

WITH A MASONRY CHIMNEY AND A TYPE B DOUBLE-WALL VENT CONNECTOR

to a tile-lined masonry chimney.

Notes:

1. A is the equivalent cross-sectional area of the tile liner.
2. The appliance is permitted to be either Category I draft hood-equipped or fan-assisted type.

FIGURE F 101.2(4) VENT SYSTEM SERVING A SINGLE APPLIANCE USING

A MASONRY CHIMNEY AND A SINGLE-WALL METAL

VENT CONNECTOR

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F 101.0 General.F 101.1 Applicability. This appendix provides general guidelines for sizing venting systems serving appliances equipped with draft hoods, Category I appliances, and appliances listed

Note: The appliance is permitted to be either Category I draft hood-equipped or fan-assisted type.

FIGURE F 101.2(1) TYPE B DOUBLE-WALL VENT SYSTEM SERVING A SINGLE APPLIANCE WITH A

TYPE B DOUBLE-WALL VENT

Note: The appliance is permitted to be either Category I draft hood-equipped or fan-assisted type.

FIGURE F 101.2(2) TYPE B DOUBLE-WALL VENT SYSTEM SERVING A SINGLE

APPLIANCE WITH A SINGLE-WALL

METAL VENT CONNECTOR

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APPENDIX F any other purpose or distributed to any other persons or parti es.

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FIGURE F 101.2(5) ASBESTOS CEMENT TYPE B OR SINGLE-WALL

METAL VENT SYSTEM SERVING A SINGLE

DRAFT HOOD-EQUIPPED APPLIANCE

a Type B double-wall common vent.

Note: Each appliance is permitted to be either Category I draft hoodequipped or fan-assisted type.

FIGURE F 101.2(7) VENT SYSTEM SERVING TWO OR MORE APPLIANCES WITH TYPE B DOUBLE-WALL VENT

AND SINGLE-WALL METAL VENT CONNECTORS

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attached to a Type B double-wall common vent.

Note: Each appliance is permitted to be either Category I draft hoodequipped or fan-assisted type.

attached to a tile-lined masonry chimney.

Notes:

1. A is the equivalent cross-sectional area of the tile liner.

2. The appliance is permitted to be either Category I draft hood-equipped or fan-assisted type.

3. A is the equivalent cross-sectional area of the tile liner.

Note: Each appliance is permitted to be either Category I draft hood- 2. The appliance is permitted to be either Category I draft hood-equipped or equipped or fan-assisted type. fan-assisted type.

FIGURE F 101.2(6) FIGURE F 101.2(8) VENT SYSTEM SERVING TWO OR MORE MASONRY CHIMNEY SERVING TWO OR MORE

» APPLIANCES WITH TYPE B DOUBLE-WALL VENT AND APPLIANCES WITH TYPE B DOUBLE-WALL «

FIGURE F 101.2(6) VENT SYSTEM SERVING TWO OR MORE APPLIANCES WITH TYPE B DOUBLE-WALL VENT AND

APPLIANCES WITH TYPE B DOUBLE-WALL

FIGURE F 101.2(8) MASONRY CHIMNEY SERVING TWO OR MORE

TYPE B DOUBLE-WALL VENT CONNECTORS

VENT CONNECTORS

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APPENDIX F

Notes:

1. A is the equivalent cross-sectional area of the tile liner.
2. Each appliance is permitted to be either Category I draft hood-equipped or fan-assisted type.

inch (102 mm) inside diameter common vent connector manifold shall not exceed 72 inches (1829 mm) in length. [See Section 803.2.3]

Note: This is an illustration of a typical manifolded vent connector. Different appliance, vent connector, or common vent types are possible. [See Section 803.2]

1. A is the equivalent cross-sectional area of the tile liner.
2. Each appliance is permitted to be either Category I draft hood-equipped or fan-assisted type. Note: This is an illustration of a typical manifolded vent connector. Differ ent appliance, vent connector, or common vent types are possible. [See Sec FIGURE F 101.2(9) tion 803.2] MASONRY CHIMNEY SERVING TWO OR

» MORE APPLIANCES WITH SINGLE-WALL FIGURE F 101.2(11)

METAL VENT CONNECTORS USE OF MANIFOLDED COMMON VENT CONNECTORS

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FIGURE F 101.2(9) MASONRY CHIMNEY SERVING TWO OR MORE APPLIANCES WITH SINGLE-WALL

FIGURE F 101.2(11) USE OF MANIFOLDED COMMON VENT CONNECTORS

METAL VENT CONNECTORS

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Note: This is an illustration of a typical offset vent. Different appliance, vent connector, or vent types are possible. [See Section 803.1 and Section 803.2]

FIGURE F 101.2(12) USE OF OFFSET COMMON VENT

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draft hood-equipped appliances. [See Table 803.2(5)]

FIGURE F 101.2(10) ASBESTOS CEMENT TYPE B OR SINGLE-WALL

METAL VENT SYSTEMS SERVING TWO OR MORE DRAFT HOOD-EQUIPPED APPLIANCES

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APPENDIX F any other purpose or distributed to any other persons or parti es.

the 5 inch (127 mm) diameter vent has an adjusted capacity of only 110 000 Btu/h (32 kW). In this case, the vent system shall be increased to 6 inches (152 mm) in diameter. See the following calculations:

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FIGURE F 101.2(13) MULTISTORY GAS VENT DESIGN PROCEDURE FOR EACH SEGMENT OF SYSTEM

F 101.3 Example 1: Single Draft Hood-EquippedAppliance. An installer has a 120 000 British thermal units per hour (Btu/h) (35 kW) input appliance with a 5 inch (127 mm) diameter draft hood outlet that needs to be vented into a 10 foot (3048 mm) high Type B vent system. What size vent should be used assuming: (1) a 5 foot (1524 mm) lateral single-wall metal vent connector is used with two 90 degree (1.57 rad) elbows or (2) a 5 foot (1524 mm) lateral singlewall metal vent connector is used with three 90 degree (1.57 rad) elbows in the vent system? (See Figure F 101.3)

Solution: Table 803.1.2(2) shall be used to solve this problem because single-wall metal vent connectors are being used with a Type B vent, as follows: (1) Read down the first column in Table 803.1.2(2) until the

row associated with a 10 foot (3048 mm) height and 5

(1) Read down the first column in Table 803.1.2(2) until the

row associated with a 10 foot (3048 mm) height and 5 foot (1524 mm) lateral is found. Read across this row until a vent capacity exceeding 120 000 Btu/h (35 kW) is located in the shaded columns labeled NAT Max for draft hood-equipped appliances. In this case, a 5 inch (127 mm) diameter vent has a capacity of 122 000 Btu/h (35.7 kW) and shall be permitted to be used for this application. (2) Where three 90 degree (1.57 rad) elbows are used in the

vent system, the maximum vent capacity listed in the

Where three 90 degree (1.57 rad) elbows are used in the

vent system, the maximum vent capacity listed in the tables shall be reduced by 10 percent. This implies that

122 000 Btu/h (35.7 kW) x 0.90 = 110 000 Btu/h (32 kW) for 5 inch (127 mm) vent From Table 803.1.2(2), select 6 inches (152 mm) vent. 186 000 Btu/h (54.5 kW) x 0.90 = 167 000 Btu/h (49 kW)

This figure is exceeding the required 120 000 Btu/h (35 kW). Therefore, use a 6 inch (152 mm) vent and connector where three elbows are used.

FIGURE F 101.2(14) PRINCIPLES OF DESIGN OF MULTISTORY

VENTS USING VENT CONNECTOR AND

COMMON VENT DESIGN TABLES

[See Section 803.2.12 through Section 803.2.15]

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APPENDIX F

FIGURE F 101.3 FIGURE F 101.4 SINGLE DRAFT HOOD-EQUIPPED APPLIANCE SINGLE FAN-ASSISTED APPLIANCE

FIGURE F 101.3 SINGLE DRAFT HOOD-EQUIPPED APPLIANCE

FIGURE F 101.4 SINGLE FAN-ASSISTED APPLIANCE

SINGLE DRAFT HOOD-EQUIPPED APPLIANCE SINGLE FAN-ASSISTED APPLIANCE

EXAMPLE 1 EXAMPLE 2

F 101.4 Example 2: Single Fan-Assisted Appliance.

material. In this case, Table 803.1.2(1) shows that, for a 30

» An installer has an 80 000 Btu/h (23.4 kW) input fan-assisted foot (9144 mm) high vent with 10 feet (3048 mm) of lateral,

EXAMPLE 1

F 101.4 Example 2: An installer has an 80 000 Btu/h (23.4 kW) input fan-assisted Single Fan-Assisted Appliance. appliance that shall be installed using 10 feet (3048 mm) of lateral connector attached to a 30 foot (9144 mm) high Type B vent. Two 90 degree (1.57 rad) elbows are needed for the installation. Is a single-wall metal vent connector permitted to be used for this application? (See Figure F 101.4)

Solution: Table 803.1.2(2) refers to the use of single-wall metal vent connectors with Type B vent. In the first column find the row associated with a 30 foot (9144 mm) height and a 10 foot (3048 mm) lateral. Read across this row, looking at the FAN Min and FAN Max columns, to find that a 3 inch (76 mm) diameter single-wall metal vent connector is not recommended. Moving to the next larger size single-wall connector

[4 inch (102 mm)] we find that a 4 inch (102 mm) diameter single-wall metal connector has a recommended maximum vent capacity of 144 000 Btu/h (42 kW). The 80 000 Btu/h (23.4 kW) fan-assisted appliance is outside this range, so the conclusion is that a single-wall metal connector shall not be used to vent the appliance using a 10 foot (3048 mm) of lateral for the connector. However, if the 80,000 Btu/hr (23.4 kW) input appliance is moved within 5 feet (1524 mm) of the vertical vent, a 4 inch (102 mm) single-wall metal connector shall be used to vent the appliance. Table 803.1.2(2) shows the acceptable range of vent capacities for a 4 inch (102 mm) vent with 5 feet (1524 mm) of lateral to be between 72 000 Btu/h (21.1 kW) and 157 000 Btu/h (46 kW).

Where the appliance cannot be moved closer to the vertical vent, then a Type B vent shall be used as the connector

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Solution: Table 803.1.2(2) refers to the use of single-wall metal vent connectors with Type B vent. In the first column find the row associated with a 30 foot (9144 mm) height and a 10 foot (3048 mm) lateral. Read across this row, looking at the FAN Min and FAN Max columns, to find that a 3 inch (76 mm) diameter single-wall metal vent connector is not recommended. Moving to the next larger size single-wall connector

.1.2(2) refers to the use of single-wall metal vent connectors with Type B vent. In the first column find the row associated with a 30 foot (9144 mm) height and a 10 foot (3048 mm) lateral. Read across this row, looking at the FAN Min and FAN Max columns, to find that a 3 inch (76 mm) diameter single-wall metal vent connector is not recommended. Moving to the next larger size single-wall connector

[4 inch (102 mm)] we find that a 4 inch (102 mm) diameter single-wall metal connector has a recommended maximum vent capacity of 144 000 Btu/h (42 kW). The 80 000 Btu/h (23.4 kW) fan-assisted appliance is outside this range, so the conclusion is that a single-wall metal connector shall not be used to vent the appliance using a 10 foot (3048 mm) of lateral for the connector. However, if the 80,000 Btu/hr (23.4 kW) input appliance is moved within 5 feet (1524 mm) of the vertical vent, a 4 inch (102 mm) single-wall metal connector shall be used to vent the appliance. Table 803.1.2(2) shows the acceptable range of vent capacities for a 4 inch (102 mm) vent with 5 feet (1524 mm) of lateral to be between 72 000 Btu/h (21.1 kW) and 157 000 Btu/h (46 kW).

material. In this case, Table 803.1.2(1) shows that, for a 30 foot (9144 mm) high vent with 10 feet (3048 mm) of lateral, the acceptable range of vent capacities for a 4 inch (102 mm) diameter vent attached to a fan-assisted appliance is between 37 000 Btu/h (10.8 kW) and 150 000 Btu/h (44 kW). ues.F 101.5 Example 3: Interpolating Between Table Val- An installer has an 80 000 Btu/h (23.4 kW) input appliance with a 4 inch (102 mm) diameter draft hood outlet that needs to be vented into a 12 foot (3658 mm) high Type B vent. The vent connector has a 5 foot (1524 mm) lateral length and is also Type B. Is this appliance permitted to be vented using a 4 inch (102 mm) diameter vent?

Solution: Table 803.1.2(1) is used in the case of an all Type B Vent system. However, since there is no entry in Table 803.1.2(1) for a height of 12 feet (3658 mm), interpolation shall be used. Read down the 4 inch (102 mm) diameter NAT Max column to the row associated with a 10 foot (3048 mm) height and 5 foot (1524 mm) lateral to find the capacity value of 77 000 Btu/h (22.6 kW). Read further down to the 15 foot (4572 mm) height, 5 foot (1524 mm) lateral row to find the capacity value of 87 000 Btu/h (25.5 kW). The difference between the 15 foot (4572 mm) height capacity value and the 10 foot (3048 mm) height capacity value is 10 000 Btu/h (3 kW). The capacity for a vent system with a 12 foot (3658 mm) height is equal to the capacity for a 10 foot (3048 mm) height plus two-fifths of the difference between the 10 foot (3048 mm) and 15 foot (4572 mm) height values, or 77 000 Btu/h (22.6 kW) + ² ⁄5 x 10 000 Btu/h (3 kW) = 81 000 Btu/h (23.7 kW). Therefore, a 4 inch (102 mm) diameter vent shall be used in the installation.

2019 CALIFORNIA MECHANICAL CODE 479

APPENDIX F any other purpose or distributed to any other persons or parti es.

F 102.0 Examples Using Common Venting Tables. F 102.1 Example 4: Common Venting Two DraftHood-Equipped Appliances. A 35 000 Btu/h (10.3 kW) water heater is to be common vented with a 150 000 Btu/h (44 kW) furnace, using a common vent with a total height of 30 feet (9144 mm). The connector rise is 2 feet (610 mm) for the water heater with a horizontal length of 4 feet (1219 mm). The connector rise for the furnace is 3 feet (914 mm) with a horizontal length of 8 feet (2438 mm). Assume single-wall metal connectors will be used with Type B vent. What size connectors and combined vent should be used in this installation? (See Figure F 102.1)

Solution:

Table 803.2(2) shall be used to size single-wall metal vent connectors attached to Type B vertical vents. In the vent connector capacity portion of Table 803.2(2), find the row associated with a 30 foot (9144 mm) vent height. For a 2 foot (610 mm) rise on the vent connector for the water heater, read the shaded columns for draft hood-equipped appliances to find that a 3 inch (76 mm) diameter vent connector has a capacity of 37 000 Btu/h (10.8 kW). Therefore, a 3 inch (76 mm) single-wall metal vent connector shall be used with the water heater. For a draft hood-equipped furnace with a 3 foot (914 mm) rise, read across the row to find that a 5 inch (127 mm) diameter vent connector has a maximum capacity of 120 000 Btu/h (35 kW) (which is too small for the furnace), and a 6 inch (152 mm) diameter vent connector has a maximum vent capacity of 172 000 Btu/h (50 kW). Therefore, a 6 inch (152 mm) diameter vent connector shall be used with the 150 000 Btu/h (44 kW) furnace. Since both vent connector horizontal lengths are less than the maximum lengths listed in Section 803.2.1, the table values shall be used without adjustments.

FIGURE F 102.1 COMMON VENTING TWO DRAFT

HOOD-EQUIPPED APPLIANCES

EXAMPLE 4

In the common vent capacity portion of Table 803.2(2), find the row associated with a 30 foot (9144 mm) vent height and read over to the NAT + NAT portion of the 6 inch (152 mm) diameter column to find a maximum combined capacity of 257 000 Btu/h (75 kW). Since the two appliances total 185 000 Btu/h (54 kW), a 6 inch (152 mm) common vent shall be used. F 102.2 Example 5(a): Common Venting a Draft Hood-Equipped Water Heater with a Fan-AssistedFurnace into a Type B Vent. In this case, a 35 000 Btu/h (10.3 kW) input draft hood-equipped water heater with a 4 inch (102 mm) diameter draft hood outlet, 2 feet (610 mm) of connector rise, and 4 feet (1219 mm) of horizontal length is to be common vented with a 100 000 Btu/h (29 kW) fanassisted furnace with a 4 inch (102 mm) diameter flue collar, 3 feet (914 mm) of connector rise, and 6 feet (1829 mm) of horizontal length. The common vent consists of a 30 foot (9144 mm) height of Type B vent. What are the recommended vent diameters for each connector and the common vent? The installer would like to use a single-wall metal vent connector. (See Figure F 102.2) Solution:

The 100 000 Btu/h (29 kW) furnace in this example falls within this range, so a 4 inch (102 mm) connector shall be permitted. Since the furnace vent connector horizontal length of 6 feet (1829 mm) is less than the maximum value listed in Section 803.2.1, the venting table values shall be used without adjustment. Where the furnace had an input rating of 80 000 Btu/h (23.4 kW), then a Type B vent connector shall be needed in order to meet the minimum capacity limit.

Water Heater Vent Connector Diameter. Since the water heater vent connector horizontal length of 4 feet (1219 mm) is less than the maximum value listed in Table 803.2(2), the venting table values shall be used without adjustment. Using the Vent Connector Capacity portion of Table 803.2(2), read down the Total Vent Height ( H ) column to 30 feet (9144 mm) and read across the 2 feet (610 mm) Connector Rise ( R ) row to the first Btu/h rating in the NAT Max column that is equal to or exceeding the water heater input rating. The table shows that a 3 inch (76 mm) vent connector has a maximum input rating of 37 000 Btu/h (10.8 kW). Although this rating is exceeding the water heater input rating, a 3 inch (76 mm) vent connector is prohibited by Section 803.2.18. A 4 inch (102 mm) vent connector has a maximum input rating of 67 000 Btu/h (19.6 kW) and is equal to the draft hood outlet diameter. A 4 inch (102 mm) vent connector is selected. Since the water heater is equipped with a draft hood, there are no minimum input rating restrictions.

Furnace Vent Connector Diameter. Using the Vent Connector Capacity portion of Table 803.2(2), read down the Total Vent Height ( H ) column to 30 feet (9144 mm) and across the 3 feet (914 mm) Connector Rise ( R ) row. Since the furnace has a fan-assisted combustion system, find the first FAN Max column with a Btu/h rating exceeding the furnace input rating. The 4 inch (102 mm) vent connector has a maximum input rating of 119 000 Btu/h (34.9 kW) and a minimum input rating of 85 000 Btu/h (24.9 kW).

he Total Vent Height ( H ) column to 30 feet (9144 mm) and across the 3 feet (914 mm) Connector Rise ( R ) row. Since the furnace has a fan-assisted combustion system, find the first FAN Max column with a Btu/h rating exceeding the furnace input rating. The 4 inch (102 mm) vent connector has a maximum input rating of 119 000 Btu/h (34.9 kW) and a minimum input rating of 85 000 Btu/h (24.9 kW).

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APPENDIX F

Common Vent Diameter. The total input to the common vent is 135 000 Btu/h (40 kW). Using the Common Vent Capacity portion of Table 803.2(2), read down the Vent Height ( H ) column to 30 feet (9144 mm) and across this row to find the smallest vent diameter in the FAN + NAT column that has a Btu/h rating equal to or exceeding 135 000 Btu/h (40 kW). The 4 inch (102 mm) common vent has a capacity of 132 000 Btu/h (39 kW) and the 5 inch (127 mm) common vent has a capacity of 202 000 Btu/h (59 kW). Therefore, the 5 inch (127 mm) common vent shall be used in this example. Summary: In this example, the installer shall use a 4 inch (102 mm) diameter, single-wall metal vent connector for the water heater and a 4 inch (102 mm) diameter, single-wall metal vent connector for the furnace. The common vent shall be a 5 inch (127 mm) diameter Type B vent.

FIGURE F 102.2 COMMON VENTING A DRAFT HOOD-EQUIPPED WATER HEATER WITH A FAN-ASSISTED FURNACE INTO A TYPE B

DOUBLE-WALL COMMON VENT

EXAMPLE 5(a)

F 102.3 Example 5(b): Common Venting into an InteriorMasonry Chimney. In this case, the water heater and fanassisted furnace of Example 5(a) are to be common-vented into a clay-tile-lined masonry chimney with a 30 foot (9144 mm) height. The chimney is not exposed to the outdoors below the roof line. The internal dimensions of the clay tile liner are nominally 8 inches (203 mm) by 12 inches (305 mm). Assuming the same vent connector heights, laterals, and materials found in Example 5(a), what are the recommended vent connector diameters, and is this an acceptable installation?

Solution: Table 803.2(4) is used to size common venting installations involving single-wall connectors into masonry chimneys.

Water Heater Vent Connector Diameter. Using Table 803.2(4), Vent Connector Capacity, read down the Vent Height (H) column to 30 feet (9144 mm), and read across the 2 feet (610

The local 99 percent winter design temperature needed to use Table 803.2(8) and Table 803.2(9) can be found in ASHRAE Handbook – Fundamentals. For Charlotte, North Carolina, this design temperature is 19°F (-7.2°C).

mm) Connector Rise (R) row to the first Btu/h rating in the NAT Max column that is equal to or exceeding the water heater input rating. The table shows that a 3 inch (76 mm) vent connector has a maximum input of 31 000 Btu/h (9 kW), while a 4 inch (102 mm) vent connector has a maximum input of 57 000 Btu/h (16.7 kW). A 4 inch (102 mm) vent connector shall be used.

Furnace Vent Connector Diameter. Using the Vent Connector Capacity portion of Table 803.2(4), read down the total Vent Height ( H ) column to 30 feet (9144 mm) and across the 3 feet (914 mm) Connector Rise ( R ) row. Because the furnace has a fan-assisted combustion system, find the first FAN Max column with a Btu/h rating exceeding the furnace input rating. The 4 inch (102 mm) vent connector has a maximum input rating of 127 000 Btu/h (37 kW) and an input rating of not less than 95 000 Btu/h (27.8 kW). The 100 000 Btu/h (29 kW) furnace in this example falls within this range, so a 4 inch (102 mm) connector shall be permitted.

Masonry Chimney. From Table F 102.3, the equivalent area for a nominal liner size of 8 inches (203 mm) by 12 inches (305 mm) is 63.6 of a square inches (0.041 m ² ). Using Table 803.2(4), Common Vent Capacity, read down the FAN + NAT column under the Minimum Internal Area of Chimney value of 63 to the row for 30 foot (9144 mm) height to find a capacity value of 739 000 Btu/h (217 kW). The combined input rating of the furnace and water heater, 135 000 Btu/h (40 kW), is less than the table value so this is an acceptable installation.

Section 803.2.17 requires the common vent area to not exceed seven times the smallest listed appliance categorized vent area, flue collar area, or draft hood outlet area. Both appliances in this installation have 4 inch (102 mm) diameter outlets. From Table F 102.3, the equivalent area for an inside diameter of 4 inches (102 mm) is 12.2 of a square inches (0.008 m ² ). Seven times 12.2 equals 85.4, which is exceeding 63.6, so this configuration is acceptable. Masonry Chimney.F 102.4 Example 5(c): Common Venting into an Exterior In this case, the water heater and fanassisted furnace of Examples 5(a) and 5(b) are to be commonvented into an exterior masonry chimney. The chimney height, clay-tile-liner dimensions, and vent connector heights and laterals are the same as in Example 5(b). This system is being installed in Charlotte, North Carolina. Does this exterior masonry chimney need to be relined? If so, what corrugated metallic liner size is recommended? What vent connector diameters are recommended? [see Table F 102.3 and Figure 803.1.2(6)]

Solution:

According to Section 803.2.20, Type B vent connectors are required to be used with exterior masonry chimneys. Use Table 803.2(8) and Table 803.2(9) to size FAN+NAT common venting installations involving Type-B double-wall connectors into exterior masonry chimneys.

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APPENDIX F any other purpose or distributed to any other persons or parti es.

Chimney Liner Requirement. As in Example 5(b), use the 63 square inch (0.04 m ² ) internal area columns for this size clay tile liner. Read down the 63 square inches (0.04 m ² ) column of Table 803.2(8) to the 30 foot (9144 mm) height row to find that the combined appliance maximum input is 747 000 Btu/h (218.9 kW). The combined input rating of the appliances in this installation, 135 000 Btu/h (40 kW), is less than the maximum value, so this criterion is satisfied. Table 803.2(9), at a 19°F (-7.2°C) design temperature, and at the same vent height and internal area used earlier, shows that the minimum allowable input rating of a space-heating appliance is 470 000 Btu/h (137.7 kW). The furnace input rating of 100 000 Btu/h (29 kW) is less than this minimum value. So this criterion is not satisfied, and an alternative venting design needs to be used, such as a Type B vent shown in Example 5(a) or a listed chimney liner system shown in the remainder of the example.

According to Section 803.2.19, Table 803.2(1) or Table 803.2(2) is used for sizing corrugated metallic liners in masonry chimneys, with the maximum common vent capacities reduced by 20 percent. This example will be continued assuming Type B vent connectors.

Water Heater Vent Connector Diameter. Using Table 803.2(1) Vent Connector Capacity, read down the total Vent Height (H) column to 30 feet (9144 mm), and read across the 2 feet (610 mm) Connector Rise (R) row to the first Btu/hour rating in the NAT Max column that is equal to or greater than the water heater input rating. The table shows that a 3 inch (76 mm) vent connector has a maximum capacity of 39 000 Btu/h (11.4 kW). Although this rating is greater than the water heater input rating, a 3 inch (76 mm) vent connector is prohibited by Section 803.2.20. A 4 inch (102 mm) vent connector has a maximum input rating of 70 000 Btu/h (20.5 kW)

TABLE F 102.3 MASONRY CHIMNEY LINER DIMENSIONS WITH CIRCULAR EQUIVALENTS*

• Where liner sizes differ dimensionally from those shown in this table, equivalent diameters shall be permitted to be determined from published tables for square and rectangular ducts of equivalent carrying capacity or by other engineering methods.

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APPENDIX F

and is equal to the draft hood outlet diameter. A 4 inch (102 mm) vent connector is selected.

Furnace Vent Connector Diameter. Using Table 803.2(1), Vent Connector Capacity, read down the total Vent Height (H) column to 30 feet (9144 mm), and read across the 3 feet (914 mm) Connector Rise (R) row to the first Btu/h rating in the FAN MAX column that is equal to or greater than the furnace input rating. The 100 000 Btu/h (29 kW) furnace in this example falls within this range, so a 4 inch (102 mm) connector is adequate.

Using Table 803.2(1), Vent Connector Capacity, read down the total Vent Height (H) column to 30 feet (9144 mm), and read across the 3 feet (914 mm) Connector Rise (R) row to the first Btu/h rating in the FAN MAX column that is equal to or greater than the furnace input rating. The 100 000 Btu/h (29 kW) furnace in this example falls within this range, so a 4 inch (102 mm) connector is adequate.

Chimney Liner Diameter. The total input to the common vent is 135 000 Btu/h (40 kW). Using the Common Vent Capacity portion of Table 803.2(1), read down the total Vent Height (H) column to 30 feet (9144 mm) and across this row to find the smallest vent diameter in the FAN + NAT column that has a Btu/h rating greater than 135 000 Btu/h (40 kW). The 4 inch (102 mm) common vent has a capacity of 138 000 Btu/h (40.4 kW). Reducing the maximum capacity by 20 percent results in a maximum capacity for a 4 inch (102 mm) corrugated liner of 110 000 Btu/h (32 kW), less than the total input of 135 000 Btu/h (40 kW). So a larger liner is needed. The 5 inch (127 mm) common vent capacity listed in Table 803.2(1) is 210 000 Btu/h (62 kW), and after reducing by 20 percent is 168 000 Btu/h (49.2 kW). Therefore, a 5 inch (127 mm) corrugated metal liner should be used in this example. Single Wall Connectors. Once it has been established that relining the chimney is necessary, Type B double-wall vent connectors are not specifically required. This example could be redone using Table 803.2(2) for single-wall vent connectors. For this case, the vent connector and liner diameters would be the same as found for Type B double-wall connectors.

(2) Determine the total required volume.

The standard method to determine combustion air shall be used to calculate the required volume. The combined input for the appliances located in the basement is calculated as follows: 100 000 Btu/h (29 kW) + 40 000 Btu/h (11.7 kW) = 140 000 Btu/h (41 kW) The standard method requires that the required volume be determined based on 50 cubic feet per 1000 Btu/h (4.83 m ³ /kW). Using Table F 103.0 the required volume for a 140 000 Btu/h (41 kW) water heater is 7000 cubic feet (198.22 m ³ ).

Conclusion: Indoor volume is insufficient to supply combustion air since the total of 3600 cubic feet (101.94 m ³ ) does not meet the required volume of 7000 cubic feet (198.22 m ³ ). Therefore, additional combustion air shall be provided from the outdoors.

(3) Determine ratio of the available volume to the required

volume.

volume.

3600 cubic feet = 0.51 7000 cubic feet

(4) Determi ne the reduction f actor to be used to reduce the

full outdoor air opening size to the minimum required

Determi ne the reduction f actor to be used to reduce the

full outdoor air opening size to the minimum required based on ratio of indoor spaces.

F 103.0 Example of Combination Indoor and Out-door Combustion Air Opening Design. Determine the required combination of indoor and outdoor combustion air opening sizes for the following appliance installation example.

Example Installation: A fan-assisted furnace and a draft hoodequipped water heater with the following inputs are located in a 15 foot by 30 foot (4572 mm by 9144 mm) basement with an 8 foot (2438 mm) ceiling. No additional indoor spaces shall be used to help meet the appliance combustion air needs. Fan-Assisted Furnace Input: 100 000 Btu/h (29 kW) Draft Hood-Equipped Water Heater Input: 40 000 Btu/h (11.7 kW)

Solution: (1) Determine the total available room volume.

Appliance room volume. 15 feet by 30 feet (4572 mm by 9144 mm) with an 8 foot (2438 mm) ceiling = 3600 cubic feet (101.94 m ³ )

1.00 – 0.51 (from Step 3) = 0.49

(5) Determine the single outdoor combustion air opening

size as if combustion air is to come from outdoors. In this example, the combustion air opening directly communicates with the outdoors.

140 000 Btu/h = 47 square inches (0.03 m ² ) 3000 British thermal units per square inch (Btu/in ² )

(6) Determine the minimum outdoor combustion air open ing area.

Outdoor opening area = 0.49 (from Step 4) x 47 square

inches (0.03 m ² ) = 23 square inches (0.01 m ² ) Section 701.7.3(3) requires the minimum dimension of the air opening shall be not less than 3 inches (76 mm).

2019 CALIFORNIA MECHANICAL CODE 483

APPENDIX F any other purpose or distributed to any other persons or parti es.

TABLE F 103.0 STANDARD METHOD: REQUIRED VOLUME, ALL APPLIANCES

[NFPA 54: TABLE A.9.3.2.1]

0.0283 m ³

484 2019 CALIFORNIA MECHANICAL CODE

CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE