Carrier bryant 915SB Installation, Start-Up, Operating And Service And Maintenance Instructions Download

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915SB: Installation, Start-up, Operating and Service and Maintenance Instructions

Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.

Table 13 – Deductions from Maximum Equivalent Vent Length - Ft. (M)

NOTES

1. Use only the smallest diameter pipe possible for venting. Over-sizing may cause flame disturbance or excessive vent terminal icing or freeze-up.

2. NA - Not allowed. Pressure switch will not close, or flame disturbance may result.
3. Vent sizing for Canadian installations over 4500 ft. (1370 M) above sea level are subject to acceptance by the local authorities having jurisdiction.
4. Size both the combustion air and vent pipe independently, then use the larger size for both pipes.
5. Assume the two 45

elbows equal one 90

elbow. Wide radius elbows are desirable and may be required in some cases.

6. Elbow and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
7. The minimum pipe length is 5 ft. (2 M) linear feet (meters) for all applications.
8. Use 3-in. (76 mm) diameter vent termination kit for installations requiring 4-in. (102 mm) diameter pipe.
9. A running Tee in the Combustion Air Pipe adds 0 ft. to the TEVL of the vent length.

The measured length of pipe used in a single or 2-pipe termination is

included in the total vent length. Include deductions from the Maximum

Equivalent Vent Length (MEVL) contained in the Venting Tables for

elbows and flexible vent pipe. Factory accessory concentric vent

terminations or pipe lengths and elbows used for “standard” vent

terminations do not require a deduction from the Maximum Equivalent

Vent Length. See vent termination figures associated with

Table 12

Include a deduction for a Tee when used for Alberta and Saskatchewan

terminations.

NOTE:

Polypropylene venting systems MAY require additional

deductions from the MEVL, or additions to the TEVL, for vent

terminations and flexible pipe sections. See the polypropylene venting

system manufacturer’s instructions for details on equivalent lengths of

vent terminations and flexible vent pipes, and for calculating total vent

lengths.
To calculate the Total Equivalent Vent Length (TEVL) of the venting

system:

1. Measure the individual distance from the furnace to the termination

for each pipe.

2. Count the number of elbows for each pipe.
3. For each pipe, multiply the number of elbows by the equivalent

length for the type of elbow used. Record the equivalent length of

all the elbows for each pipe.

4. If a Tee is used on the termination (Alberta and Saskatchewan,

when required) record the equivalent length of the Tee used.

5. Calculate Total Equivalent Vent Length by adding the equivalent

lengths of the fittings to the lengths of the individual vent and

combustion air pipes.

6. When using polypropylene venting systems with flexible vent

pipes, perform adjustments for the equivalent length of the flexible

vent pipe to the calculated total equivalent venting system length.

See the polypropylene vent system manufacturer’s instructions for

details.

7. Select a diameter of vent pipe from

Table 12

and note the

Maximum Equivalent Vent Length (MEVL) shown for that

application for that specific furnace input size. Compare the Total

Equivalent Vent Length (TEVL) to the MEVL:

8. If the Total Equivalent Vent Length is

shorter

than the Maximum

Equivalent Vent Length for the diameter of pipe chosen, then that

diameter of pipe selected may be used.

9. If the Total Vent Length is

longer

than the Maximum Equivalent

Vent Length for the diameter of pipe chosen, that diameter pipe

MAY NOT be used for venting the furnace. Try the next larger

diameter pipe

NOTE:

If the calculated Total Equivalent Vent Lengths results in

different diameter pipes for the vent and combustion air, select the larger

diameter for both pipes.

NOTE:

If the Maximum Vent Length for diameter of the pipe selected

is longer than the measured length and the equivalent length of all the

fittings and terminations (TEVL), recalculate Total Equivalent Vent

Length using the next smaller diameter. If the Maximum Equivalent

Vent Length is still longer than the longer TEVL of the vent pipe or

combustion air pipe, then that diameter of pipe selected may be used.
When installing vent systems pipe lengths of 10 ft. (3 M) or less, use the

smallest allowable pipe diameter. Using a pipe size greater than required

for short venting systems may result in loss of efficiency, incomplete

combustion, flame disturbance, or flame sense lockout.
For vent systems longer than 10 ft. (3 M), any larger diameter vent pipe

shown in

Table 12

FOR THAT SIZE FURNACE

may be used.

Combustion Air and Vent Piping Insulation

Guidelines

NOTE:

Use closed cell, neoprene insulation or equivalent.

The vent pipe may pass through unconditioned areas. The amount of

exposed pipe allowed is shown in

Table 14

1. Using winter design temperature (used in load calculations), find

appropriate temperature for your application and furnace model.

2. Determine the amount of total and exposed vent pipe.
3. Determine required insulation thickness for exposed pipe length(s).
4. When combustion air inlet piping is installed above a suspended

ceiling, the pipe

MUST

be insulated with moisture resistant

insulation such as Armaflex or other equivalent type of insulation.

5. Insulate combustion air inlet piping when run in warm, humid

spaces.

6. Install the insulation per the insulation manufacturer’s installation

instructions.

NOTE:

Pipe length (ft. / M) specified for maximum pipe lengths

located in unconditioned spaces cannot exceed total allowable pipe

length as calculated from