Specifications
d. TWO OPENINGS OR VERTICAL DUCTS require 1
square inch (25.4 square mm)of free area per 4,000
Btuh (550 mm2/kW) for combined input of all gas
appliances in the space per Figure 6 and Table 3.
3. ONE OUTDOOR OPENING requires:
a. 1 sq. in. (25.4 square mm)of free area per 3,000 Btuh
(734 mm2/kW) for combined input of all gas
appliances in the space per Table 3 and
b. Not less than the sum of the areas of all vent
connectors in the space.
The opening shall commence within 12-in. (300 mm) of the
ceiling. Appliances in the space shall have clearances of at
least 1-in. (25 mm) from the sides and back and 6-in. (150 mm)
from the front. The opening shall directly communicate with the
outdoors or shall communicate through a vertical or horizontal
duct to the outdoors or spaces (crawl or attic) that freely
communicate with the outdoors.
Table 3 Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors
TWO HORIZONTAL DUCTS SINGLE DUCT OR OPENING TWO OPENINGS OR
VERTICAL DUCTS
(1 SQ. IN./2,000 BTUH) (1 SQ. IN./3,000 BTUH)
FURNACE (1,100 SQ. MM/KW) (734 SQ. MM/KW) (1 SQ. IN./4,000 BTUH)
INPUT (550 SQ. MM/KW)
Round Round
(BTUH) Free Area of Duct Free Area of Open- Duct Free Area of Open- Round Duct
Opening and Duct In. (mm) ing and Duct In. (mm) ing and Duct In. (mm)
Sq. In (Sq. mm) Dia Sq. In (Sq. mm) Dia Sq. In (mm) Dia.
40,000 * 20 (12904) 5 (127) 14 (8696) 5 (127) 10 (6452) 4 (102)
60,000 30 (19355) 6 (152) 20 (13043) 5 (127) 15 (9678) 5 (127)
80,000 40 (25807) 7 (178) 27 (17391) 6 (152) 20 (12904) 5 (127)
100,000 50 (32258) 8 (203) 34 (21739) 7 (178) 25 (16130) 6 (152)
120,000 60 (38709) 9 (229) 40 (26087) 7 (178) 30 (19355) 6 (152)
140,000" 70 (45161) 10 (254) 47 (30435) 8 (203) 35 (22581) 7 (178)
• Not all families have these models.
EXAMPLE: Determining Free Area
FURNACE WATER HEATER TOTAL INPUT
100,000 + 30,000 = (130,000 divided by 4,000)
60,000 + 40,000 = (100,000 divided by 3,000)
80,000 + 30,000 = (110,000 divided by 2,000)
= 32.5 Sq. In. for each two Vertical Ducts or Openings
= 33.3 Sq. In. for each Single Duct or Opening
= 55.0 Sq. In. for each two Horizontal Ducts
Table 4 Minimum Space Volumes for 100% Combustion, Ventilation and Dilution Air from Outdoors
OTHER THAN FAN-ASSISTEDTOTAL FAN-ASSISTEDTOTAL
(1,000'S BTUH GAS INPUT RATE) (1,000'S BTUH GAS INPUT RATE)
30 40 50 40 60 80 100 120 140
AOH Space Volume Ft3 (M3)
1,050 1,400 1,750 1,400 1,500 2,000 2,500 3,000 3,500
0.60 (29.7) (39.6) (49.5) (39.6) (42.5) (56.6) (70.8) (84.9) (99.1)
1,260 1,680 2,100 1,680 1,800 2,400 3,000 3,600 4,200
0.50 (35.6) (47.5) (59.4) (47.5) (51.0) (67.9) (84.9) (101.9) (118.9)
1,575 2,100 2,625 2,100 2,250 3,000 3,750 4,500 5,250
0.40 (44.5) (59.4) (74.3) (59.4) (63.7) (84.9) (106.1 ) (127.3) (148.6)
2,100 2,800 3,500 2,800 3,000 4,000 5,000 6,000 7,000
0.30 (59.4) (79.2) (99.1) (79.2) (84.9) (113.2) (141.5) (169.8) (198.1 )
3,150 4,200 5,250 4,200 4,500 6,000 7,500 9,000 10,500
0.20 (89.1) (118.9) (148.6) (118.9) (127.3) (169.8) (212.2) (254.6) (297.1)
6,300 8,400 10,500 8,400 9,000 12,000 15,000 18,000 21,000
0.10 (178.0) (237.8) (297.3) (237.8) (254.6) (339.5) (424.4) (509.2) (594.1)
0.00 NP NP NP NP NP NP NP NP NP
NP = Not Permitted
CONDENSATE TRAP
Condensate Trap-Upflow Orientation
When the furnace is installed in the upflow position, it is not
necessary to relocate the condensate trap or associated
tubing. Refer to Figure7 for upflow condensate trap
information. Refer to Condensate Drain section for information
how to install the condensate drain.
1. Loosen the clamp around the inlet of the vent elbow on
the inducer.
2. Rotate the vent elbow to the desired position and tighten
the clamp 15 in.-Ibs.
Condensate Trap-Downflow Orientation
When the furnace is installed in the downflow position, the
factory-installed trap will be located at the upper left corner of
the collector box. When the furnace is installed in the downflow
orientation, the factory-installed trap must be relocated for
proper condensate drainage.
10 Specificati ..... bject to change without notice. 440 01 4201 01