6 720 607 909
Installation instructions
15
Selecting combustion air inlet restrictor
Note: Before installing the combustion air inlet
accessory, the appropriate inlet air restrictor must
be determined using Tables
6
,
7
and
8
.
Refer to Fig.
16
for mounting sequence.
B
Determine the total length of the straight sections of
3" stainless steel exhaust and enter that length in line
1.
B
Do not count the first 90 elbow used in calculation.
Count the number of additional 90 elbows used and
enter that value in line 2. (Maximum of 4 90 elbows
allowed) and enter that value in line 2.
B
Count the number of 45° elbows used and enter that
value in line 3.
B
For model GWH 345 ESR, enter a 1 in line 4 for
model GWH 450 ESR enter a 1 in line 5.
B
Repeat steps 1 through 4 for the 3" intake pipe and
enter those values in the intake section.
B
Add the totals from the Exhaust table and the Intake
table to determine the equivalent vent length. Use
this value in Table 6 to determine which restrictor
size to use.
Note:
Do not count the first elbow used.
Example
Exhaust
• 10 - 3' straight sections
• 1 - 1' straight section
Total length 31'
• 2 - 90° elbow
• 1 - GWH 450 ESR termination.
Intake
• 5 - 4' straight sections
• 2 - 1' straight sections
Total length 22'
• 3 - 90° elbows
• 1 - GWH 450 ESR termination.
Example
Note:
Do not count the first elbow used.
Using table 8, the following restrictors would be
required:
• GWH 450 ESR NG - restrictor 55
• GWH 450 ESR LP - restrictor 55.
Exhaust
1
Straight section length
__ x 1 =
____
2
90° elbows (qty)
__ x 6 =
____
3
45° elbows (qty)
__ x 3 =
____
4
GWH 345 ESR termination
__ x 15 =
____
5
GWH 450 ESR termination
__ x 12 =
____
6
Total:
____
Combustion Air
1
Straight section length
__ x .5 =
____
2
90° elbows (qty)
__ x 3 =
____
3
45° elbows (qty)
__ x 1.5
____
4
GWH 345 ESR termination
__ x 6 =
____
5
GWH 450 ESR termination
__ x 3 =
____
6
Total:
____
7
Total equivalent vent length =
____
Table 6 Determining equivalent vent length (see
example in Table 7)
Exhaust
Straight section length
21 x 1 =
21
90° elbows (qty)
1 x 6 =
6
45° elbows (qty)
0 x 3 =
0
GWH 345 ESR termination
0 x 15 =
0
GWH 450 ESR termination
1 x 12 =
12
Total:
39
Combustion Air
Straight section length
22 x .5 =
11
90° elbows (qty)
2 x 3 =
6
45° elbows (qty)
0 x 1.5 =
0
GWH 345 ESR termination
0 x 6 =
0
GWH 450 ESR termination
1 x 3 =
3
Total:
20
Total equivalent vent length =
59
Table 7 Determining equivalent length example
