I(S)HRDV HORIZONTAL FLUE SIZING
Unit Type
Flue Pipe Diameter
Maximum Length of Flue Pipe
I(S)HRDV-100
4.0 IN
82.0 FT
I(S)HRDV-125
4.0 IN
82.0 FT
I(S)HRDV-160
4.0 IN
82.0 FT
I(S)HRDV-210
6.0 IN
72.0 FT
I(S)HRDV-250
6.0 IN
72.0 FT
I(S)HRDV-300
6.0 IN
72.0 FT
I(S)HRDV-400
6.0 IN
72.0 FT
Table II
Gas Supply Piping
Suggested pipe sizing for direct line from meter or propane tank is found in Table III. These sizes are based on 6” to
7” w.c. pressure at the meter for natural gas; 11” w.c. for propane gas, with .3” w.c. pressure drop schedule 40
pipe and fittings.
TABLE III
Input in 1000’s
BTU Hr.
Maximum Distance
from Meter
Natural*
Propane*
50 feet
¾”
½”
100 to125
100 feet
1”
¾”
60 feet
1”
¾”
150 to 175
100 feet
1 ¼”
1”
30 feet
1”
¾”
120 feet
1¼”
1”
200 to 250
250 feet
1½”
1¼”
75 feet
1¼”
1”
300
200 feet
1½”
1¼”
50 feet
1¼”
1”
400 to 420
100 feet
1½”
1¼”
35 feet
1 ¼”
1 ¼”
500
80 feet
1 ½”
1 ¼”
300 feet
2”
2”
50 feet
1½”
1¼”
600
200 feet
2”
2”
30 feet
1½”
1¼”
800
125 feet
2”
2”
80 feet
2 ”
2”
1000
200 feet
2½”
2”
50 feet
2 ”
2”
1200
150 feet
2½”
2¼”
30 feet
2 ”
2”
80 feet
2½”
2½”
1600
250 feet
3”
3”
The BTU input and output of these systems are listed in Table IV. See page 10.
*On units receiving inlet gas pressure in excess of 14” w.c., a high gas pressure regulator must be provided for
each heater section.
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