Bock Water heaters OT300-A Installation And Operation Instruction Manual page 9

SECTION III: PRE-INSTALLATION (cont.)
LOCATION (cont.)
For ease of access and proper maintenance, the clearances in Figure 3 are strongly recommended.
GAS SUPPLY LINE
Prior to installation, contact your local gas utility to confirm that sufficient gas service is available
for the water heater. The gas meter must have adequate capacity to supply the rated maximum gas
input of the water heater in addition to other gas fired equipment connected to the meter.
Minimum Gas Supply Pressure
The gas supply must be capable of maintaining a minimum pressure at the inlet of the gas control
during water heater operation at maximum input. The pressure will be lowest at the gas control
during water heater operation (i.e. gas is flowing) at maximum input. At minimum, during
operation at maximum input, the supply pressure at the gas control must be at least 6" W.C.
Refer to Table 3 for gas supply line sizing. The table shows maximum input in thousands of BTU's
per hour for various pipe sizes and lengths. The table assumes gas supply pressures of 14" W.C. or
less and a pressure drop of 0.3" W.C.
Table 3: Gas Supply Line Capacity
Nominal
Internal
Iron Pipe
Diameter
Size
10
(inches)
(inches)
1 1/4 1.380 1,050
1 1/2 1.610 1,600
2 2.067 3,050
2 1/2 2.469 4,800
3 3.068 8,500
4 4.026 17,500 12,000
At minimum, use 1-1/4" gas supply pipe for models OT300N(-A) and OT400N(-A).
For model OT500N(-A), use a minimum of 1-1/2" pipe.
Maximum Gas Supply Pressure
The gas supply pressure shall never be greater than 14" W.C. Pressures greater than 14" W.C. may
damage the gas control which could cause a fire or explosion.
Refer to Section IV: Installation / Gas Connections for further installation instructions.
Figure 3: Recommended Minimum Access Clearances
20 30 40 50
730 590 500 440
1,100 890 760 670
2,100 1,650 1,450 1,270
3,300 2,700 2,300 2,000
5,900 4,700 4,100 3,600
9,700 8,300 7,400
Length of Pipe (feet)
60 70 80 90
400 370 350 320
610 560 530 490
1,150 1,050 990 930
1,850 1,700 1,600 1,500
3,250 3,000 2,800 2,600
6,800 6,200 5,800 5,400
100 125 150 175
305 275 250 225
460 410 380 350
870 780 710 650
1,400 1,250 1,130 1,050
2,500 2,200 2,000 1,850
5,100 4,500 4,100 3,800
200
210
320
610
980
1,700
3,500
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