Bock Water heaters OT300 Installation And Operation Instruction Manual page 10

SECTION III: PRE-INSTALLATION
Minimum clearance from combustible material is 0" for the sides, top, and back of this water
heater, as shown in Figure 3. This water heater is approved for installation in an alcove with
the clearances shown in Figure 3. For ease of access and proper maintenance, the clearances in
Figure 4 are required.
Minimum Clearance From Combustibles
Figure 3:
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. For natural gas models,
during operation at maximum input, the supply pressure at the gas control must be at least 6" W.C.
For LP gas models, during operation at maximum input, the supply pressure at the gas control
must be at least 8" 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
Table 3: Gas Supply Line Capacity
less and a pressure drop of 0.3" W.C.
Nominal
Internal
Iron Pipe
Diameter
Size
(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 OT300 and OT400.
For model OT500, 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.
Page 10
10 20 30 40
730 590 500
1,100 890 760
2,100 1,650 1,450
3,300 2,700 2,300
5,900 4,700 4,100
9,700 8,300
Figure 4:
Length of Pipe (feet)
50 60 70 80
440 400 370 350
670 610 560 530
1,270 1,150 1,050 990
2,000 1,850 1,700 1,600
3,600 3,250 3,000 2,800
7,400 6,800 6,200 5,800
Required Minimum Access Clearances
90 100 125 150
320 305 275 250
490 460 410 380
930 870 780 710
1,500 1,400 1,250 1,130
2,600 2,500 2,200 2,000
5,400 5,100 4,500 4,100
175 200
225 210
350 320
650 610
1,050 980
1,850 1,700
3,800 3,500