15
Gas Pressure Adjustment Locations
GAS PRESSURE ADJUSTMENT
Honeywell VR8340 (Heater Models 268A and 408A)
GAS PRESSURE ADJUSTMENT
Robertshaw 7000 BDER (Heater Model 268A)
GAS
PRESSURE
ADJUSTMENT
Figure 14. Robertshaw 7000 DERHC (Heater Model 408A)
Electronic Ignition Gas Valves
Pipe Sizing for Gas Connection
These capacities shown below based on using SCH
40 black iron pipe. For capacities using other materials,
consult local code.
Maximum Equivalent Pipe Length (ft) (m)
Natural Gas 1000 BTU/FT
3
0.60
Specific Gravity @ 0.5 in WC Pressure Drop
Propane Gas 2500 BTU/FT
3
1.53
Specific Gravity @ 0.5 in WC Pressure Drop
Model
3/4"
1"
1-1/4"
1-1/2"
N
P
N
P
N
P
N
P
268A
15
(4.6)
35
(10.7)
50
(15.2)
125
(38.1)
210
(64.0)
480
(146.3)
445
(135.6)
408A
*
15
(4.6)
20
(6.1)
55
(16.8)
95
(29.0)
225
(68.6)
215
(65.5)
480
(146.3)
* A 3/4" gas line can be used for up to 5' (1.5 m) maximum length from the gas valve
in addition to the sediment trap.
Table I. Gas Pipe Sizing
Flow Rate
Model
Pipe Size
Min. GPM (lpm)
Max. GPM
(lpm)
268A
1-1/4"–1-1/2"–2"
25 (95)
100 (378)
408A
1-1/4"–1-1/2"–2"
40 (151)
100 (378)
* When flow rates exceed maximum GPM an external auxiliary bypass valve is
required. See external bypass valve section for details.
Table J. Min/Max Flow Rates
F10637-2
Figure 15. Bronze Header Water Flow
RELEASED
For Reference Only
