14
Gas Pressure Adjustment Locations
Gas Pressure Adjustment
Figure 14. Honeywell VR8340
Pipe Sizing for Gas Connection
The capacities shown below are based on using SCH
40 black iron pipe. For capacities using other materials,
consult local codes.
Maximum Equivalent Pipe Length (ft) (m)
Natural Gas 1000 BTU/FT
3
0.60 Specific Gravity @ 0.5 in.
WC Pressure Drop
Model
3/4"
1"
1-1/4"
1-1/2"
207A
25 (7.6) 90 (27.4) 360 (109.7)
n/a
266L/267A
15 (4.6) 50 (15.2) 210 (64.0) 445 (135.6)
337A
10 (3.0)
30 (9.1)
140 (42.7)
290 (88.4)
399L/407A
*
20 (6.1)
95 (29.0)
215 (65.5)
* 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 Rates
Model
Pipe Size
Min. GPM (lpm) Max. GPM (lpm)
207A
1-1/4"–1-1/2"–2"
20 (75)
100 (378)
266L/267A
1-1/4"–1-1/2"–2"
25 (95)
100 (378)
337A
1-1/4"–1-1/2"–2"
35 (132)
100 (378)
399L/407A
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
F10638-1
Figure 15. Polymer Headers Water Flow
F10637-1
Figure 16. Bronze Headers (ASME) Water Flow
Flow GPM
(lpm)
Pressure Drop
Ft. of Head (m of Head)
207A
266L/267A
337A
399L/407A
20 (75)
4.0 (1.2)
25 (95)
4.0 (1.2)
4.6 (1.4)
30 (113)
4.0 (1.2)
5.2 (1.6)
35(132)
4.0 (1.2)
5.8 (1.8)
5.2 (1.6)
40 (151)
4.6 (1.4)
5.8 (1.8)
5.2 (1.6)
5.2 (1.6)
50 (189)
4.6 (1.4)
6.3 (1.9)
6.9 (2.1)
6.9 (2.1)
60 (227)
4.6 (1.4)
6.9 (2.1)
6.9 (2.1)
6.9 (2.1)
70 (265)
4.6 (1.4)
8.1 (2.5)
9.2 (2.8)
9.2 (2.8)
80 (303)
4.6 (1.4)
9.2 (2.8)
9.8 (3.0)
9.8 (3.0)
90 (340)
6.9 (2.1) 10.4 (3.2) 10.4 (3.2) 10.4 (3.2)
100 (378)
8.1 (2.5)
11.0 (3.4) 12.1 (3.7) 12.1 (3.7)
Table K. Polymer Heat Exchanger Pressure Drop -
Residential Models (UG Fully Open)
