John Wood Power Vent 0.67 EF - Manual (Page 12)

Venting terminations and sizing
• Refer to Figure 8 and Table 2 for vent pipe materials
and sizing. Examples of the vent terminations are
shown in Figures 9 and 10. If the installation requires a
vent riser, suitable drainage must be provided to ensure
condensation does not accumulate. Termination
through a roof is shown Figure 11.
• G/JW 40, 50 and 60-gallon heaters are supplied with a
50mm (2 in.) termination elbow and (2) plastic "rodent
screens" (see Figure.7). The screen is required to keep
foreign objects, rodents and small birds from entering
the venting system and only one (1) screen is to be
installed in the termination elbow. These screens have
been sized to ensure maximum energy efficiency of the
venting system based on the "equivalent length" of the
vent piping. How to determine the equivalent length is
shown in Figure 8. The appropriate screen is to be
installed into the end of the termination elbow and
secured with a small amount of silicone sealant. This
will allow for easy removal for inspection and cleaning.
For installations using 76mm (3 in.) venting, use the
76mm (3 in.) termination elbow and screen (not sup-
plied).
• G/JW5065 high input models are supplied with a 76mm
(3 in.) termination elbow that includes a steel mesh
rodent screen.
– 12 –
Example for calculating equivalent feet.
Section “A” . . . . 0.15m . . (0.5 ft.)
90° elbow . . . . . 1.83m . . (6.0 ft.)
Section B . . . . . 0.31m . . (1.0 ft.)
45° elbow . . . . . 0.91m . . (3.0 ft.)
Section C . . . . . 0.46m . . (1.5 ft.)
45° elbow . . . . . 0.91m . . (3.0 ft.)
Section D . . . . . 4.57m . (15.0 ft.)
Total Equivalent 9.14m . (30.0 ft.)
Based on this example use the (fully open) rodent
screen for vent length greater than 6.1 equivalent
metres (20 equivalent ft.) (see Figure 7).
NOTE: VENT PIPE MUST BE SUPPORTED EVERY 1.2m (4 ft.). TO PREVENT VIBRATION, USE ISOLATION
PADS WHEN ATTACHING STRAPS TO FLOOR JOISTS, WALLS OR CEILINGS.
PVC ADAPTER
(SUPPLIED)
STRAP
150mm
(6 in.)
MIN.
45°
ELBOW
90°
ELBOW RODENT SCREEN
(INSTALL INTO
ELBOW)
Figure 8 General Venting Layout
TERMINATION
ELBOW
GROUND LEVEL OR
MAXIMUM SNOW
LINE*
WATER
HEATER
MODEL
SUFFIX
VENT PIPE
SIZE
* VENT
MATERIAL
(SCHEDULE 40)
MAXIMUM EQUIVALENT
VENT LENGTH
MINIMUM EQUIVALENT
VENT LENGTH
NVH,
PVH
50mm (2 in.) PVC**, CPVC 12.3m (40 ft.) + termination elbow
0.76m (2.5 ft.) + one 90° elbow +
termination elbow
NVH,
PVH
76mm (3 in.) PVC**, CPVC 24.4m (80 ft.) + termination elbow 12.3m (40 ft.) + termination elbow
G/JW5065
SNV,
SPV
76mm (3 in.) PVC, CPVC 12.3m (40 ft.) + termination elbow
0.91m (3 ft.) + one 90° elbow +
termination elbow
G/JW5065 LNV 76mm (3 in.) PVC, CPVC 19.8m (65 ft.) + termination elbow 6.9m (20 ft.) + termination elbow
G/JW40,
50, 60
Notes:
1. Use long radius elbows where possible. Minimum dis-
tance between 90º elbows should be 150mm (6 in.).
2. *Check local codes to determine which materials are
allowed in your area.
3. **Pipe assembly adapter must be used with PVC
venting material (see Figures 13, 14 & 15).
Table 2 Allowable Vent Lengths and Materials (Vert. and Horiz.).
Equivalent lengths of straight pipe for various elbows using
Schedule 40 PVC and CPVC.
Size Type
Short Sweep/
Short Radius
Long Sweep/
Long Radius
50mm (2 in.) 90° elbow 2.44m (8 ft.) 1.52m (5 ft.)
76mm (3 in.) 90° elbow 2.44m (8 ft.) 1.52m (5 ft.)
50mm (2 in.) 45° elbow 0.91m (3 ft.) 0.76m (2.5 ft.)
76mm (3 in.) 45° elbow 1.22m (4 ft.) 1.07m (3.5 ft.)