Bosch PROTANKLESS GWH 345/450 ESR - Manual (Page 19)

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Installation instructions
19
3.6.5 Vertical terminations
Horizontal runs
Any gas vent section that is greater than 45 degrees
from the vertical is considered horizontal. Horizontal
sections must slope upwards from heater at least ¼
inch for every foot of its horizontal length and be
properly supported. Under no circumstances should
the exhaust vent pipe pitch downward away from
heater. Pitch the termination to the outside 1/4" per foot
to prevent rain water from entering the pipe.
Vent terminations
The exhaust vent must terminate above the roof surface
with an approved vent cap not less than 2 feet (0.6 m)
above the highest point where it passes through the
roof and at least 2 feet (0.6 m) higher than any vertical
wall or similar obstruction within 10 feet (3.1m). See
Fig. 20 and Table 9.
Fig. 20 Vertical vent termination clearances
Interior masonry chimneys
The single wall stainless steel exhaust vent pipe must
be permanently mounted inside the masonry chimney.
The masonry chimney may have to be tile or metal lined
before the insertion of the gas vent pipe; check local
codes for clarification.
You may not vent any other fuel burning appliances into
any free space remaining in the chimney. The vent
terminator must extend at least 3 feet (0.9 m) above
where the chimney meets the roofline and at least 2 feet
(0.6 m) higher than any vertical wall or similar
obstruction within 10 feet (3.1 m). The top of the
chimney must be sealed to prevent rain water or other
elements from entering the chimney.
Exterior Masonry Chimney
Refer to the National Fuel Gas Code and consult a local
venting HVAC contractor. Not recommended in cold
climates.
3.6.6 Horizontal terminations
An approved vent terminator must be used. See Table 5
for known approved horizontal vent terminations.
Install a condensate drain if the total straight vent length
is greater than 5 feet or if the exhaust vent pipe passes
through an unconditioned space.
The exhaust termination tee must project out a minimum
of 10" and maximum of 16” on center from the wall
thimble.
Fig. 21 and table 10 show the required clearances for
the vent termination. Follow local codes if more
stringent.
Caution: Failure to install a
condensate drain may result in damage
not covered by the manufacturer's
warranty. See chapter 3.6.3. An
approved vent terminator must be used.
See Table 5 for known approved
vertical vent terminations.
GAS VENT TERMINATIONS FOR LISTED VENT
CAPS
Roof pitch H (min.)
feet
meters
Flat to 6/12 1.0 0.30
6/12 to 7/12 1.25 0.38
Over 7/12 to 8/12 1.5 0.46
Over 8/12 to 9/12 2.0 0.61
Over 9/12 to 10/12 2.5 0.76
Over 10/12 to 11/12 3.25 0.99
Over 11/12 to 12/12 4.0 1.22
Table 9 Termination heights at various roof pitches
Over 12/12 to 14/12 5.0 1.52
Over 14/12 to 16/12 6.0 1.83
Over 16/12 to 18/12 7.0 2.13
Over 18/12 to 20/12 7.5 2.27
Over 20/12 to 21/12 8.0 2.44
Warning: Pitch the last horizontal pipe
and the termination to the outside 1/4"
per foot to prevent rain water from
entering the pipe.
Table 9 Termination heights at various roof pitches