Bosch 830 ES Manual page 19

• 1. Install condensate drain on a horizontal section of the exhaust pipe
as close to the heater as possible.
• 2. The condensate must be disposed of according to local codes.
• 3. To install condensate drain in vent system, use PVC 3" X 3" X 1.5"
tee (part# 196278) and reduce for drain connection.
Fig. 22 External condensate drain installation (combustion air piping
not shown)
[1] Appliance
[2] Condensate drain trap
[3] Elbow
[4] Firestop support
[5] Rain cap
[6] Storm collar
[7] Flashing
[8] 4" minimum air space
[9] Condensate drain Tee
3" Venting Z-flex
90° 2SVEVWCF03
Condensate
Drain Tee
Horizontal 2SVEDWCF03
Condensate
Drain
Condensate 2SVEDTK24
Drain Tube
Table 21 Approved Condensate Drain Part Numbers
4.3.6 Freeze prevention
In cold climates, components of a tankless water heater can freeze and
burst from negative draft. A leading cause of negative draft is
combustion appliances in the building not being supplied with sufficient
combustion air. A wood stove or furnace can pull its combustion air from
the water heater's vent pipe, allowing the cold incoming air to freeze the
cold water in the heat exchanger. Supplying more combustion air for all
combustion appliances is the solution. A HVAC specialist should be
consulted to design solutions for providing more combustion air.
830 ES
ProTech Heat Fab
FST3 & FSDF3 93PPLSTEE
FSHDT3 9321
N/A 7000TUBE
Listed below is an additional measure designed to further limit backdraft
in extreme conditions assuming all other possible causes have been
addressed.
Solution One
The Z-flex vent termination hood is the preferred option for limiting
backdraft under the following conditions (see fig. 23):
• The vent hood is only to be used in the exhaust vent piping.
• The vent hood can only be used for horizontal terminations.
• The vent hood is able to meet the required clearances outlined in the
venting section of the water heater's installation manual.
Fig. 23 Part nr. 2SVSHTD03 for 3" venting
Part nr. 2SVSHTD04 for 4" venting
Solution Two
If the required clearances of the Zflex termination hood cannot be met,
the Zflex damper is the preferred alternative (see fig. 24).
Fig. 24 Part nr. 2ZVBP03 for 3" venting
Part nr. 2ZVBP04 for 4" venting
Installation
For this solution to be effective, the internal flapper must be 100%
closed when the water heater is not running. Refer to Figures 25 and 26
for preferred installation positions in the vent system.
If using the Zflex damper:
• Ensure directional arrow on damper label faces in the same direction
as exhaust flow.
• If installed horizontally, the axis must be horizontal or slightly pitched
up towards termination to ensure damper closes 100% when heater
is not running.
• To allow accessibility, damper must not be installed in an enclosed
section of vent pipe.
• Do not install damper in unconditioned spaces (e.g. attics)
Condensation can build up while the heater is running which can later
freeze and potentially block the flapper
Installation instructions | 19
6720608542-07.1V
6720608542-08.1V
6 720 644 936 (2013/01)