Bosch 940 ES Installation And Operating Instructions Manual page 28

Installation instructions
If an external condensate drain (installer supplied) must be
installed (chapter 4.3.2), the following is recommended:
• 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
28
3" Venting Z-flex
90° 2SVEVWCF03 FST3 &
Condensate Drain
Tee
Horizontal 2SVEDWCF03 FSHDT3
Condensate Drain
Condensate Drain 2SVEDTK24
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.
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
940 ES – 6 720 644 930 (2019/09)
ProTech Heat Fab
93PPLSTEE
FSDF3
9321
N/A 7000TUBE
6720608542-07.1V