Bosch 940 ES Installation Manual page 17

Fig. 20
B Attach the combustion air inlet accessory (8 705
504 154) to the top of the unit (position 3) using the
3 screws and gasket provided, and install air intake
pipe over the accessory. NOTE: The appliance has
the option to mount the combustion air inlet acces-
sory on the top right or on the top left side of the
heater. The combustion air inlet that is not used must
be kept sealed.
Fig. 21
B Ensure that exhaust vent pipe is fully inserted in collar
to enable proper connection.
Exhaust venting must be 3" or 4" sealed
i
single wall stainless steel (AL29-4C) vent
pipe.
3.3.5 Condensate drain installation
Note: Do not install condensate drain in areas where it
may freeze.
1. Install condensate drain as close to heater as possi-
ble.
2. Use 3/8" ID high temperature silicone tube to con-
nect to condensate drain port. Do not use copper pip-
ing for any portion of the condensate drain.
3. Form a condensate trap by means of a 3" loop par-
tially filled with water.
4. To increase the tube length, connect to end of the
high temperature silicone tubing with vinyl tubing, PVC
or CPVC pipe. Do not reduce the internal diameter at
6 720 644 930
any point.
5. Dispose of condensate according to local codes.
10' MIN.
2' MIN.
3' MIN.
FIRESTOP SUPPORT
ELBOW
DRAIN TRAP
TO DRAIN - DISPOSE
OF CONDENSATE
ACCORDING TO
LOCAL CODES
APPLIANCE
Fig. 22 Condensate drain installation (combustion air
piping not shown)
3" Venting Z-flex
90° 2SVEVWCF03
Condensate
Drain Tee
Horizontal 2SVEDWCF03
Condensate
Drain
Condensate 2SVEDTK24
Drain Tube
Table 18 Approved Condensate Drain Part Numbers
3.3.6 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 com-
bustion appliances is the solution. A HVAC specialist
should be consulted to design solutions for providing
more combustion air.
Listed below are additional measures designed to fur-
ther limit backdraft in extreme conditions assuming all
other possible causes have been addressed.
Installation instructions
RAIN CAP
STORM COLLAR
FLASHING
4" MIN.
AIR SPACE
CONDENSATE
DRAIN TEE
6720608782-04.2Av
ProTech Heat Fab
FST3 & 93PPLSTEE
FSDF3
FSHDT3 9321
N/A 7000TUBE
17