Viessmann VITOGAS 100 GS1 series Installation Instructions Manual page 16

Connections
Venting Connection
Vent damper installation
If boiler is sold with a vent damper
(packaged separately), the vent damper
must be installed on the boiler to meet
minimum efficiency standards.
The vent damper must be field installed
on the boiler. Read the vent damper
manufacturer's instructions before
installing the vent damper.
The closing and opening action of the
vent damper is driven by a motor.
Spring action is not used to move the
vent damper blade. Do not force vent
damper blade by hand. Forcing the vent
damper blade by hand will damage the
motor. To observe the vent damper
blade movement, turn thermostat up
and down after vent damper has been
installed. Vent damper blade must be in
open position when burner is firing.
The vent damper must be installed as
illustrated below. Ensure that damper
blade rotates freely and is not
obstructed in any way. Read and save
the vent damper manufacturer's
instructions packaged with the vent
damper.
.
Molex connector
Strain relief
Boiler strain relief openings
16
(continued)
1. Review step 4 in subsection entitled
"Boiler wiring" on page 11.
2. Attach Molex female connector of
vent damper cable to counter male
connector on vent damper motor.
Use supplied plastic strain relief on
vent damper cable and metallic strain
relief on vent damper motor to secure
the cable.
There are no serviceable parts on the
vent damper. Defective vent dampers
must be replaced.
If a side wall vent system is used, the
vent damper must not be installed.
Refer to separate side wall vent system
instructions for series boiler. The side
wall vent system must be purchased
separately.
Sequence of operation with vent
damper:
1. Thermostat calls for heat.
2. Vent damper blade opens.
3. Pilot sparks and ignites.
4. Pilot is proven and main valve is
energized.
5. Main burner and pilot will continue to
operate until thermostat is satisfied.
Burner may turn off and on in
response to the adjustable high limit
aquastat setting during call for heat.
Should the vent damper become
defective:
1. Follow the vent damper
manufacturer's instructions to leave
the vent damper in the "Service" or
"Hold Open Damper" (Effikal) mode
by using the service switch on the
damper motor. Vent damper blade
should stay open and boiler should
operate normally.
2. If the procedure described above
does not work, remove vent damper,
install transitional piece of vent pipe,
disconnect and remove vent damper
cable from the 120 V / 24 V relay
module assembly. Connect jumper to
terminals 2 (orange) and 3 (yellow)
as illustrated below. Refer to wiring
diagrams. Boiler will operate without
vent damper.
Please note:
The "Effikal" damper can be field
replaced with a similar size "Field
Controls" damper.
Jumper connected to terminals 2 and 3
Removed vent damper cable