Viessmann FB2B Installation And Service Instructions Manual page 125

Repairs
(cont.)
Checking the solar control module fuse
A
1. Switch OFF the power.
Extension kit for heating circuit with mixer
Checking the setting of rotary selec-
tor S1
The rotary selector on the PCB of the
extension kit defines the assignment to
the relevant heating circuit.
Heating circuit
Heating circuit with
mixer M2 (heating cir-
cuit 2)
Heating circuit with
mixer M3 (heating cir-
cuit 3)
2. Check fuse A in the solar control
module (see connection and wiring
diagram).
Checking the rotational direction of
the mixer motor
After being switched ON, the boiler
implements a self-test. During this, the
mixer is opened and closed again.
Rotary
selector S1
setting
2
4
Troubleshooting
125