Repairs - Viessmann Solar EM-S1 Extension Installation And Service Instructions Manual

Solar EM-S1 Extension Installation / Service

Repairs

Check the function of the connected components by
means of an actuator test:
Heat generator installation and service
instructions
Legend
A Collector temperature sensor & (sensor type:
NTC 20 kΩ)
B DHW tank temperature sensor % (sensor type:
NTC 10 kΩ)
Checking the solar circuit pump at output P1
Characteristics of the circulation pump (see the following
chapter):
Pump always off:
– High limit safety cut-out has responded.
Reset the high limit safety cut-out.
– Output P1 faulty
Replace extension.
– Solar circuit pump faulty
Replace solar circuit pump.
Pump always on:
– PWM connection faulty
– Output P1 always live.
Replace extension.
Variable speed circulation pump with PWM control
Whenever a demand is present, a voltage of 120VAC
must always be applied to output P1. The pump speed
is governed by means of a control signal via PWM
connection.
If the PWM connection is interrupted, the circulation
pump must be switched off. If the circulation pump
runs at maximum speed when the PWM connection is
interrupted, an incorrect circulation pump has been
installed.
Checking the temperature sensors
1. Disconnect the plug of the relevant temperature
sensor from the extension. Check the sensor
resistance.
2. Compare the sensor resistance with the curve
(see the following diagram).
3. In the event of severe deviation, replace the sensor.
Troubleshooting
11