STIEBEL ELTRON SOM 7 SI - Manual (Page 26)

SOM 7 SI
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Symptom Possible Cause and Remedies List
Operating control lamp flashes red. The
symbol is displayed and the symbol is flashing.
The indication channel of the relevent sensor
displays -88.8 instead of the temperature.
SOM unit is sensing a short circuit condition.
Measure the resistance between the two terminals to which 1.
the relevant sensor is attached. If it measures a resistance
close to zero continue to step 2. If it measures a resistance
within range of the above chart, call for service.
Disconnect the sensor wire from the terminals and measure
2.
the resistance between the two wires. If it still measures a
resistance close to zero continue to step 3. If it measures a
resistance within range of the above chart, there is a problem
with the connection from the sensor wire to the terminal.
This problem lies either with the sensor or the wire/connec-
3.
tions. In order to determine whether the problem lies with
the sensor itself, the sensor and its 4’ wire which was factory
installed must be disconnected from any extension wire and
its resistance must be measured. If, when the sensor is discon-
nected, the resistance is measured to be within the values of
the resistance chart the problem is with the extension wire/
connections.
Operating control lamp is off and screen is blank. SOM unit’s control board is not receiving power.
HAZARDOUS VOLTAGE PRESENT!
Measure the voltage between terminals 19 and 20. If the volt- 1.
age is close to the nominal voltage of 120 VAC, continue to
step 2. If the voltage is not correct, the problem lies with the
power supply to the unit.
Remove the unit’s can fuse and measure its resistance. If the
2.
resistance is close to zero, call for service. If infinite resistance
is measured, replace the fuse.
Collector is much hotter than the storage tank,
but the system’s circulator is not on. Compare the tank’s present temperature with its maximum 1.
setting (S MX). If the storage tank is within 4 degrees of this
setting the circulator pump will not turn on even if the switch
on temperature has been reached unless the System Cooling
Function (OCX) is turned on and the Maximum Collector
Temperature (CMX) has been reached.
Check to see if the
2. symbol is blinking. If this is the case the
system is in Emergency Shutdown Mode. Either the collector
sensor measured a temperature equal to or greater than the
Collector Emergency Shutdown Temperature (step 3), or the
store sensor measured a temperature of at least 205 °F (step
4).
If the system has reached the Collector Emergency Shut-
3.
down Temperature, the controller’s configuration needs to be
checked. Is the cooling function (OCX) set to on? Is there
a sufficiently large
ΔT between the Maximum Collector
Temperature (CMX) and the Collector Emergency Shutdown
Temperature (EM)? To get the system to exit emergency
shutdown mode the EM setting must be at least 30 °F greater
than the measured collector temperature.
If the storage tank has reached its emergency shutdown tem-
4.
perature (205 °F), the circulator will not turn on unless the
store sensor measures a temperature of 201 °F or less. This
parameter is not adjustable.