Laars NEOTHERM NTV, Service Manual, Page: 58 / 118

48
Service Manual - NeoTherm 500
Checking the DHW Sensor
The System sensor is mounted in the circulating loop, and provides the input for the
CH (Central Heating) function. This type of sensor can fail in either an “open” or
“shorted” condition, or may become inaccurate.
On a unit with the current user interface -
Check the line on the display for “LL OPER TEMP.” If the sensor is operating normally,
the unit will display a temperature on this line. The display will indicate an open sensor
as “OPEN”, and a shorted sensor will be shown as “SHORT.”
On a unit with the original user interface -
Check the line on the display for “LL.” If the sensor is operating normally, the unit will
display a temperature on this line. If the sensor is not working, or is disconnected, the
display will present three dashes: “- - - .”
To check the sensor for accuracy, see Section B32.
The DHW sensor is mounted in the indirect hot water tank, and provides the input
for the DHW (Domestic Hot Water) function. This type of sensor can fail in either an
“open” or “shorted” condition, or may become inaccurate.
On a unit with the current user interface -
Check the line on the display for “DHW TEMP.” If the sensor is operating normally, the
unit will display a temperature on this line. The display will indicate an open sensor as
“OPEN”, and a shorted sensor will be shown as “SHORT.”
On a unit with the original user interface -
Check the line on the display for “DHW.” If the sensor is operating normally, the unit
will display a temperature on this line. If the sensor is not working, or is disconnected,
the display will present three dashes: “- - - .”
To check the sensor for accuracy, see Section B32.
B26
Checking the System Sensor
B27