Xylem EPR IM Electric heater-circulator unit EPR (obsolete) - Manual (Page 19)

19
Instruction manual Laing Electric heater circulator unit
www.lainginc.com
Electronic means to prevent dry running
The Electric heater-circulator can only be operated when it is filled with water
and the circulator is running.
To protect the heating elements when the Electric heater-circulator is ac-
cidentally switched on without being filled with water, or when there is still a
lot of air in the system, the control system has electronic dry run protection,
which turns the heating elements off and gives a warning via the LED’s when
the temperature rises too fast.
In this case the red LED lights up, the yellow stays switched off. To reset
the system, the unit has to be switched off and then on. If the temperature
of the heating elements has fallen below the maximum temperature allowed
by the constant temperature control after the unit has been switched off, the
heater can be activated again. If the temperature is still too high, the unit has
to stay off until the heating elements have cooled down. Of course, the unit
has to be filled with water and the air has to be vented. (See chapter “Filling
of the system”).
The electronic dry run protection safeguards the safety temperature limiter
since in a dry run it could be permanent damaged. When the Electric hea-
ter-circulator is turned on and off several times after the electronic dry run
protection was activated, the safety temperature limiter can nevertheless be
damaged. Therefore, after the dry run protection was activated the system
first has to be filled with water and the air has to be vented before the unit is
switched on again.
Circulator operation control
To avoid the possibility that the heating elements could be switched on while
the circulator is not running, the control is equipped with a circulator operation
control. This means, that each time before the heating elements are turned
on, the control checks whether the rotor of the circulator is rotating. If the rotor
is blocked by dirt or if the bearing of the circulator is totally worn, the control
recognizes it and the heating elements will not be switched on.
In this case the circulator will be energized for about one minute. The con-
trol then tests again whether the rotor is rotating or not. If the rotor still does
not rotate, the same procedure is repeated ten times. If the rotor still does
not rotate, the control signals malfunction, which is indicated by the blinking
of the red LED and shining of the yellow LED.
In this case the circulator has to be removed to find the cause for the
malfunction. (See also chapter “Replacement of the circulation pump”).