4
DMG 973
INSTALLATION INSTRUCTIONS AND MAINTENANCE
1. Important notes
– The controls must be installed by qualified personnel
only. The relevant national regulations have to be
observed.
– On commissioning the wiring has to be carefully check-
ed according the appropriate diagram, Incorrect wiring
can damage the unit and endanger the installation.
– The fuse rating has to ensure that the limits specified in
TECHNICAL DATA will not be exceeded. If these precau-
tions are not observed, the effect of a short circuit can
cause severe damage to the control and installation.
– For safety reasons a minimum of one control shutdown
per 24 hours has to be observed.
– Disconnect the mains before the control box is plugged
in or out.
– The control box is a safety device and must not be
opened!
2. Function control
For safety reasons the flame detection system should be
tested on commissioning the installation as well as after a
service or longer shut-down.
a) Start-up with closed gas valve
– After lock out safety time is over the unit has to go into
lock out mode!
b) Normal start-up, when burner is running, close gas valve
– After loss of flame, the control box has to go into
lockout mode
c) Normal start-up, during pre-purge or operation, interrupt
the air proving switch
– The control box has to perform a lockout immediatly
d) Bridged air proving switch before start
– the fan motor switches on for approx. 2 - 3 secs,
followed by a lockout. After 10 secs., this quick
lockout is resetted by the control box and a second
start attempt follows (fan motor switches on for approx.
2 - 3 secs.). A standard lockout appears if the air
proving switch (LW) contact is still in it’s closed
position (e.g. welded contacts). Has the air proving
switch (LW) changed to it’s open position in the
meantime (e.g. by a run down motor), a normal start
sequence follows.
3. Fault finding
The built-in information system facilitates the trouble shoot-
ing in the case of problems occurring during start-up or
during operation.
A list of possible lock out messages can be found in
APPLICATION FEATURES chapter 1.2.
Please note:
The control box is locked in lock out mode
and the reasen for the lock out is displayed
until the control box is reset, either by an
internal or external reset (see also subject “3.
Lock out and reset").
Removing the control box from its wiring base or by
interrupting the supply line may
not
reset a lock out. There-
fore, by applying power, the fan motor switches on for 2-3
secs. before the control box goes to lock out again and the
cause of the last lock out.
Error
Possible fault
Burner not working
- Thermostat circuit open
- Faulty electrical wiring
- Mains voltage < 187 V (< 80 V)
- Terminal A continuously on
power (e.g. terminal A is used as
a support terminal)
Fan motor starts for a short
- Control box has not been reset
period of time, control box
- Air proving switch not in open
goes to lock out
position
Control box locks out
- Air proving switch has not
during pre-purge
closed within 60 secs.
- Air proving switch has re-opened
Control box locks out
- Air proving switch open
at the end of pre-purge
- Flame signal (stray light)
Burner starts,
- No ignition or no fuel
flame
not
established
after safety time,
lock out
Burner starts,
- No or too low flame signal (flame
flame established,
does not stick, bad insulation of
after safety time,
the ionisation probe, bad connec-
lock out
tion to frame ground)
- Insufficient light on IRD
- Sensitivity adjustment
too low on IRD