Unigas HTP2000 Installation Manual page 25

Keys
S1 Main switch (0=Off, 1=GAS, 2=OIL)
S2 Reset pushbutton for control box
S3 CMF switch (0=stop, 1=low flame, 2=high flame, 3=automatic) - fully modulating burners only
D Gas proving system reset pushbutton (only for burners with Siemens LDU11 provided)
B1 Lock-out LED
B2 Hi-flame operation LED
B3 Lo-flame operation LED
B4 "Ignition transformer operation" LED
B5 "Fan motor overload tripped" LED
B6 Stand-by signalling lamp
G1 Gas valves EV2 operation signalling lamp
G2 Gas valves EV1 operation signalling lamp
G3 Gas pressure switch signal lamp
G4 Gas proving system lockout signalling lamp
O5 Oil valve EVG operation signalling lamp
A2 AZL..
Gas operation
Check the gas feeding pressure is sufficient (signalling lamp G3 on).

the gas proving system test begins; when the test is performed the proving system LED turns on. At the end of the test, the burner

staring cycle begins: in case of leakage in a valve, the gas proving system stops the burner and the lamp B1 turns on.
NOTE: if the burner is fitted with Dungs VPS504, the pre-purgue phase starts once the gas proving system is successfully performed.
Since the pre-purgue phase must be carried out with the maximum air rate, the control box drives the actuator opening and when the
maximum opening position is achieved, the pre-purge time counting starts.
At the end of the pre-purge time, the actuator drives the complete closing (ignition with gas position) and, as this is achieved the

ignition transformer is energised (LED B4 is on); the gas valves open.
Few seconds after the valves opening, the transformer is de-energised and lamp B4 turns off.

The burner is now operating, meanwhile the actuator goes to the high flame position and, after some seconds, the two-stage ope-

ration begins; the burner is driven automatically to high flame or low flame, according to the plant requirements.
Operation in high or low flame is signalled by lamp B2 on the frontal panel.
Fig. 14 - Burner control panel
B2 B3 B4
B5
O5
G1
G4
G2
G3
S2
B1
B6
S1
25
PART III: OPERATION
A2
S3