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USING THE BURNER
The burner operates on a fully automatic basis. Turning on the main switch and control panel switch turns the burner
ON. Burner operation is governed by the controls described in “Description of Operation”.
The “shutdown” position is a safety position to which the burner sets itself automatically when some burner or system
components is operating improperly. It is therefore good practice to make sure that there are no anomalies before
“resetting” the burner. The burner can stay in the shutdown position indefinitely.
Shutdowns may be caused by transitory faults (a little water in the fuel, air bubbles in the piping etc.). In such cases the
burner restarts easily when reset. When, however, shutdowns occur repeatedly (3 - 4 times) do not attempt any more
restarts; check there is fuel in the tank and contact the local After-Sale Service to have the fault dealt with properly.
To reset the unit press the appropriate push-button.
MAINTENANCE
The burner requires no special maintenance. It is, however, good practice, at least at the end of the heating season, to
carry out the following tasks:
1) Remove and wash the filters, the nozzle, the diffuser disc and the ignition electrodes with solvents
(petrol, trichlorethylene, naphta). Do not use metallic objects to clean the nozzle (use wood or plastic).
2) Clean the photoresistances.
3) Have the boiler cleaned and, if necessary, the flue.
N.B.
The nozzle (or nozzles) must be replaced at least every two heating seasons. This may be necessary even more
frequently.
TWO-STAGE BURNERS: DESCRIPTION OF OPERATION
The two-stage burner always ignites with reduced fuel and air flow-rates (1st stage) and then, after a few seconds, runs
in full air and fuel flow work mode (2nd stage).
Second stage ignition requires consensus from the control box and control device (pressure switch and thermostat).
When running at full flow the unit will remain in this mode until pressure or temperature reaches control device (pressure
switch or thermostat) settings. The control device trips and extinguishes the second stage (fuel and air) when its setting
levels are reached. The burner then continues to operate with the first stage only.
The first stage is, on its own, not normally sufficient to maintain pressure or temperature at desired levels.
Therefore the latter falls until it reaches the level at which the second stage control device (pressure switch or
thermostat) restores total fuel and air flow-rates. The burner is shut down completely when, with only the first stage
burning, pressure or temperature reaches a level that trips the operating device (pressure switch or thermostat).
The unit re-ignites automatically when pressure or temperature falls below the levels to which the pressure switch or
thermostat has been set.
N.B.
It is usually inadvisable to connect up a burner for two-stage operation when used on a boiler that produces
hot water for heating purposes. In this case the burner works (sometimes for extensive periods) on a single
stage only and the boiler is insufficiently heated; consequently combustion fumes exit at a too low tempera-
ture (less than 180° C), giving rise to soot at the flue. When the boiler is insufficiently filled the formation of
acid condensate and soot in the boiler becomes highly probable, leading to rapid clogging and corrosion of
the boiler itself. When the two-stage burner is installed on a boiler providing hot water for heating purposes it
must be connected so that it gives full-flow operation with both stages and complete shutdown (without
passing over to single-stage operation) on attainment of set temperature. To obtain this operating mode the
second stage thermostat is not installed and a direct “jumper” connection (bridge) is effected between the
respective control box terminals.This solutions means that only the burner’s ability to ignite at low flow-rates
(smooth ignition) is employed; this condition is indispensable for boilers with pressurized combustion
chambers yet is also useful with standard boilers (negative pressure combustion chamber). Burner control
(ignition or shutdown) is subordinate to the usual working or safety thermostats.
