18
Operating Instructions
Operating Instructions
PLEASE READ: Important Notes for the
Boiler Attendant
Starting up after cleaning the boiler or
a Summer shut down.
Ensure that fuel lines are fully purged and that fuel
is available at the burner at the correct pressure and
temperature.
That spirals/retarders if supplied are refitted
On a gas-fired boiler, if the boiler has not been run for some time,
or if a fuel supply pipe has been disconnected, purge the piping
via the bleed nipple up stream of the burner to ensure that a
gas/air mixture is avoided.
On an oil-fired boiler using class D oil in conjunction with a single-
pipe supply system, ensure that air is bled from the system if the oil
pipe has been
disconnected.
Ensure fuel supply valves are open. Where a pump is incorporated in
an oil fuel supply system, ensure the pump is switched ON. Check all
switches, e.g. time switch, and thermostats are in the ‘calling’ for heat
condition. Switch ON electrical supply to the burner at the main switch.
Switch the control panel mounted switch to ON. The burner control
box should now monitor the burner through its prescribed sequence
to reach 'main flame on'.
Normal Running
The boiler will switch on/off under the dictates of the control thermostat. The
boiler temperature at any particular moment can be seen from the boiler
thermometer.
Allow the boiler to reach its set temperature and then check the
burner flame through boiler door sight orifice; the flame should
extend well into the combustion chamber. Also check the flame
characteristics at the burner through the burner inspection
window. If any deterioration is noted, the heating engineer should
ensure the necessary action is taken.
These instructions are the minimum necessary to enable an
operator to start, run and stop the boiler.
They cover also the simple routine servicing procedures
necessary. Except where specifically noted, they are applicable
irrespective of the fuel used - gas or oil - BS class D (35 sec).
If the heating system designer or installer has prepared operating
and maintenance instructions specifically for the whole plant,
those instructions should be referred to in the first instance.
Instruments and Controls
Instruments are generally mounted at the top front of the boiler.
A boiler flow water thermometer will always be present, an
altitude gauge may also be provided.
The basic controls for any boiler will be:-
a) A sequence-control box (mounted on the burner) which
automatically governs the firing sequence of pre-purge,
ignition, pilot or reduced start, and provides for safety
lock-out in the event of flame failure or other unsafe condition.
This control box will have advisible indication of lock out and a
manual-reset button for use in the event
of flame failure.
b) A control thermostat which allows adjustment of the boiler
flow temperature is fitted behind the instrument panel facia to
discourage unauthorised adjustment after it has been set by
the commissioning engineer.
c) A safety-limit thermostat which comes into operation should
the control thermostat fail to shut the burner down.The limit
stat is usually set at 10
o
C above the control thermostat’s
maximum setting. No automatic control may be interfered with
by the boiler attendant but must be adjusted only by a qualified
Service Engineer.
There may be special burner controls equipment or
additional controls to be integrated with the standard
burner control equipment. The function and setting of
these will be covered by the suppliers e.g. BMS.,
sequence controls high and low pressure switches and
water level controls, associated with independendently
pressurised systems.
NOTE: A gas/air mixture is dangerous as it
will explode if subjected to a spark.
Sequencing of boilers under BMS control.
When a bank of boilers are sequenced to operate under the dictates of a BMS control system, it is very
important that on-line boilers are "properly" matched to the available heating load at any one time.
This will avoid too frequent cycling of the burners as they stop and start (introducing cold pre & post purge
air into the boiler each time this happens).
Over time this can result in the boilers suffering from thermal shock and premature failure of the pressure
parts.
August 2014