HAMWORTHY HEATING LTD
Page
DORCHESTER DR-SE
500001062/D
burner being shut off. Manual re-ignition of the pilot
flame is required to re-instate the heater into ser-
vice, once the temperature has dropped. Before
resetting, however, the installation should be in-
spected to trace and isolate the cause of the prob-
lem before any further firing takes place.
12.0 COMMISSIONING
12.1 System Checks
Before attempting to commission any heater ensure
that any personnel involved are aware of what ac-
tion is to be taken and begin by making the follow-
ing checks:-
a)
Flueway passages to the chimney are clear.
b)
Adequate ventilation exists in the boilerhouse
- refer to Tables 3 and 4.
c)
If the heater is installed in a living space, a
combustion products discharge safety device
is fitted.
d)
The water system is vented, fully charged
with water and ready to receive heat.
e)
The gas supply pipework is clear of any
loose matter, tested for soundness and
purged.
12.2 Heater Checks
On each heater, before attempting to light, check:-
a)
Draught diverter is currently installed on top
of the heater in an unmodified condition and
the flue retarders are correctly positioned
within each of the three fire tubes. The flue
has a removable section above the draught
diverter for maintenance.
b)
Heater is adjusted for the type of gas being
supplied. Gas supply is connected but turned
off at manual valve, unions are tightened,
test points are tight, burner is correctly posi-
tioned, the injector is tight and the pilot
burner is connected from the control valve.
Ensure lighting-up instruction sheet from in-
stallers kit is mounted on heater casing. Note
that protective plastic cover on casing should
be removed first.
c)
The thermostat sensing phial and overheat
safety device sensor are correctly and se-
curely positioned in the pocket. Remove
black cover knob from overheat safety device
and press reset button fully to ensure device
is reset. Check thermocouple is connected
and undamaged between the pilot burner,
overheat safety device and control valve.
d)
Piezo unit is fitted securely on the control
valve, the lead is undamaged, pushed fully
onto the spade connection and the spark
electrode is fitted correctly and undamaged.
e)
If heater is controlled by a time clock or addi-
tional electrical interlock, an electrically oper-
ated solenoid valve will be positioned in the
6
completed, open the main water supply valve, flush
the system and fill the heater. Open the hot water
taps and allow air to escape from the system. When
the system is free of air close the hot water taps and
check for leaks on all the water heater connections
including the drain valve, anode connections and
the inspection port flange. Before being taken into
use, the system should be cleaned and disinfected.
Refer to BS 6700.
10.0 GAS PIPE INSTALLATION
An Rc½ manual union gas shut-off valve is supplied
in the installers kit. The valve can either be fitted
direct to the gas inlet pipe or remote from the heater
but in close proximity to it. In either case ensure that
the valve is fitted with the union on the downstream
(gas control valve) leg of the pipework.
Connect the incoming gas supply to the manual gas
valve on each heater, observing the notes detailed
under Section ‘Gas Supply’, and conforming to the
requirements of BS6891. Before commissioning the
complete gas installation must be purged, inspected
and pressure tested for soundness.
NOTE:
Do not run the gas pipework across the front
of the heater at low level since this may prevent re-
moval of the burner assembly for maintenance and
avoid running the gas supply pipework across the
inspection door cover plate.
11.0 CONTROL SYSTEM
Automatic control of the heater centres around the
710 Minisit multi-functional gas control valve which
incorporates an integral thermostat with a range of
40 to 75°C. The thermostat action is purely me-
chanical, requiring no power supply and operating
on the principle of fluid filled bellows, capillary and
temperature sensing phial, the latter being located in
a pocket projecting into the heater. The functions of
the valve, including the temperature setting, are
controlled by a single knob with and interlocked
Piezo unit, which only operates when the control
knob is in the pilot gas position, to ignite the perma-
nent pilot. Pilot flame failure is detected by a two
piece thermocouple with a drop out time of 35 to 45
seconds. The two sections of a thermocouple are
joined by a connection to each side of an overheat
safety device (limit thermostat) located on a bracket
attached to the heater casing above the control
valve.
The overheat safety device is of the manual reset
type, the reset button being positioned beneath the
black covering knob. The sensing element for this
device is located in the same pocket as the control
valve sensor and is inserted second behind the lar-
ger phial. The overheat safety device is non-
adjustable and preset to operate at a temperature of
80°C. Should the device operate, the heater is im-
mediately shut down, gas to both pilot and main
