HAMWORTHY HEATING LTD
Page
DORCHESTER DR-SE
500001062/D
12
peak demand.
If the kit is to be fitted to a heater which has also
been fitted with a gas solenoid valve (see 15.1) to
enable time clock control of the heater, the pump can
be wired to the same time clock so that during “off”
periods both pump and heater are shut down.
15.3.4 Maintenance
The pump manufacturer’s instructions should be fol-
lowed with regard to maintenance and servicing.
15.4 Living Space Installation
15.4.1 General
For heaters which are to be installed in a living
space, a combustion products discharge safety de-
vice must be fitted. The device can be supplied in the
form of a kit for either size of heater - HHL Part No.
563605150 - for site fitting during installation. It is
incumbent upon the installer / purchaser / specifier of
the heater for this use, that a kit is ordered and in-
stalled before the heater is put into service. The kit
comprises a thermal reset thermostat fixed at 79°C
with long capillary and sensor mounting bracket, pro-
tective sleeving for the capillary and a bridging cable
for the thermocouple circuit.
15.4.2 Assembly
Ensure the gas supply to the heater (if connected) is
turned off and electrical supply to other optional
equipment (if fitted) is isolated.
Remove top half of burner cover by lifting upwards
and pulling outwards. Locate the overheat safety
device and its mounting bracket. Unscrew the black
cover knob together with the mounting nut and re-
move overheat device. Trace back the two piece
thermocouple and ensure the lead to the pilot burner
is connected to terminal 1 of the overheat device.
Disconnect the second thermocouple lead to the gas
control valve at the overheat device, select the bridg-
ing cable from the kit and attach one end to spade
terminal 2 of the overheat device. Remount the over-
heat device to the underside of the bracket using the
right hand hole and with the body of the overheat
device to the right of the hole.
Tighten securing nut and replace cover knob.
Select the combustion products discharge thermo-
stat from the kit, remove the cover knob and secur-
ing nut and mount the thermostat adjacent to the
overheat device using the left hand hole in the
bracket and with the terminal connections facing for-
ward.
Tighten securing nut and replace cover knob.
Connect the loose end of the bridging cable to termi-
nal 1 of the thermostat and the thermocouple lead
from the gas control valve to terminal 2.
Carefully unwind sufficient capillary of the combus-
tion products discharge thermostat to reach the
draught diverter at the top of the heater.
Remove the bracket attached to the sensing bulb (if
fitted) and slide protective sleeving over sensing bulb
and capillary.
Locate the two holes drilled one above the other on
the sloping face of the draught diverter and rotate
diverter to reposition them approximately in line with
the gas control valve.
Remove the two screws from the sensing bulb
bracket, centrally position the bracket on the bulb
and with the smaller bracket holes to the rear, posi-
tion the bracket inside the draught diverter and se-
cure with the two set screws through the diverter.
The sensing bulb’s final position should be horizon-
tal, just under the lip of the diverter.
Position the capillary and sleeving down the casing
and coil excess capillary at the thermostat end. Refit
top burner cover and allow capillary to pass through
the slot on the left hand side.
Commission heater as detailed in Section 12.0.
15.4.3 Control
The combustion products discharge thermostat is
wired in series with the overheat safety device (limit
thermostat) on the thermocouple circuit. Should a
blockage or a severe draught occur in the flue, whilst
the heater is operating, the products of combustion
will spill from the draught diverter and pass over the
temperature sensor.
Once a temperature of 79°C is detected, the thermo-
stat will activate, breaking the thermocouple circuit
and shutting down the heater, both main flame and
pilot. The thermostat will reset automatically as the
temperature of the flue sensor reduces but the
heater requires manual intervention to relight the
pilot (see Section 12.0 of this manual for lighting up
instructions).
On relight, check for spillage with a smoke trace (sse
BS 5440 Part 1). If the blockage persists, the heater
will again shut down. The flue system should be thor-
oughly examined and the root cause of the problem
corrected.
No additional electrical supply is required for the op-
eration of the combustion discharge safety device
since it is connected to the millivolt thermocouple
circuit and no alarm signal can be added
In an alarm is required, it is suggested that a flame
failure alarm kit is added (see Section 2.2.4 and
