9
1.6
BOILER OPERATION
The boiler operating mode is controlled by the selector switch
on the control panel. When set to winter (
) it will operate in
the Domestic Hot Water and Central Heating modes. For
Domestic Hot Water only the selector switch should be set to
summer (
). Domestic hot water supply always takes
priority over central heating. If a demand for hot water is
required during a central heating period, the boiler will
automatically switch to hot water mode until the demand is
satisfied.
1.6.1 Central Heating mode
If there is a call for central heating the pump will start to
circulate the primary heating water and the fan will run at full
speed; once the air pressure switch has been proved the
burner will light. The burner output then automatically adjusts
to suit the system demand; as the temperature of the heating
water in the boiler approaches that set by the adjustable
central heating control knob the burner output is reduced.
When this set temperature is reached, the burner
extinguishes and the fan stops. The pump continues to run for
30 seconds to prevent residual heat build up in the boiler. The
burner will not relight for 3 minutes unless there is a demand
for domestic hot water during this period.
1.6.2 Domestic Hot Water mode
The pump does not operate on a DHW demand, the fan runs
and once the air pressure switch has proved the boiler will
light.
The burner output then automatically adjusts to suit the
demand required to raise the temperature set by the
adjustable domestic hot water control knob.
When the hot water demand has been satisfied, it passes to
the operation in C.H., if the selector is set to winter (
) and
there is a C.H. demand, otherwise the burner will extinguish.
1.5
INTERNAL VIEW
Fig. 3
KEY
1 Control panel
2 Burner
3 100°C safety stat
4 C.H. sensor (SM)
5 Fan
6 Air pressure switch
7 Bithermal exchanger
8 Combustion chamber
9 D.H.W. sensor (SS)
10 Gas valve
11 Manifold with intakes
Summary of Contents for Format B
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