5
OPERATION MODES
Winter Conditions -
(Central Heating and Domestic Hot Water
required)
Set the mode knob (D) ‘
’ (winter).
The boiler will fire and supply heat to the radiators but will
give priority to domestic hot water on demand.
The domestic hot water preheat will operate with the preheat
knob (A) set to ‘
preheat on
’.
Summer Conditions -
(Domestic Hot Water only required)
Set the mode knob (D) to ‘ ’ (summer).
Set the central heating demand on the external controls to OFF.
The domestic hot water preheat will operate with the preheat
knob (A) set to ‘
preheat on
’.
Boiler Off
Set the mode knob (D) to ‘
boiler off
’. The boiler mains power supply
must be left on to enable frost protection (see Frost Protection).
PREHEAT - DOMESTIC HOT WATER
The domestic hot water heat exchanger within the boiler can
be kept preheated to provide faster delivery of hot water at the
tap. This is achieved by turning the ‘preheat on/off’ knob (A)
to ‘
preheat on
’.
The boiler will operate periodically for a few seconds to
maintain the domestic hot water heat exchanger in a preheated
condition. The average time period between operation is 90
minutes. This may vary considerably due to the surrounding
ambient temperature of the boiler. The boiler will operate
whenever there is a demand for domestic hot water.
If standard hot water delivery is satisfactory turn the knob (A)
to ‘
preheat off
’.
CONTROL OF WATER TEMPERATURE
Domestic Hot Water
The domestic hot water temperature is limited by the boiler
controls to a maximum temperature of 64
º
C, adjustable via
the domestic hot water temperature knob (B).
Approximate temperatures for domestic hot water:
Knob Setting
Hot Water Temperature (approx.)
Minimum
40ºC (104ºF)
Maximum
64ºC (147ºF)
Due to system variations and seasonal temperature
fluctuations domestic hot water flow rates/temperature rise
will vary, requiring adjustment at the tap : the lower the flow
rate the higher the temperature, and vice versa.
Central Heating
The boiler controls the central heating radiator temperature
to a maximum of 80
o
C, adjustable via the central heating
temperature knob (C).
Approximate temperatures for central heating:
Knob Setting
Central Heating Radiator Temperature (approx.)
Minimum
45ºC (113ºF)
Maximum
80ºC (176ºF)
For economy setting ‘ ’ refer to Efficient Heating System
Operation.
