External Electrical Controls; Fitting The Weather Compensation Kit - Keston System s30 Installation And Servicing Instructions

2.18 EXTERNAL ELECTRICAL CONTROLS

Wiring External to the Boiler
The fuse rating should be 3A.
Wiring external to the boiler MUST be in accordance with the current
I.E.E. (BS.7671) Wiring Regulations and any local regulations.
Frost Protection
If parts of the pipework run outside the house or if the boiler will be left
off for more than a day or so then a frost thermostat should be wired
into the system.
The frost thermostat should be sited in a cold place but where it can
sense heat from the system.
Note. If the boiler is installed in a garage it may be necessary to fit a
pipe thermostat, preferably on the return pipework.

2.19 FITTING THE WEATHER COMPENSATION KIT -

CH OPERATION
The On and Off time control of central heating should be
controlled by a separate timer, connected to SL1 of the boiler.
During programmed On times the Central Heating Radiator
Flow Temperature is controlled by the boiler relative to the
Outside Temperature as shown in the diagram.
The Room temperature can be adjusted using the Central
Heating Temperature Control Knob on the boiler as follows.
Essentially rotating the knob clockwise increases the room
temperature and rotating the knob anti-clockwise decreases the
room temperature.
The Room Temperature Setpoint in the associated graph is
not directly related to the Actual Room Temperature but is the
Desirable Room Temperature during a programmed CH period.
This can be adjusted between 5 and 30 degrees by the
CH Potentiometer Knob on the Boiler when the Outside
Temperature Sensor is connected. The graph only shows
temperatures between 12 and 30 degrees for clarity.
Examples:
1. If the CH Potentiometer
Knob is set to display
22ºC on the Boiler
Display the Room
Temperature Setpoint will
be 22ºC and the curve 22
will be followed, indicated
by 11th curve in from
the left hand side. So as
the outside temperature
varies the Flow Setpoint
to the CH circuit will
increase and decrease
proportionally.
32
SECTION 2 - INSTALLATION
ROOM TEMPERATURE SETPOINT
EXAMPLE - Connection to Honeywell Evohome
(for additional information visit www.honeywelluk.com)
SUPPLIED AS STANDARD
2. If the CH Potentiometer Knob is rotated fully clockwise, the
Boiler Display will read 30ºC and the Room Temperature
Setpoint will be 30ºC hence the curve 30 will be followed.
3. If the CH Potentiometer Knob is rotated fully anticlockwise,
the Boiler Display will read 5ºC and the Room Temperature
Setpoint will be 5ºC. This is an unrealistic Room
Temperature Setpoint for a CH period during an ON time,
but it is calculated internally for managing Frost Protection
for the system based upon Outside Temperature.
DHW OPERATION
When the system is in a timed on period for DHW and the tank
stat is not satisfied, a call for heat will be generated on the
switched live input SL2 of the boiler.
This will ensure that Weather Compensation adjustment is
ignored at this time. The set point will be fixed at 70 degrees.
The demand is indicated on the display by a 'd' and the burner
on symbol as appropriate.
OUTSIDE TEMPERATURE
Installation and Servicing