Indicator Neons; Overheat Thermostat; Pressure Relief Valve; Frost Thermostat - Alpha CD18S User Instructions

4. INDICATOR NEONS

When neons A (red), B (red), C (yellow), D (green) are illuminated, the following conditions apply:-
Neon
D Illuminated continuously - Electricity supply to the boiler is on.
C Illuminated continuously - Burner is alight.
A Flashing on and off - Temperature sensor fault, contact your Service Engineer.
B Flashing on and off - Overheat thermostat has operated. Rotate selector switch to the reset position (3) to reset. If this continues
to happen, contact your Service Engineer.
B Illuminated continuously - Burner has failed to light. Rotate selector switch to the reset position (3) and the ignition
sequence will restart after a delay of about 30 seconds.
A and B Flashing on and off at the same time - Blocked flue or fan fault, contact your Service Engineer.
A and B Flashing on and off alternately - System pressure is very low and re-pressurisation is required.
A Flashing and B Illuminated continuously - Pump fault or restricted flow.
Note: Do not hold the selector switch in the reset position (3) for more than 2 or 3 seconds.

5. OVERHEAT THERMOSTAT

This thermostat automatically switches the boiler off in the unlikely event of the boiler overheating. When the thermostat operates,
the red neon (B) flashes on and off. Rotate the selector switch to the reset position (3) and the boiler will relight.
If this continually happens, contact your Service Engineer.

6. PRESSURE RELIEF VALVE

If the central heating system overheats and steam or water is discharged from the pipe connected to this valve, turn the boiler off
and contact your Service Engineer. Your Installer should have shown you where this pipe terminates, usually outside your dwelling.

7. FROST THERMOSTAT

The boiler has a built-in frost thermostat, which automatically operates the boiler if the water temperature falls below 8°C,
providing the electrical supply is on and the selector switch is set to position (1) or position (2).
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LIGHTING INSTRUCTIONS

Refer to Fig. 1 for boiler controls.
1. Ensure the following:-
a. Electrical supply to the boiler is off.
b. All heating controls and thermostats are set to OFF or minimum position.
c. All isolation valves at the bottom of the boiler are in the open position (slot on the spindle in line with the valves i.e.
d. The gas and water supplies are on at the mains.
e. The heating system pressure is within the green band as shown by the pressure gauge.
2. Switch on the electrical supply to the boiler.
3. Set any room thermostats to maximum and ensure that any clock is in an 'on' position.
4. Set the selector switch to position (2) and turn the heating thermostat fully clockwise. The main burner will light and the
boiler will provide central heating.
5. Set the boiler thermostats, clock, external controls i.e. room thermostat to your chosen settings and the boiler is ready to operate.
To turn the central heating off i.e. in Summer:- Set the selector switch to position (1).
To turn the boiler off for short periods:- Set the selector switch to position (1).
Note: In this position the pump will automatically operate for 5 minutes in every 24 hours. If the water temperature falls below
8°C the built-in frost thermostat will operate the boiler automatically until the temperature of the water in the heating system has
been raised.
To turn the boiler off for longer periods:- Switch off the electrical supply to the boiler. If required, all supplies i.e. gas, water
and electricity may be turned off at the mains. If there is any possibility of the boiler being left during frost conditions, then the
boiler and system should be drained and a label attached to the boiler drawing attention that the system has been drained. If
this is required, contact your Service Engineer.
Alpha CD18S/24S/30S
).
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