User's
Instructions
Alpha CD50
Wall Mounted, Fan Assisted, Room Sealed, Gas Fired,
High Efficiency, Condensing Combination Boiler with
Unvented Hot Water Storage
For Technical help or for Service call ...
ALPHA HELPLINE Tel: 0870 3001964
website:www.alpha-innovation.co.uk
Nepicar House, London Road,
Wrotham Heath, Sevenoaks,
Kent TN15 7RS
British Gas
Service Listed
Alpha CD50 G.C. No. 47 532 24
For use with Natural Gas only
Leave these instructions with the User
1 DESCRIPTION
The Alpha CD50 is a wall mounted, high efficiency, fan assisted, room-sealed, condensing combination boiler - incorporating a
52 litre unvented hot water storage cylinder. It provides central heating and domestic hot water at mains pressure.
As supplied, the boiler is suitable for central heating systems requiring between 6.3 and 29.7 kW (21 500 and 101 430 Btu/h).
It will provide central heating (as required) during the 'on' times set on your clock (if fitted). Hot water is always available
whenever a hot tap is opened.
2 USER CONTROLS
Pull the control panel cover forward and down to gain access to the controls.
System
Pressure Gauge
2
1
04
bar
Indicator
Neons
3
Selector Switch
Domestic
Hot Water Thermostat
OFF
0
A
B
C
D
1
2
RESET
3
SELECTOR THERMOSTAT THERMOSTAT
1
9
8
5
7
6
Central
Heating Thermostat
2
3
4
1
2
9
8
3
4
5
7
6
Clock (if fitted)
CD50
Fig. 1
3 BOILER CONTROLS
1. CENTRAL HEATING THERMOSTAT
This thermostat controls the temperature of the water leaving the boiler for the heating system. For maximum efficiency from
the boiler the thermostat should be left at number 5 or 6 as shown in Fig. 1. If lower heating temperatures are required, turn the
thermostat anti-clockwise. If higher temperatures are required, turn the thermostat clockwise.
2. DOMESTIC HOT WATER THERMOSTAT
This thermostat controls the temperature of the domestic hot water leaving the boiler. For maximum hot water temperatures the
thermostat should be left at maximum. If lower temperatures are required, turn the thermostat anti-clockwise.
Note: It is recommended that the thermostat is always set between settings 7 and 9.
3. SELECTOR SWITCH
This control allows the boiler to provide central heating and hot water or hot water only. The '0' position will turn the boiler off.
4. PRESSURE GAUGE
This indicates the central heating system pressure. It should always be within the green band when cold, increasing slightly
when hot.
If the pressure falls below the green band, ie red area, the system needs re-pressurising. Contact your Installer to have the
system checked and pressurised.
Alpha CD50
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5. 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.
B Flashing on and off - Overheat thermostat has operated. Rotate selector switch to the reset position (3) to reset.
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.
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 to 3 seconds.
6. 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.
7. PRESSURE RELIEF VALVES
If the central heating or hot water system overheats and steam or water is discharged from the pipe connected to the valve or from
the tundish, turn the boiler off and contact your Service Engineer. Your Installer should have told you where these pipes terminate.
8. 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
(1) or (2).
4 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 (flats on the spindle in line with the valves).
d. The gas and water supplies are on at the mains.
e. The heating system pressure is within the green band as shown on the pressure gauge.
2. Turn the heating and hot water thermostats fully anticlockwise to 0 and set the selector switch to 0.
3. Switch on the electrical supply to the boiler.
4. Set any room thermostats to maximum and ensure that any clock is in an 'on' position. Refer to section 8, if a clock is fitted
in the boiler control panel.
5. Set the selector switch to
6. Turn the hot water thermostat fully clockwise. The main burner will light and the hot water storage cylinder will be heated.
After approximately 7 minutes (from cold) the boiler will be ready to provide hot water and the burner will go out.
7. Set the selector switch to
burner will light and the boiler will provide central heating.
8. 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
To turn the boiler off for short periods:- Set the selector switch to
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:- Set the selector switch to 0. 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.
(hot water only).
(central heating and hot water) and turn the heating thermostat fully clockwise. The main
(hot water only).
(hot water only).
Alpha CD50
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5 BOILER OPERATION
The operating sequence of the boiler is controlled by the selector switch on the control panel. With the switch set to (hot water
only) the boiler will only operate to provide domestic hot water, ideal for Summer use when central heating is not required.
Setting the selector switch to
hot water.
If the boiler is operating to provide central heating and a hot water tap is opened, the boiler will give priority to provide hot water.
Such an interruption in the central heating should not be noticed by any reduction in room temperature.
Note: If a clock is fitted to the boiler, it will only control the operating times of the central heating. Hot water will always be
available when a tap is opened.
When the boiler is set to provide both central heating and hot water, it will respond to a demand for heat in the following sequence:The pump will start, the fan will start and the main burner will light.
The output of the burner is automatically controlled to suit the system demand.
When the temperature of the heating system water in the boiler reaches that set by the thermostat or the room thermostat is
satisfied, the main burner is turned off and after approximately 50 seconds the fan stops. The pump will continue to run to
remove any residual heat from the boiler.
When a hot tap is opened, hot water is provided instantly. When the temperature of the water in the storage cylinder falls to below
that set by the thermostat, the pump will start, the fan will start and the main burner will light to reheat the water in the storage cylinder.
Note: When the hot water temperature falls below approximately 48°C, the flow of hot water from the boiler is reduced. This
allows hot water to be supplied continuously until the water in the storage cylinder has been reheated.
The supply of hot water is instantaneous at the boiler, but the time taken to reach a tap will depend on the length of the pipe between
the tap and the boiler.
The flow of water to the hot taps will depend on the mains water pressure.
(central heating and hot water) the boiler will operate to provide both central heating and
6 USING A SHOWER
Thermostatic or pressure equalising type - When using these types of shower set the boiler domestic hot water thermostat
to maximum. The shower should then maintain a relatively constant temperature.
Manual bath mixer type shower - When using this type of shower set the boiler domestic hot water thermostat to setting 7,
This should avoid excessive temperatures at the shower.
Note: If you get unacceptable temperature variations with this type of shower, then a thermostatic or pressure equalising type
should be used.
7 IMPORTANT NOTES
1. BOILER LOCATION
Always ensure the following clearances are available around the boiler:-
Top: 220 mm, Bottom: 250 mm, Sides: 10 mm, Front: 450 mm
If the boiler is installed in a cupboard or compartment, ensure that all ventilation openings are clear. Do not store any other articles
in the cupboard containing the boiler and never place any clothing or combustible material on or near the boiler or flue pipe.
2. FLUE TERMINAL
The terminal on the outside wall must not be allowed to be obstructed. If it is damaged, in any way, turn the boiler off and
contact your Service Engineer.
Note: The Alpha CD boilers are high efficiency condensing boilers and when operating vapour will be emitted from the terminal.
This is safe and quite normal.
3. MAINS FAILURE
In the event of an electrical supply failure the boiler will not operate. When the supply is restored, the boiler will return to normal
operation. Remember to reset the clock when the supply is restored.
If the mains water supply fails, there will be no hot water from the taps. The boiler will continue to provide central heating.
4. ADDITIONAL BATHROOM FITTINGS
Any equipment such as mixing valves, showers, bidets etc. must be designed to operate at mains water pressure. Contact your
local Water Authority for advice when considering purchasing such items.
Alpha CD50
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5. CLEANING
Use only a damp cloth and mild detergent to clean the boiler outer casing. Do not use abrasive cleaners.
6. SERVICING
To maintain efficient and safe operation of your boiler, routine annual servicing is essential.
For advice on servicing contact the Alpha Helpline: 0870 3001964.
7. GAS LEAK
If a fault or gas leak is suspected, turn off the gas supply. Do not touch any electrical switches, do not smoke and extinguish all
naked flames. Contact your local Gas Region immediately.
8. ELECTRICAL SUPPLY
The boiler requires a 230/240 V ~ 50 Hz supply, fused at 3 A if a 13 A 3-pin plug is used or a 5 A fuse if any other type of plug is used.
To connect a plug:-
The colour of the wires in the mains lead of the boiler may not correspond with the coloured markings identifying the terminals
in your plug. In this case proceed as follows:-
The wire coloured green and yellow must be connected to the terminal in the plug that is marked with the letter E, or by the
earth symbol , or coloured green or green and yellow.
The blue wire must be connected to the terminal which is marked with either the letter N or coloured black.
The brown wire must be connected to the terminal which is marked with the letter L or coloured red.
THE APPLIANCE MUST BE EARTHED.
8 GAS SAFETY REGULATIONS
Current Gas Safety (Installation and Use) Regulations:It is the law that all gas appliances are installed and serviced by a competent person, i.e. CORGI registered personnel.
Failure to install or service appliances correctly could lead to prosecution. It is in your interest and that of safety to ensure
compliance with the law. The manufacturer's instructions must not be taken in any way as over-riding statutory obligations.
The Benchmark Checklist must be fully completed by the installer on installation and commissioning of the boiler. The
Benchmark Checklist is shown in Section 12 of the Installation and Servicing instructions. All CORGI registered installers
carry a CORGI ID card and have a registration number. Both should be recorded in the Checklist. You can check your
installer is CORGI registered by calling CORGI on 01256 372300.
9 CLOCK (if fitted)
The clock allows you to set the times at which the boiler will operate to provide central heating. It does not affect the supply of
domestic hot water, which is always available whatever the setting of the clock.
1. TO SET THE TIME
Turn the outer dial clockwise to set the clock hands to
the correct time.
(Ensure the time indicator corresponds with the correct
time on the 24hr dial as shown in Fig. 2,
e.g. 3.00pm = 15 not 3).
NOTE: Do not rotate the dial anti-clockwise
2. TO SET THE ON/OFF PERIODS
Select the ON times by pushing the tappets to the
outside.
Select the OFF times by pushing the tappets to the
inside.
Fig. 2 shows the clock set as follows:-
ON 3.00pm to 10.00pm (15 - 22)
OFF 10.00pm to 5.00am (22 - 5)
ON 5.00am to 8.00am (5 - 8)
OFF 8.00am to 3.00pm (8 - 15)
Fig. 2
Alpha CD50
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3. MANUAL SWITCH
The clock has a manual On/Off switch which operates as follows:-
Mid position Heating On/Off as set by the tappets
Position I (right) Heating On continuously
Position 0 (left) Heating Off continuously
10 F AULT FINDING FOR THE USER
If you experience a problem of no heating or hot water, try to solve the problem by following the simple checks below before
calling out a service engineer.
Pull the controls panel cover forward and down to gain access to the controls.
If any of these lights are on or flashing,
rotate the selector switch to RESET (position 3)
Is needle within or above
the green band ?
If not - See A
2
3
1
04
bar
Turn selector to
(position 1)
OFF
0
A
B
C
D
1
2
RESET
3
SELECTOR THERMOSTAT THERMOSTAT
See D
Turn to
maximum
1
2
9
3
4
8
5
7
6
1
2
9
3
4
8
5
7
6
Clock (if fitted)
CD50
If this light is not on
See B
Then turn selector to
This light should illuminate
If not - See C
- Where applicable, refer to the label on the inside of the hinged cover for guidance on
A
(position 2)
Open a hot tap fully and this light should illuminate
after approximately 1 minute
If no hot water - See E
repressurising the system. Or contact your installer. Or
- Check that the electrical supply to the boiler is on. If so
B
- Check that all controls are calling for heat, i.e. room thermostat, clock. If so
C
- Check that the gas supply is on. If the light continues to come on after resetting
D
- Contact the Alpha Helpline
E
Ring the
Alpha Helpline Service
Tel: 0870 3001964
You will be asked
the Serial No. of your
boiler when you ring.
The Serial No. of the
boiler is on the inside
of the hinged cover.
6
Alpha CD50
Alpha CD50
7
Alpha Therm Limited.
Nepicar House, London Road, Wrotham Heath,
Sevenoaks, Kent TN15 7RS
Tel: 0870 3001964
These instructions have been carefully prepared but we reserve the right to
alter the specification at any time in the interest of product improvement.
© Alpha Therm Limited 2008.
email: info@alphatherm.co.uk
website:www.alpha-innovation.co.uk
Manual compiled and designed by Publications 2000 - Tel: (01670) 356211 11/08/D229
Part No. 1.023532
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