Final Assembly; User Information; Boiler Operation; Central Heating Mode - Dunkirk DCC-150 COMBI Manuel D'installation, D'utilisation Et D'entretien

15.3 FINAL ASSEMBLY

• Place the front casing in position over the boiler ensuring the bottom is located behind the control panel and secure in position
at the top using the screws previously removed.
• If the boiler is to be left in service with the User, set the controls and room thermostat (if fitted).
• If the boiler is not to be handed over immediately, close the boiler gas service cock and switch off the electrical supply.
• If there is any possibility of the boiler being left during frost conditions, then the boiler and system should be drained. (see
section 18: "COMPONENT REPLACEMENT OR PERIODIC CLEANING"). It is recommended that a label is attached to the
boiler drawing attention to the fact that the system has been drained.
• Complete the details of the installation on the back page of this manual.

15.4 USER INFORMATION

The User must be advised, and demonstrated if necessary, of the following important points:
• How to light and turn off the boiler and how to operate the system controls.
• The importance of annual servicing of the boiler to ensure safe and efficient operation.
• That any servicing or replacement of parts must only be carried out by qualified personnel.
• Ensure that the boiler controls and room thermostat, if fitted, are set to the User's requirements.
• Tell the User about the sealed system pressure.
• Tell the User that if the display is active and the boiler has not operated for 24 hours for heating or hot water, the pump will
automatically operate for 5 minutes.
• Explain to the User that an internal frost thermostat is fitted in the boiler, and that electrical supply to the boiler must be left on
for the thermostat to operate.
• Show the User the position of the pressure relief valve discharge pipe.
• Hand the User's instructions to the User.
• Leave these Installation and Servicing instructions with the User for use on future calls.

16. BOILER OPERATION

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 the hot water mode until the demand is satisfied i.e. storage water is to the required
temperature. This interruption in the central heating is only when the demand for hot water is present and should not be noticed
by the User.

16.1 CENTRAL HEATING MODE

If there is a call for heat, the pump will start to circulate the central heating water, operating the flow switch. The fan will run; once
the fan speed is reached the burner will light. The burner output then automatically adjusts to suit the system demand; as the
temperature of the water in the boiler approaches that set by the adjustable temperature selector, the burner output is reduced.
When the set temperature is reached, the burner is turned off and the fan stops. The pump continues to run for three minutes to
remove residual heat build up in the boiler. The burner will not relight for 3 minutes. If the CH sensor has not registered the pre-set
temperature but the room thermostat is satisfied the burner is turned off, the fan stops and the pump continues to run for three
minutes. In this instance there is no 3 minute delay before the burner will relight. If there is a demand for DHW during the 3 minute
burner delay, the boiler will operate to provide DHW until the tap is closed; the boiler will then immediately revert to provide CH if
there is a demand.

16.2 DOMESTIC HOT WATER MODE

When a demand for hot water (by opening a hot tap, etc.) is sensed by the flow switch, the pump starts and the burner lights at
its ignition output, increasing to its maximum output. Water in the boiler is then diverted from the central heating system to the
domestic hot water heat exchanger, heating the incoming supply water. The burner output is varied to maintain the temperature
of the hot water as that set by the adjustable temperature selector. When the flow switch senses that the hot water is no longer
required the burner is turned off and the boiler immediately returns to the central heating mode.

16.3 FROST PROTECTION

The boiler incorporates a built in frost thermostat which automatically turns on the boiler and pump if the water in the boiler falls
below 41°F / 5°C, providing the display is switched on the boiler will operate until the water temperature in the system reaches
approximately 86°F / 30°C. Frost protection is for the boiler only and not for the complete Central Heating System.

16.4 PUMP

If the display is switched on and the boiler has not operated for 24 hours for heating or hot water, the pump will operate automatically
for five minutes every 24 hours.

16.5 LWCO - LOW WATER CUT OFF

This device protects the primary exchanger from damage by not allowing the boiler to run in a LOW water pressure situation. The
low water condition occurs when the water pressure drops below 7.0 psi (0.5 bar), approximately.
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240011373, Rev. G [03/31/2017]