Section 1: introduction
Page 6
1.5 Boiler Components
1.5.1 Burner
The Grant External Vecta boiler uses a drop feed type burner with
modulated heat output. The burner output is determined by varying
the feed and pause time of the pellet feed auger supplying pellets to
the burner. Refer to Section 9 for details of burner operation.
The burner is supplied factory-fitted in the boiler and is equipped with
a self-cleaning device to prevent a build-up of ash and clinker in the
burner brazier.
The boiler is supplied with the control parameters factory set to
default settings.
During commissioning these control parameters should be checked
to ensure they are correct. Refer to Section 11.5 for details.
1.5.2 Heat exchangers
The Grant External Vecta 4-16 condensing boiler is supplied with
a combined primary and secondary heat exchanger. Both heat
exchangers are equipped with a self-cleaning system.
1.5.3 Boiler controls
after the burner has been switched off (either manually by the
On/StanDBY switch on the control panel, or automatically by
the boiler control system, or the heating system controls) the
burner needs to burn-down the remaining pellets in the brazier.
Do not open the front combustion chamber access door until
the burner display reads ‘Standby’.
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The Setpoint temperature of the boiler is user adjustable via the boiler
control panel - refer to Section 9.4 for details.
The boiler control panel is located at the upper left corner of the boiler
(behind the hinged front door of the boiler). Refer to Figure 1-5. To
unlock/open the front door of the boiler, first unlock and remove the
padlock (if fitted). Rotate the knob of the catch clockwise to unlatch
and open the front door.
This control panel includes the following items (refer to Section 9.4 for
further details of the control panel functions):
•
‘ON/STANDBY’ switch – to switch the burner off when required,
by interrupting the switched live supply to the burner. This switch
does not isolate the electrical supply to the burner.
•
LCD screen – to display the boiler operating condition and (when
necessary) a fault code
•
Boiler control setting buttons – Refer to Section 9 for boiler
control system operation and setting.
Figure 1-5:
Boiler control panel
The boiler also includes an overheat thermostat – located at the
bottom left corner of the boiler (inside the front door) with the reset
button under the removable plastic cap. Refer to Figure 11-3. The
overheat thermostat bulb is situated in the top front left corner of the
boiler, along with the boiler control thermistor sensor. Refer to Section
11.3 for the location of the bulb and sensor.
This overheat thermostat allows the boilers to be used on a sealed
central heating system and will automatically switch off the boiler if the
pre-set temperature of 100°C is exceeded.
1.5.4 Boiler Pellet Hopper
The Grant External Vecta boiler has an integral pellet hopper with a
capacity of 80kg. This is accessed by lifting the hinged hopper lid on
the top of the boiler so that pellets can be tipped into the hopper by
the user.
The hopper is fitted with a contents switch. This detects when the
level of pellets in the hopper falls to a pre-set minimum value. At this
point the LCD screen will flash and display the ‘Fuel Low Warning’
message. The Grant logo indicator will also flash slowly to indicate the
pellet level has fallen to the pre-set minimum. Refer to Section 1.5.
As soon as this happens the hopper should be topped up with more
pellets. This will automatically cancel the flashing Grant logo and
the flashing ‘Fuel Low Warning’ message on the control panel LCD
screen.
If the pellet hopper is not topped up at this point, the boiler
will continue to operate for a short period before the burner is
automatically stopped. The Grant logo will continue to flash slowly,
with the flashing ‘Low Fuel Warning’ message on the control panel
LCD screen, to indicate the lack of pellets in the boiler.
If this happens, simply top up the hopper with more pellets. A
minimum of 20kg of pellets will operate the contents switch and
automatically re-start the burner (as long as there is a demand for the
boiler to run).
To top up the hopper, first set the ‘ON/STANDBY’ switch to ‘STANDBY’
and wait for the boiler to stop. Then open the hinged hopper lid (on
the top of the boiler) and tip in the required amount of pellets. Then
close the hopper lid and reset the ‘ON/STANDBY’ switch to ‘ON’.
Whilst topping up with pellets, ensure that no foreign debris enters the
hopper.
the hinged hopper lid is fitted with a safety cut-out switch and
MUSt BE CLOSED for the boiler to operate. if the lid is opened
for longer than 5 seconds, whilst the boiler is operating, the
burner will be automatically stopped. Closing the hopper
lid resets the cut-out switch and the boiler will restart. Refer
to Section 11.4 for details of the hopper lid cut-out switch
operation.
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1.5.5 Frost Protection
The Grant External Vecta wood pellet boiler is supplied with a factory-
fitted frost protection thermostat. This is pre-set to operate when the
air temperature falls to 2°C.
This frost thermostat is located inside the PCB enclosure and wired to
the boiler terminal block. For details of the frost thermostat electrical
connections, refer to Section 8.6.
