VOKERA Linea Installation & Servicing Instructions Manual - page 6
Supplied By www.heating spares.co Tel. 0161 620 6677
Linea Max
2
SECTION 2
DESIGN PRINCIPLES AND OPERATING SEQUENCE
2.1
Fig.1 illustrates the general layout of compo-
nents. Fig.2 illustrates the operating princi-
ples described below.
2.2
Central Heating Mode
2.2.1
When the various switches and controls
impose a demand for heat, the pump is
started. The flow of water from the pump
operates a flow switch. This in turn ener-
gises the electronic circuitry. The fan is
started, the gas valve is energised at an
intermediate rate and the electronic ignition
goes through an ignition attempt.
2.2.2
The burner ignition is checked by the elec-
tronic circuitry to ensure correct ignition of
the burner.
2.2.3
As water temperature increases this is
sensed by the temperature sensor on the
flow pipe which modulates the burner to
match the heat output to the heat require-
ment of the system.
2.2.4
Depending on the load, either a) the water
temperature will continue to rise and the
burner will continue to modulate down until
the maximum setting is reached at which
point the burner is switched off, or b) the
water temperature will fall and the burner
will return to a higher output to match the
demand.
2.3
Domestic Hot Water Mode
2.3.1
The appliances incorporate a hot water
preheat facility. The appliance will therefore
ignite periodically to maintain heat within the
appliance.
2.3.2
The appliance will operate in domestic hot
water mode whenever the mode selector
switch is on regardless of mode selector
switch position and any demand for central
heating.
2.3.3
The diverter valve will automatically ener-
gise into the hot water position after central
heating demand, or will stay in the hot water
position after hot water demand. Opening a
draw off tap will energise the pump and fan
sending primary water to the domestic hot
water heat exchanger.
2.3.4
Temperature control is transferred to the
domestic hot water thermostat
(potentiometer) which modulates the burner
output between high and low flame to
maintain an average heat input to suit the
dhw output required.
2.3.5
An overrun is incorporated in the boiler in
both c/h & dhw modes. The fan overruns
until the boiler water cools to approximately
80°C (176°F).
2.4
Safety Devices
2.4.1
In both central heating and hot water modes
safe operating is ensured by:
A.
Differential pressure unit in the primary
circuit which prevents burner operation if
water flow rates are too low.
B.
An electronic device that checks the
primary pressure unit for activation. Failure
results in deactivation of the pump, after
approximately 10 minutes of operation.
C.
A safety thermostat, which interrupts the
control circuit shutting off the gas valve. At
the same time the fan will still operate.
D.
A Pressure differential switch in the flue
system to check the fan's operation before
allowing ignition.
2.4.2
A safety valve is provided to relieve excess
pressure from the primary circuit.
2.4.3
Frost Thermostat
The appliance has a built in frost protection
circuit. Should the boiler temperature sensed
at the primary
thermistor fall below 5°C, the
boiler will operate in central heating mode and
continue to operate until the primary thermis-
tor reaches approximately 40°C.
KEY:
A
Gas
B
Hot Water Outlet
C
Cold Water Inlet
D
Central Heating Flow
E
Central Heating Return
Fig. 2
This drawing is indicative only and does
not accurately represent pipe positioning.
A
B
C
D
E
flue outlet
air intake
26
2
4
7
11
9
24
22
21
16