3.0 Appliance Operation
6
3.1
Operating Mode (Fig. 2)
1. With a demand for heating, the pump circulates
water through the primary circuit. At a pre-
determined flow rate the hydraulic differential
pressure switch operates, initiating the ignition
sequence.
2. The main burner ignites at low rate, then the
gas valve controls the gas rate to maintain the
heating temperature measured by the
temperature sensor.
3. When the flow temperature exceeds the setting
temperature, a 3 minute delay occurs before the
burner relights automatically (anti-cycling). The
pump continues to run during this period.
4. When the demand is satisfied the burner is
extinguished and the pump continues to run for a
period of 3 minutes (Pump Overrun).
IMPORTANT:
When the selector switch is in
the ‘0’ (Off) position the electrical supply to the
boiler is isolated. The boiler will not operate.
3.3
Frost Protection Mode
1. The frost protection mode is integral to the
appliance and functions only with the selector
switch (see Section 2.1) in the domestic hot water
and central heating position. If the system
temperature falls below 5° C then the boiler will
fire on its minimum setting until a flow temperature
of 30° C is reached. Further protection can be
incorporated by using a system frost thermostat.
3.4
Pump Protection
1. With the selector switch (see Section 2.1) in
either the central heating or central heating and
hot water position the pump will automatically
operate for 1 minute in every 24 hours to prevent
sticking.
1
2
4
5
6
7
8
19
18
9
10
12
11
14
13
15
16
17
3
Key
1
Heat Exchanger
2
Burner
3
Ignition Electrode
4
Flame Sensing Electrode
5
Gas Valve
6
Pump
7
Automatic Air Vent
8
Pressure Relief Valve
9
Boiler Drain Point
10
Gas Inlet
11
Boiler Flow
12
Boiler Return
13
Pressure Gauge
14
Automatic By-Pass
15
Hydraulic Differential Pressure Sensor
16
Safety Thermostat
17
Central Heating Temperature Sensor
18
Expansion Vessel
19
Water Heating Sensor
Boiler Primary Circuit
Fig. 2
Summary of Contents for Performa System 12e
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