Potterton Performa 28i Installation And Servicing Instructions page 8

Domestic Hot Water Mode
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25
24
28
20 22
21
18
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Fig. 3A
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Key
1 Primary Heat Exchanger
2 Burner
3 Ignition Electrode
4 Flame Sensing Electrode
5 Gas Valve
6 Pump
7 Automatic Air Vent
8 Plate Heat Exchanger
9 Flow Sensor with Filter
10 Pressure Relief Valve
11 Boiler Drain Point
12 Heating Return
13 Cold Water Inlet On/Off Valve and Filter
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1
2
3 4
5 6
19
8
19
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9
10
15 14 13
14 Gas Inlet
15 Domestic Hot Water Outlet
16 Heating Flow
17 Pressure Gauge
18 Hydraulic Pressure Sensor Microswitch
19 Automatic By-Pass
20 Hydraulic Pressure Sensor
21 Diverter Valve Assembly
22 Domestic Hot Water Flow Priority Assembly
23 Domestic Hot Water Flow Priority Microswitch
24 Safety Thermostat
25 Central Heating Temperature Sensor
26 Expansion Vessel & Pre-Heat Store
27 Domestic Hot Water Temperature Sensor
3.0 Appliance Operation
3.3
1. Priority is given to the domestic hot water
supply. A demand at a tap or shower will override
any central heating requirement.
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2. The flow of water will operate the DHW flow
switch which requests the 3 way valve to change
position. This will allow the pump to circulate the
primary water through the DHW plate heat
exchanger and take the stored water to give
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instant hot water.
3. The burner will light automatically and the
temperature of the domestic hot water is
controlled by the temperature sensor.
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4. When the domestic hot water demand ceases
the burner will extinguish and the diverter valve
will remain in the domestic hot water mode,
unless there is a demand for central heating.
5. If there is no other demand the pre-heat
function will operate if switched on (see Section
3.2)
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IMPORTANT: When the selector switch is in
the '0' (Off) position the electrical supply to the
boiler is isolated. The boiler will not operate
and the integral timer (if fitted) will require
resetting once the selector switch is set to
either Position (i) or Position (ii).
3.4
1. The frost protection mode is integral to the
appliance and functions only with the selector
switch (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.
3.5
1. With the selector switch (see Section 2.1) in
either the central heating or central heating and
domestic hot water position the pump will
automatically operate for 1 minute in every 24
hours to prevent sticking.
Domestic Hot Water Mode (Fig. 3A)
Frost Protection Mode
Pump Protection