VOKERA Mynute EHE Installation & Servicing Instructions Manual - page 23
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NOTE
You must ensure the drain valve is in the open position whilst
re-charging takes place. Replace the dust cap and carry out
the relevant commissioning procedure (section 5).
7.6
EXTERNAL FAULTS
Before carrying out any faultfinding or component replace-
ment, ensure the fault is not attributable to any aspect of the
installation.
7.6.1
INSTALLATION FAULTS
7.7
ELECTRICAL CHECKS
Any electrical checks must be carried out by a suitably
qualified person.
7.7.1
EARTH CONTINUITY TEST
Isolate the appliance from the electrical supply and, using
a suitable multi-meter, carry out a resistance test. Connect
test leads between an appliance earth point and the earth
wire of the appliance supply cable. The resistance should
be less than 1 OHM. If the resistance is greater than 1 OHM
check all earth wires and connectors for continuity and
integrity.
7.7.2
SHORT CIRCUIT CHECK
Isolate the appliance from the electrical supply and, using
a suitable multi-meter, carry out a short circuit test between
the Live & Neutral connections at the appliance terminal
strip (fig.14).
Repeat above test on the Live & Earth connections at the
appliance terminal strip (fig.14).
NOTE
Should it be found that the fuse has failed but no fault is
indicated, a detailed continuity. Check will be required to
trace the fault. A visual inspection of components may also
assist in locating the fault.
7.7.3
POLARITY CHECK
With the appliance connected to the electrical supply and,
using a suitable multimeter, carry out the following voltage
tests:
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connect test leads between the Live & Neutral connec-
tions at the appliance terminal strip (fig.14). The meter
should read approximately 230V ac. If so proceed to next
stage. If not, see 7.7.4.
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connect test leads between the Live & Earth connections
at the appliance terminal strip (fig.14). The meter should
read approximately 230V ac. If so proceed to next stage.
If not, see 7.7.4.
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connect test leads between the Neutral & Earth connec-
tions at the appliance terminal strip (fig.14). The meter
should read approximately 0 - 15Vac. If so polarity is
correct. If not, see 7.7.4.
7.7.4
REVERSED POLARITY OR SUPPLY FAULT
Repeat the above tests at the appliance isolator, if testing
reveals correct polarity and/or supply at the isolator, re-
check wiring and connections between the isolator and the
appliance.
If tests on the isolator also reveal reversed polarity or a
supply fault, consult the local electricity supplier for advice.
7.7.5
RESISTANCE TO EARTH CHECK
Isolate the appliance from the electrical supply and, using
a suitable multi-meter, carry out a resistance test. Connect
test leads between the Live & Earth connections at the
appliance terminal strip (fig.14). If the meter reads other
than infinity there is a fault that must be isolated, carry out
a detailed continuity check to identify the location of the
fault.
IMPORTANT
These series of checks must be carried out before attempt-
ing any faultfinding procedures on the appliance. On
completion of any task that required the disconnection and
re-connection of any electrical wiring or component, these
checks must be repeated.
7.8
FAULT FINDING
Before attempting any faultfinding, the electrical checks as
detailed in 7.7 must be carried out. Isolate the appliance
from the electrical supply. Disconnect any external controls
such as room thermostats etc. from the boiler.
7.8.1
REPLACING THE MAIN PCB
When replacing the main PCB it’s essential that the
potentiometers are set as follows:
●
P4
- set at minimum
●
P5
- set at maximum.
EFFECT OF JUMPER TAGS FITTED TO THE MAIN PCB
AT:
●
JP1
- required for Mynute EHE System boiler
●
JP2
- cancels anti-cycle function and initial heating
output (75% of maximum at start up)
●
JP3
- required for LPG boilers
●
JP4
- unused.
Restore the electrical supply to the boiler and turn the
selector switch to the ‘ON’ position. The boiler should now
function as described in section 7.2. Should the boiler fail
to respond, the internal fuses and connectors should be
checked to ensure integrity and continuity. If the boiler still
fails to respond, refer to the detailed faultfinding flowcharts
overleaf.
7.9
FAULT CODES
When the boiler is in a fault condition, the LED is displayed
in a colour and/or frequency that is relevant to the fault. To
reset the boiler, turn the mode selector switch to the
RESET
position (
) for 2-minutes’ then back to the relevant mode
of operation.
If the boiler does not reset, refer to the following section and
the detailed faultfinding flowcharts overleaf.
Symptom
Possible causes
No ignition
Check wiring
Check electrical supply
No hot water
Check external controls
No central heating
Check wiring of room thermostat
and/or other external controls
Frequency
Faults/Status
On every 6-secs
At stand-by with no faults
Flashing 8-times a second
SARA function active
On every 0.5-secs
desired temperature satisfied
On every 0.5-secs
Temporary fault, e.g.:
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APS fault
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low water pressure
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condense pressure switch
Solid
Active for heat request
GREEN LED
Frequency
Faults/Status
On every 0.5-secs
CO function active
Solid
Internal fault (see 7.2.4.1)
YELLOW LED
Frequency
Faults/Status
Solid
Final fault, e.g.:
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water pressure switch
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condense pressure switch
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fan/flue problem
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primary NTC open/short circuit
On every 0.5-secs
limit thermostat
RED LED