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8
CHECKS, ADJUSTMENTS, AND
FAULT FINDING
8.1 Checking appliance operation
When carrying out any repairs or servicing to the appliance, the rele-
vant commissioning procedure must be undertaken to ensure the con-
tinued safe operation of the appliance. Particular attention should be
made to ensure gas soundness, water soundness, and the electrical
integrity of the appliance.
8.2 Appliance mode of operation
When there is a request for hot water via a hot water outlet or tap, the
water flow switch senses water movement thereby energising the fan.
b
There must be sufficient inlet water pressure and flow (min. 0,15
bar/ 2 lpm) to ensure the water flow switch is activated. If there
is insufficient pressure and/or flow, the appliance will be prevent-
ed from operating. When the fan runs, it proves the differential
air pressure switch which in-turn allows an ignition sequence to
begin.
b
The ignition sequence lasts approximately 7 seconds, during
which the appliance will continue to spark even if the burner has
already lit. If the spark/sensing electrode does not sense ignition
the appliance will then go to lockout. Ignition is sensed by the
electronic circuitry to ensure flame stability at the burner. Once
successful ignition has been achieved, the electronic circuitry
allows the full gas rate through the appliance. When the appli-
ance reaches the desired temperature the burner will modulate
to maintain the set temperature. Should the temperature contin-
ue to rise the burner will shut off when the maximum operating
temperature is attained. When the request for heat and/or hot
water has been satisfied, the fan may continue to operate to
dissipate any residual heat within the appliance.
8.3 Checking and adjusting burner pressure
Altough the burner pressure is factory set, it is necessary to check it
during servicing or if the gas valve has been removed. Isolate the ap-
pliance from the electrical supply and attach a suitable manometer to
the gas valve outlet test nipple.
SETTING THE MAXIMUM BURNER PRESSURE
Light the appliance as described in 5.10 & 6.4 and compare the read-
ing on the manometer with the value described in 2.2 TECHNICAL
DATA. If adjustement is required, remove the protective cap from the
gas valve modulating coil assembly and turn the outer (10mm) nut
clockwise to increase, or counterclockwise to decrease the burner
pressure.
b
You should ensure that one or two hot water outlets are fully
open during the above procedure. This will ensure that the out-
put of the appliance (burner pressure) is not compromised due
to a high outlet temperature.
SETTING THE MINIMUM BURNER PRESSURE
Once the maximum burner pressure has been checked and/or adjust-
ed, remove one of the grey wires from the modulating coil. Compare
the reading on the manometer with the value described in 2.2 TECH-
NICAL DATA. If adjustement is required, turn the inner (red) cross-
head screw clockwise to increase, or counter-clockwise to decrease
the burner pressure, whilst ensuring that the outer (10mm) nut does
not move. When checking and/or adjustement has been completed,
isolate the appliance from the electrical supply, replace the protective
cap, refit the grey wire to the modulating coil, remove the manometer,
and tighten the outlet test nipple.
b
A gas soundness check must be carried out.
8.4 Maintenance
To ensure correct operation over time, the appliance should be
checked by a qualified professional at least once a year.
IMPORTANT
: before performing any cleaning or maintenance work, or
before opening or removing the boiler panels, turn the appliance off by
shutting off the gas tap.
that the flue gases passage sections of the heat exchanger are
Check
not obstructed. Use a wet soapy cloth to clean the external panels.
Do not
use abrasive solvents, powders or sponges.
clean the appliance or its component parts with highly flam-
Do not
mable substances such as : petrol, alcohol or heavy oil.
Check
electrode position and distance.
7 ±1.5
21
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