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NVS Range Users, Installation & Servicing Instructions Doc Ref M102 issue 2.4 May 2018.
WARNING: Always switch off and disconnect
electricity supply and close the gas service
valve before carrying out any servicing
work or replacement of failed components.
NOTE: If a suspended air heater is to be serviced
do not lean ladders against the heater.
Ensure that an access tower or equivalent is
used.
NOTE: The access door to the controls section
may be removed to improve access.
Open the door to 90°, remove the earth cable
at the bottom, and then lift the door vertically
upwards to disengage the hinge plates.
Refit in reverse order. Ensure that the earth cable is
refitted.
2.7.1. General
Full maintenance should be undertaken not less than once
per year by a qualified person. After any servicing work
has been complete, or any component replaced, the air
heater(s) must be fully commissioned.
2.7.2. Main Burner Assembly Removal
1. Ensure that the gas service valve is turned OFF and then
unscrew the union nut situated immediately downstream
of it.
2. Disconnect the spark and rectification leads from the
control box and remove the electrical plug connections
from the top of the gas control valve assembly.
2. Disconnect the spark and rectification leads from the
electrodes and remove the electrical plug connections
from the top of the gas control valve assembly.
3. If required remove the manifold by removing the four
screws securing it to the burner assembly.
4. Remove the two screws that secure the top of the burner
assembly to the bulkhead and lift out burner assembly.
5. Using a stiff brush, not a wire brush, brush the burners
to dislodge accumulated deposits. Inspect the burners
both internally and externally to ensure that they are clean.
Examine the injectors and if damaged or deteriorated,
replace with new ones of the correct size and marking. If
deemed necessary, clean the injectors. Do not broach out
with wire.
6. Reassemble the injectors, manifold and burners in
reverse order to that above.
2.7.3. Ignition and Rectification Electrodes
Note: The ignition electrode is located at the
bottom of the burner assembly, the rectification
electrode is located at the top of the burner
assembly.
Inspect the electrodes, making sure that they are in a
sound and clean condition. In particular check that the
ignition electrode is clean and undamaged. Check that the
spark gap is 2.5mm and that the rectification probe is 10 -
12mm forward of the burner.
2.5mm
Ignition Electrode Spark Gap
2.6.7. Limit Thermostat
Thermostat settings:-
Limit
NVS 15-140SF
90°C
2.6.8. Handing over the Air Heater
Hand these instructions to the user or purchaser for
retention and instruct in the efficient and safe operation of
the air heater and associated controls. Adjust the automatic
controls to those values required by the User.
Finally, advise the user or purchaser that, for continued
efficient and safe operation of the air heater, it is important
that servicing is carried out annually.
In the event that the premises are not yet occupied turn
off the gas and electricity supplies and leave instructional
literature adjacent to gas meter.
2.7 Servicing
