page no. 36 of 44
NVx Range Users, Installation & Servicing Instructions issue 6.4 Aug 2017.
2.6.7. Fan/Limit Thermostat
Thermostat settings:-
Fan Off Fan On
Limit
NVx 15-140SF
86°F/30°C 122°F/50°C 212°F/100°C
Note: NVx 15 to NVx 75 units have one fan/limit
thermostat whereas NVx 90SF to NVx 140SF
units have two. The second thermostat is at the
opposite end of the heater to the burner/
controls end.
The fan circuits are wired in parallel (either thermostat
will turn on the fan) and the limit thermostats are wired in
series (either thermostat will shut down the burner)
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.
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 and tested for
soundness as described in Section 2.6.
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.
2.6.6.2. Flame Current
1. To measure the flame current connect a multimeter
capable of measuring micro amps as shown in the
following diagram.
2. Minimum current reading is 0.5µA and normal value
should be 1.5µA or higher.
Flame Current Measurement
2.6.6.3. Air Heater Controls
1. Close the gas service tap and ensure that the gas valve
is heard to close within 1 second and that the lockout light
is illuminated. Note that the heater may attempt five re-
ignitions before going to lockout. Open the gas service tap
and reset the unit from lockout.
2. Check that the room thermostat and all automatic
controls are operating satisfactorily.
2.7 Servicing
