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11 - ELECTRIC HEATER
11.1 - Electric resistance heater type - size 1.6
• Specification: 230 V (±10%) - 1 ph - 50 Hz
• Capacity per heater: size 1.6 - 1000 W +5%/-10%)
• The heater is equipped with two safety devices:
a) An automatically controlled integrated safety thermostat
with a trigger temperature of 75°C.
When the trigger temperature is reached, a resistance hea-
ter is automatically energised and prevents automatic reset-
ting, if the system is energised, but has insufficient air
flow. Reset is achieved by suppressing the supply voltage
of the electric heater. The safety thermostat protects the
unit from overheating, generally the result of electricity
passing through the heater when there is insufficient air
flow.
b) A thermal fuse tripping at 150°C.
NOTE: The minimum discharge air flow of 64 l/s (230 m
3
/h)
is required to avoid damage to the electric heaters.
CAUTION: It is vital to disconnect the 42BJ from the gene-
ral power supply before working on the electric heater.
11.2 - Shielded electric heater with spiral fins - sizes
2.6 and 4.7
This is a shielded electric heater with spiral fins. It has two
stages, each of 800 W (+5%; -10%) wired in parallel. The
electrical resistors are connected within an IP407 galvanised
sheet steel casing which is fitted with a packing gland to admit
the power supply cable.
The heater unit is fitted with a manually reset safety thermo-
stat. This normally closed contact is triggered by a rise in tem-
perature to 112°C (+0; -16).
The safety thermostat protects the unit from overheating, gene-
rally the result of electricity passing through the heater when
there is insufficient air flow. The thermostat can be reset
without dismantling the unit. Simply remove the protective
cover from the terminal box (casing) on the heater and press
the small plastic rod located in the middle of the thermostat.
However, if the safety thermostat is triggered, it is essential to
find and rectify the cause before resetting.
11.3 - Replacing the electric heater - sizes 2.6
and 4.7
If the electric heater develops a fault, the assembly must be
removed and replaced.
CAUTION:
It is vital to disconnect the ULTRA from the main power sup-
ply before carrying out any work on the electric heater.
The heating resistors and casing form a single plug-in unit to
simplify dismantling for maintenance purposes.
a) Remove the protective cover from the terminal box by
undoing the 2 hexagon head 8 mm AF screws which hold it in
place.
b) Disconnect the power supply cable from the electric heater.
This consists of three wires ending in eyelet lugs on the neu-
tral and live conductors and a flat lug on the earth conductor.
SAFETY THERMOSTAT
RESET SWITCH
ELECTRIC HEATER