0501UCA
12/25
8.8.5
If the burner has not lit within 5 seconds, the
electronic flame relay will switch off and
lockout will occur. This will cause the signal
lamp to glow within the reset push-button on
the appliance and/or on a remote control if
fitted). After 10 seconds the reset button on
the appliance or the remote control can be
activated in order to reset and restart the
appliance.
8.8.6
Flame failure protection is by the ionisation
principle i.e. the ability of a suitable flame to
pass an electrical current between the igniter
and the earthed burner assembly. To check
the flame current is adequate, remove jumper
between terminal 17 and 18 on the automatic
burner control, connect a DC micro ammeter
between the terminals. Ionisation current
should be
≥
2µA.
Note:
The terminals carry mains voltage
when energised.
8.9
How the UCA air heater works
UCA thermoelectric burner control air heaters
operate automatically after the permanent
ignition burner has been lit.
These appliances are fitted with a thermo-
electric flame failure device. External controls
(room thermostat - time switch) operate to
provide heat on. Upon switching to on, the
main burner gas valve opens and the main
burner is lit from the permanent ignition
burner.
Models fitted with hot surface ignition systems
operate fully automatically when switched
ON
and the remote controls have been set to call
for heat.
Simultaneously to being switched
ON
an
electrical circuit is made to a thermal fan
control switch to operate a heater within the
switch.
This plus the heat of the burner causes the
switch contacts close. When hot, at
approximately 45 C, the air circulation fan
will switch on and warm air will be discharged
until the burner is switched off.
Note
:
1. The fan will run on after the burner has
switched off to cool the heat exchanger.
2. During periods of extreme cold operating
i.e. morning start up, the fan may switch
on and off for short periods due to the
rapid cooling of the thermal fan switch.
This will cease as the ambient
temperature around the air heater rises.
In the event of overheating for any reason,
thermally activated, fail safe overheat controls
operate to protect the air heater. The first
control LC1 switches off the burner and upon
cooling will automatically reset.
Note
: Two LC controls, LC1 + LC2, are fitted to
UCA 75 & 95 where 2 fans are used.
The second control, LC3, which switches at a
higher temperature will if activated switch off
the main burner and on thermoelectric models
the ignition burner, thus causing controlled lock-
out. Following this manual intervention is
necessary to restart the air heater by relighting
the ignition burner or resetting an automatic
burner control after the air heater has cooled
and the LC3 control has automatically reset or
on automatic ignition models can be itself reset,
this may take a few minutes dependent upon
the ambient temperature.
8.10
Upon completion of the commissioning, ensure
the user or a responsible person is aware of;
a. How to operate air heater;
b. The need for maintenance and servicing;
Important
Ensure that these instructions and the
user's instructions are made available for
the user and/or left in a safe place, i.e.
attached to the gas service meter.
