Page 19
UNIT HEATER
2.6.2 Sequence of Events
With the external controls on and calling for heat, the control box will self check and then begin a start
sequence.
Electric Ignition ON
Start Gas Valve Energises
The start gas valve opens and once a flame has been established this remains on until close down. The
flame probe is now continuously monitoring for the safe presence of flame.
Electric Ignition Off
Five seconds later the electric ignition turns off, leaving the start gas flame to be proved as stable.
Main Gas Valve Energises
Following a short delay the main gas valves energise and the main flame cross lights from the start gas.
The control is now in its normal run position.
Close Down
When the external controls are satisfied the control box turns off all outputs simultaneously and returns
to rest position for the beginning of the next sequence.
2.6.3 Fault Conditions
If at any stage the flame fails the control will go to ‘lockout'. The red light will glow and the control
will need to be manually reset before any further start attempt can be made.
Minimum flame probe current 1 µA DC.
Typical flame probe current 3-5 µA DC
2.7 External Controls
CUH... range heaters may be operated from external controls or consoles supplied by Combat
Engineering Ltd. which are described in their own instructions book.
The wiring diagrams for the external controls are shown in Section 5.
To Next Page
Loading...
