Ideal Icos Sequence of operation
Boiler Operation (from cold)
Initial Power Up
When the main supply (230 Vac) is applied to (L3) the display will show 3. Approximately 3 seconds later the display will show 0, indicating standby mode. When the system controls are turned on (L1 to L2) the display will show c with a green flashing LED. The fan will run at ignition speed (3500 rpm) which is approximately 90% maximum CH rate. After 5 seconds the ignition will commence and 1 second later the gas valve will operate. The PCB will expect detection (ionisation) within 4 seconds. The spark will continue for the full 4 second ignition period. The green LED will be solid when detection is confirmed.
The fan will then increase to maximum speed (4140 rpm).
Note: If the PCB does not detect an ionisation current within 3 seconds the boiler will reattempt ignition. There will be a total of 3 ignition attempts and the fan will run for a post purge period of 30 seconds between each ignition attempt. If ignition is not detected, the boiler will lockout (see sheet).
The boiler will continue to fire at maximum rate until the flow temperature reaches 3 ° C below the set point. The boiler will then modulate down to suit the heating load. If the temperature rises 2 ° C above the set point the boiler will switch off. The boiler will re-ignite at 5 ° C below the modulating temperature.
Example - Boiler set point 82 ° C, boiler modulates at 79 ° C, boiler off at 84 ° C and boiler on at 74 ° C.
When the boiler switches off on temperature and the system controls are still “calling”, the green LED will flash until ignition is re-established.
Icos system
All of the above characteristics are applicable to icos system, with the inclusion of the following:
When the system controls are switched off, the pump will over-run for approximately 5 minutes and the display will show c.
