17. Operational Flow Diagrams
1. Central Heating Mode
End of a domestic | Escape pause by |
hot water overrun | resetting the mains |
| electricity supply |
| |
Operating Switch |
|
(or programmer) |
|
and room |
|
thermostat on |
|
Main gas valve | ||
OFF | ||
|
Central heating | Operating Switch |
temperature 5¡C | (or programmer) |
above set point | OFF |
| EITHER |
6 |
|
Room thermostat
OFF
Gas valve OFF
CENTRAL HEATING | Water flow | |
temperature | ||
DEMAND | ||
monitored by central | ||
| heating sensor | |
Internal | Pump on | |
"Autofrostat" | ||
| ||
demand |
|
24
AUTOMATIC START-UP SEQUENCE
YES
Is fan in | NO | Air pressure PASS |
overrun mode? |
| switch test |
|
| FAIL |
AUTOMATIC | Burner pressure | |
1.0 mbar for 60 | ||
seconds. | ||
SEQUENCE | ||
|
Initiate
sparking
Fan ON | Sense air | Main valve | |
pressure | opens | ||
|
PRESENT
ABSENT
Burner pressure
automatically
adjusted for range
rating and then
modulated to
maintain set flow
temperature
Stop
sparking
Sense flame
ABSENT
CENTRAL
HEATING
DEMAND
SATISFIED
PRESENT
Continue
pump overrun for 6 secs pump pulse after
2 miniutes.
Fan overrun
4 minutes
Wait (pump on |
in central |
heating mode) |
Wait
(fan or fan and
pump on)
Ignition Time - | Ignition |
out (after 9secs) |
Wait
(fan or fan and
pump on)