Plant mode
During normal operation, the air handling unit control strategy will control the heating coil.
The input PlantMode from the control strategy module is decoded to provide the required heating valve output signal. The table below shows the heating coil overrides depending on the Plant Mode.
Notes:
Fire overrides have the highest priority over plant mode overrides.
Plant mode |
Heating valve |
Pump |
0 = off |
closed |
off (depends on OAT) |
1 = optimum start |
auto |
controlled by valve |
2 = night cycle |
auto |
controlled by valve |
3 = night purge |
closed |
off (depends on OAT) |
4 = occupied period |
auto |
controlled by valve |
5 = extended operation |
auto |
controlled by valve |
6 = delayed switch off |
auto |
controlled by valve |
11 = duty cycling |
closed |
off (depends on OAT) |
20 = frost protection |
fixed FEZ-03 |
on |
21 = fan failure |
closed |
off (depends on OAT) |
22 = overheat protection electric heater |
auto |
controlled by valve |
23 = emergency stop |
closed |
off (depends on OAT) |
30 = fire override |
auto |
controlled by valve |