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 except minimum RWT control depending

off (depends on OAT and RWT control)

1 = optimum start

auto

controlled by valve

2 = night cycle

auto

controlled by valve

3 = night purge

closed

off

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)




30 = fire override

auto

controlled by valve