iPonic 624® Manual PN 995-1124-00
18| Page
When the temperature in the grow room rises above the
Cool Setpoint
, the system
enters the first stage of cooling (referred to as
Cool 1
). If the temperature
continues to rise, the system will enter the second stage (
Cool 2
), then the third
stage (
Cool 3
) and so forth. The goal is to drive the temperature to the normal
temperature range.
The same occurs when the temperature drops below the
Heat Setpoint
. The only
difference is that there is a maximum of two heating stages.
Deadbands
If the room temperature rises above the
Cool Setpoint
, the cooling equipment will
be activated to bring the temperature back to the normal temperature range.
Without a deadband, this can cause the system to “short cycle” – that is, oscillate
rapidly between the cooling stage and the normal stage. To limit the oscillations, a
temperature band (deadband), often 1-2 degrees, is set below the temperature cool
setpoint. As the temperature rises in the room and exceeds the cool setpoint, the
first stage of cooling is engaged. When the room temperature drops below the cool
setpoint, it remains in its first stage of cooling until the temperature drops below
the cool setpoint – the deadband. Then it goes into the Normal stage. The
narrower the deadband, the more the equipment goes on and off, but the tighter
the temperature control.
The same process occurs with the
Heat Setpoint
. In this case, as the room
temperature falls below the heat setpoint, the heating equipment is engaged.
When the heat rises above the heat setpoint, it stays on until the temperature
exceeds the heat se the deadband.
The temperature staging, deadbands and ramping are illustrated in the figure
below.
Deadbands are also used with humidity control, CO
2
control and light control.
Ramping
Ramping
lets you control how gradually or rapidly you want to change the temperature
and humidity targets between setpoint periods. If the night temperature targets are less
than the day targets, for example, you may want to gradually adjust the setpoints so as
not to shock the plants. Besides being good for the plants, it can also save on energy.
However, there are cases, depending on the crop, where sharp ramping, or a quick
increase or decrease of the plant temperature is desirable. This is sometimes referred to
as DIF.
By default, the Ramp time is set to 0 and in this case, there will be an immediate step
transition in the setpoints. If you enter a Ramp time, it will always occur at the
beginning of the Set Point time period. Example of temperature ramping is illustrated
below:
