ECH 200 BD
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Pa H29: Heating mode set point
Pa H30: Mode selection differential
Ext temp: outdoor temperature
Mode may be changed from the keyboard for temperatures which fall within the mode selection differential (determined
by parameter H30).
If this is not done:
• If the outdoor temperature is less than H29, the instrument will operate in heating mode,
• If the outdoor temperature is more than Pa H29 + Pa H30, the instrument will operate in cooling mode.
8.2 Setting set points
Loads are turned on and off dynamically on the basis of temperature control functions, temperature/pressure values
detected by probes, and set points.
There are two set point values:
• Cooling set point: this is the referenced set point when the device is in cooling mode
• Heating set point: this is the referenced set point when the device is in heating mode
Set points may be modified using the keyboard, by accessing the “SET” sub-menu (refer to menu structure).
They may be given values within a range determined by parameters Pa H02 – Pa H01 (Heating) and Pa H04 – Pa H03
(Cooling).
8.3 Dynamic set point
The regulation algorithm may be used to modify the set point automatically on the basis of outdoor conditions.
This modification is achieved by adding a positive or negative offset value to the set point, depending on:
• 4-20 mA analogue input (proportionate to a signal set by the user)
or
• temperature of outdoor probe
This function has two purposes: to save energy, or to operate the machine under particularly harsh outdoor temperature
conditions.
The dynamic set point is active if:
• Activation parameter Pa H31 = 1
• probe AI3 (analogue inputs) is configured as a current input for a dynamic set point (Pa H07 = 3) or probe AI4
(analogue inputs) is configured as an outdoor temperature probe (Pa H08 = 3)
Dynamic set point control parameters:
• Pa H32= Max. offset during cooling.
• Pa H33= Max. offset during heating
• Pa H34= Outdoor temperature set point during cooling
• Pa H35= Outdoor temperature set point during heating
• Pa H36= Delta of cooling temperature
• Pa H37= Delta of heating temperature
The interaction of these parameters is illustrated in the graphs below:
Control
parameters
Cooling
Heating
Mode
Ext Temp
Pa H30
Pa H29
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