Frost protection thermostat

To protect the heating coil against freezing a frost alarm procedure starts as soon as the frost protection thermostat detects a frost alarm. If the frost alarm condition is returned to the normal position a frost recovery procedure starts.

Frost alarm procedure:
If a frost alarm occurs, the heating coil will:


Frost recovery procedure:
When the frost alarm condition returns to normal, the following happens:


See the ramp function to normal control in the next figure.


 

If no return water senor is connected, the valve position, defined by parameter FEZ-03, returns to its normal control position via a ramp-down function defined by parameter FEZ-04 whenever the:

The heating coil starts whenever the plant mode changes from any un-occupied mode to any occupied mode.

Description

Default value

FEZ-01: frost protection RWT/ DAT setpoint raise

15 K

FEZ-02: raised setpoint decrease during frost recovery

1 K/min

FEZ-03: valve position during frost protection

100 %

FEZ-04: valve raised position decrease during frost recovery

10 %/min