Freeze Protection

If the filtered outside air temperature is lower than the frost protection limit FRZ-03 (2 °C) and the frost protection is enabled (FRZ-01=1), the pre-control flow temperature cannot get lower than this minimum value defined in the parameter FRZ-02.

If the flow temperature is between the frost protection setpoint and the P-band of the flow temperature controller, the valve will be modulated between 0 and 100% and a heat demand will be sent to the heat generators.

If FRZ01 =2 additionally, then the heating pump will run in a cyclic mode switching on and off.

Table 6.   Pre-Control Parameter List

Description

Value Range

Default Value

Unit

FRZ-01: enable freeze protection

0 = no frost protection

1 = limited to FRZ-02

2 = enabled with cyclic on/off

0 ... 2

1

-

FRZ-02: flow temp. setpoint frost protection

2 ... 20

10

°C

FRZ-03: OAT limit frost protection

-50 ... 50

2

°C

FRZ-04: frost protection heating pump runtime for cyclic on

0 ...720

60

sec

FRZ-05: frost protection heating pump delay for cyclic off

0 ...180

5

min