Cooling Pre-Control in a 2-Pipe System

For a 2-pipe system a common pipe system is used for heating and cooling pre-control circuits.

These systems cannot provide heating and cooling energy at the same time. When the “HVAC_Mode” input takes the value “auto”, both heating and cooling pre-control circuits will switch off.

We need both pre-control macros, this macro and the cooling pre-control macro “PRCC_PreCtrlClg“.

For a correct 2-pipe cooling operation:

With these settings, the heating pre-control will operate as shown in the next table:

Table 2.   Pre-control cooling operation

HVAC_Mode

SYS-01

Pre-control Cooling

0,1

0

off

2

0

off

3

0

cool

4

0

off