Cooling Pre-Control in a 4-Pipe System

In a 4-pipe system are two independent pre-control circuits, one for heating and one for cooling. In this case, we can provide heating and cooling energy at the same time, when the “HVAC_Mode” input takes the value “auto”.

We need both pre-control macros, this macro and the heating pre-control macro “PRCH_PreCtrlHtg“

For a correct  4-pipe cooling operation, do the following:


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

Table 1.   Pre-control cooling operation

HVAC_Mode

SYS-01

Pre-control Cooling

0,1

1

off

2

1

off

3

1

cool

4

1

cool