Purge Valve

Overview

DCT version 1.69.279 and Brain version 3557 add an option to specify a purge valve on the "Output to Valve Selection" setup page. This valve is used in parallel with the suction block valve to start and load the unit, with the purge valve on during startup and the suction block valve on later.

Logic

If no purge valve is assigned the suction block valve will be off when the unit is not running and will come on during startup. If a purge valve is assigned, the suction block valve logic will change:

• During unit off: Both valves are closed
• During purge, startup, and warmup: only purge is open
• After suction open trigger (see below): Suction block opens then purge closes after a delay

The purge valve setup (under Brain output setup) is used to specify the condition where the suction valve will open after the unit is running.

After the unit is running (and B timers counting down) the Brain will check for the condition on line one of the above page. Once the condition is met for 2 seconds, the main suction block valve will open. After opening, the purge valve will close after the specified delay.