Having a zone valve open for some time, after the boiler stops would be a good idea. This helps with the dissipation of heat and the prevention of pressure building up.
CASE 1:
If boiler is triggered by zone valve, then boiler overrun is the way to prevent pressure build-up.
CASE 2:
If boiler is triggered by GPIO, then as soon as boiler stops the zone valve closes(triggered by GPIO or Zone Controller), but residual heat will not be dissipated and pressure would build.
Having a zone valve open for some time, after the boiler stops would be a good idea. This helps with the dissipation of heat and the prevention of pressure building up. CASE 1: If boiler is triggered by zone valve, then boiler overrun is the way to prevent pressure build-up. CASE 2: If boiler is triggered by GPIO, then as soon as boiler stops the zone valve closes(triggered by GPIO or Zone Controller), but residual heat will not be dissipated and pressure would build.