I’ve actuators that have a delay time for about 2,5 min. Is it possible to set an on delay time for the heater so the pomp won’t be on when none of the valves are open?
No, there is no delay time for the pump, this is also not nessesary, a pump may always running.
That’s not exactly true. When there’s no flow in the system, the pump gets broken after a period of time.
But ok, now I know that I need to have a pressior egalisation system or a valve that’s open when all the others are closed.
Most pumps (e.g. Wilo) don’t care if the water flows or not.
it isn’t the pump only, when there’s a demand of heat, the heater starts and the internal pump begins to pump (standard in a normall condens heater cannot be changed), the problem is when for over a few minutes there’s no flow and the heater heats the water in his boiler, it’s enough to let the heater goes into overtemperature. For the lifetime of the pump, it isn’t that good for the pump pumping with no flow (the pump starts to cavitate, ok for a few times but not everytime). So I think I’ll install an automatic bypass (differential pressure valve) like ie du145 of honeywell to do the trick. Than in case of all the valves closed, I’ll have a flow for the time during the opening dead time of the valves.