Which pressure switch should be provided for shutting down the controlled residential ventilation?

He does not measure pressure in the exhaust pipe, but the installation room and outside air.

Just take the P4, that is more than enough.

What then are these sensors, which are attached to the exhaust pipe, for?

So that the pressure switch is only activated when the fireplace is burning - but I don't see it as particularly sensible to invest even more money.

A ventilation system can be operated in various ways in conjunction with a fireplace. One way is, for example, to attach a temperature sensor to the chimney or flue pipe. When heating with a fireplace, this switches off the ventilation system as long as the temperature has not dropped again. This way, you can do without a pressure switch. This option is more suitable for people who rarely light the fireplace.

A ventilation system can be operated in connection with a fireplace in various ways. One way is, for example, to attach a temperature sensor to the chimney or exhaust pipe. When heating with the fireplace, it switches off the ventilation system as long as the temperature has not dropped again. This way, you can do without a pressure switch. This option is more suitable for people who rarely use the fireplace.

Basically correct, but this variant seems to me like an emergency solution. From my point of view, it definitely makes sense to distribute the fireplace heat throughout the house via the ventilation system.

It's amazing how different everything can be.

I spoke with 4 stove builders/dealers, who all told me slightly different things. So I contacted the chimney sweep.

For our new build with controlled residential ventilation, he says: I'm only interested in the stove's power in relation to the cross-section of the flue pipe in the chimney flue. The stove builder must certify the correct construction of the stove, the ventilation builder that the system exhausts as much as it supplies, then they neither need a pressure monitor, nor an air-independent stove, nor a Dibt approval.

The stove builder says: air independence is obsolete after 4 or 5 years anyway, when the seals are worn accordingly. And that you could never connect an external combustion air supply 100% airtight to the living space.

We just don't yet know how to deal with these "freedoms" from the chimney sweep.