ᐅ Negative pressure monitor / chimney 4 Pa?

Which pressure switch do you recommend? Any experiences? We want to operate a fireplace (room air-independent) that requires a pressure switch. We will have decentralized ventilation from Inwert.

The chimney sweep said the fireplace must be tested at 4 Pa (0.016 inch water column) and the pressure switch must activate at 4 Pa (0.016 inch water column).

Wouldn’t the ventilation system keep shutting off constantly then?

We have a Wodtke DS01 (differential pressure monitor) and also a certified chimney. You can look up the Wodtke online.
The advantage of the Wodtke is that it is equipped with a temperature sensor. So it only measures to shut off the mechanical ventilation system — that is, ONLY when a certain temperature is reached in the stove pipe.
In the last two years, I believe the ventilation was shut off only once. It was very windy outside, and when the stove door was opened, it created a "matching" pressure situation.

Isn’t it inconvenient to connect the pressure monitor to each ventilation unit?

Doesn't the guardian switch off all decentralized devices at the same time? (I don't know how these are connected to each other)

That has to be done. However, appropriate connection cables must be installed in the house, or all fans must be connected together, for example, in the electrical panel where the pressure switch intervenes.
You need to discuss this with your electrician.

oh no... that’s going to be expensive... right?

No idea, we have a central mechanical ventilation system with heat recovery and had a cable installed directly from the chimney to the control unit of the ventilation system in the utility room.
Including everything, the pressure monitor cost us a bit over 1,000.