What are the legal requirements for a utility room with an air-water heat pump?

In my opinion, the following sentence has always been included in the general requirements:

Hausanschlussräume müssen eine Lüftungsmöglichkeit ins Freie haben, außer Räumen, in denen nur Elektrizitäts- und Fernmeldeanschlüsse vorhanden sind.

ahh, I found something else under 5.1: Quote:

"Connection and operating equipment must be protected against mechanical damage, manipulation, and unauthorized access; they must be installed in dry and, for example, to avoid condensation, ventilatable rooms."

where "ventilatable" is not necessarily defined. An open door is also "ventilatable."

Since we have a gas boiler, the following also applies: (TE has an air-water heat pump, so it does not apply to him):

"If fireplaces are present in the room, the requirements for ventilation and combustion air supply of the installation room according to DVGW G 600 as well as the Fire Ordinance (FeuV) of the respective federal state must be observed."

so I have to keep looking there. However, I suspect that a condensing boiler with its room-air-independent burner and its own supply air in the annular gap - flue gas pipe does not need to meet any further requirements.

is also covered under 1

For single-family and two-family houses, no separate house connection rooms are required; however, the provisions regarding the connections of the lines are to be applied accordingly.

DVGW G 600 is better not to start reading at all. It contains such great things like ventilation systems and gas boilers in one room require special fire protection for the ventilation system and whatnot. So it seems to me: If a ventilation option is available, everything is fine; if not, it's not the end of the world either.