Mandatory replacement of old boilers yes or no?

As a realtor, I hear this time and again: The boiler is almost 30 years old, I have to replace it when I buy it.

What does the Building Energy Act say about this?

Here is the text of the GEG § 72:

Law for the saving of energy and the use of renewable energies for heating and cooling in buildings* (Building Energy Law - GEG).
§ 72 Prohibition of operation of boilers, oil heating systems
(1) Owners of buildings may no longer operate their boilers that are fed with a liquid or gaseous fuel and were installed or erected before January 1, 1991.

(2) Owners of buildings shall not operate their boilers that are charged with a liquid or gaseous fuel and were installed or erected on or after January 1, 1991, after the expiration of 30 years from the date of installation or erection.

(3) Paragraphs (1) and (2) shall not apply to the following

1. low-temperature boilers and condensing boilers and

2. heating systems whose rated output is less than 4 kilowatts or more than 400 kilowatts.

(4) As of January 1, 2026, boilers fired with fuel oil or solid fossil fuel may be installed in a building for the purpose of commissioning or placed in a building only if

1. a building has been erected or is being erected in such a way that the heating and cooling energy requirements pursuant to section 10(2)(3) are covered proportionately by renewable energies in accordance with sections 34 to 41 and not by measures pursuant to sections 42 to 45,

2. an existing public building has been or is being altered in accordance with section 52(1) in such a way that the heating and cooling energy requirement is covered proportionately by renewable energies in accordance with sections 52(3) and (4) and the obligation under section 52(1) has not been or is not being met by a substitute measure under section 53,

3. an existing building has been constructed or altered in such a way that the heating and cooling energy requirement is covered proportionately by renewable energies, or

4. an existing building cannot be connected to a gas supply network or to a district heating distribution network because no general supply gas network or no distribution network of a district heating supply company is adjacent to the property and a proportionate coverage of the heating and cooling energy demand by renewable energies is not technically possible or would result in undue hardship.

The obligations under section 10 (2) no. 3 and section 52 (1) shall remain unaffected.

(5) The first sentence of subsection (4) shall not apply if the decommissioning of a heating system operated with heating oil or solid fossil fuel and the installation of a new heating system not operated with heating oil or solid fossil fuel leads to undue hardship in an individual case due to special circumstances as a result of unreasonable expense or in any other way.