Consultation on heating when buying a house - is replacement necessary?

Hello everyone,

this situation came as quite a surprise to me: I have the chance to buy a property in a perfect location. The offer only came this week, and after today's viewing, I am close to making a decision.

It is a detached bungalow from 1993 with 80 m² of living space and a basement. However, I noticed the energy demand of almost 200 kWh/m²a, which seems quite high. Another issue is the gas heating system including the boiler, which has been installed since the house was built. On the one hand, it does not seem very efficient, on the other hand, I am unsure about the legal situation regarding it. My questions are:

As a new owner, am I obliged to renew the gas heating system because the house dates from 1993? The realtor said it is not a problem, but my own research is contradictory.
If yes, do I have to equip the new heating system with a share of 65% renewable energies (E65)?

Ideally, I would like to use the current heating for the coming winter and only convert to a new gas condensing boiler in 2025. This would keep the costs low. I plan to stay in the house for only 5–6 years anyway, so I accept that the consumption will be somewhat higher.

Does anyone have experience with the current legal situation or tips on how I should best approach the situation? I am grateful for any help!

Best regards

Am I obliged as a new owner to renew the gas heating system since the house is from 1993?

No, provided it is a condensing or low-temperature gas heating system.

I would actually prefer to use the current heating system for the upcoming winter and only convert to a new gas condensing boiler in 2025. That would keep the costs low. I plan to stay in the house for only 5–6 years anyway, so I accept that the consumption will be somewhat higher.

Then keep the old heating system as long as it works and preferably until you move out.