Terraced house built in 2002, energy rating B, underfloor heating - heating replacement

Hello everyone,

we can purchase a terraced house built in 2002
- 120m2 living space on 3 floors
- WBS 13cm Styrofoam on exterior wall, double-glazed windows
- Energy consumption certificate B
- Gas boiler (condensing boiler Brötje Ecocondens BBS15) produces hot water and heats, 150l storage
- Underfloor heating in all rooms, local thermostats on the wall (they are rotary controls like on a radiator in each room)

The gas heating is therefore about 20 years old, presumably regularly serviced, no known repairs.

With the current new framework conditions for heating, I have the following questions
- what lifespan would you assume for such a device? Is it likely to break down in the near future? If I have to renovate anyway, should I renew/replace it right away?
- what costs would you estimate if it had to be replaced due to defect by a new gas heating system?
- should I then switch directly to a heat pump heating system?
Since there is underfloor heating everywhere, I think operation with a heat pump should be possible, but probably with a larger storage tank (household with 4 people).

The installation space is limited at the location; there is still a few square meters of free space in the basement. Between the current installation location and a possible alternative place in the basement there are about 15m of piping—can this be extended with insulated pipes?

Is a split system with an outdoor unit in any way subject to approval or only realizable with minimum distances / can the neighbor block it?
If yes, could a fully indoor unit represent a possible solution? There would only be supply and exhaust air ducts, the rest is inside the house, right?

The shed roof has 45m2 area for solar panels; combined with a storage system, this could possibly reduce the energy demand further.

So far my considerations. Am I missing something fundamental?

For implementation including installation, I currently estimate
- replacement of gas boiler by heat pump + water storage 15-20K EUR
- solar 8kWp + 5kWh storage 20K EUR
do you consider this realistic?
Does such a replacement make sense technically and financially?

I would appreciate any input, I am still quite new to these considerations and probably won't get any further without expert advice.
Maybe someone has experience or expertise to evaluate these basic ideas.

First of all, the question is what kind of energy consumption the house has and with what laying distances the underfloor heating was installed or what supply temperature you have in winter.

With the current new conditions for heating, the following questions arise for me
- what lifespan would you assume for such a device? Is it expected to break down soon? If I have to renovate anyway, should I renew/replace it right away?

The question is like asking a 94-year-old grandmother how long she has left to live. The answer can range from "until tomorrow" to "at least another seven years."

- what costs would you estimate if it has to be replaced due to defect with a new gas heating system?
- should I then switch directly to a heat pump heating system?

Costs? A smaller single-digit thousand euro amount.
Switch to heat pump? I would do it if it makes sense ==> see initial questions. It makes no sense to replace €3,000 gas costs with €2,700 electricity costs.

The installation location is limited in space, there are still a few square meters free in the basement. There are about 15m of piping between the current installation location and a possible alternative location in the basement; can this be extended with insulated pipes?

Is a split system with an outdoor unit subject to approval or only feasible with minimum distances / can the neighbor block it?
If yes, could a completely indoor system be a possible solution? Here there would only be supply and exhaust air pipes; the rest is inside the house, right?

In BW, there are no minimum distances to the property boundary. Only certain noise levels must be taken into account. Piping lengths play no significant role. By the way, there are also monoblocks that can be simply connected to the old pipes.

For implementation including installation I currently estimate
- replacement of gas boiler with heat pump + water tank 15-20kEUR
- solar 8kWp + 5kWh storage 20kEUR
do you consider that realistic?
Does such an exchange make technical and financial sense?

Heat pump + installation largely depends on what and how is installed. However, the budget could be quite too small with the renowned Vaillant & Co. I would go for a monoblock there.
Photovoltaics always as large as possible to achieve scale effects. The 8kW system is (for the storage) too small and absolutely much too expensive compared to, for example, a 15kW system.

Thank you for the response!

I will try to find out details about the current heating system in the next few days.
Regarding the solar power: I roughly estimated 8kW for my 45m2 roof area, is 15kW even possible there?

Discussed today whether a domestic hot water heat pump could make sense to avoid using gas in summer. That would mean later installing another heat pump if the gas heating is to be eliminated / has to be eliminated?

Ask the owner about the maintenance contract. The one who has done the maintenance so far will help you further. After 20 years, getting spare parts is often hardly possible anymore. The installers might still have removed devices as spare part donors.