ᐅ Renovating a Gas Heating System – What Are the Costs?

Ok, I understand – then you can hardly just have quotes sent to you; you really need to bring the people on-site.

What can I say about that: I have received all our quotes confirmed in writing by mail. This can be quite important later on if the costs end up being higher. It should be obvious that someone needs to inspect the site beforehand.

Sure, and I had agreed with you, so you didn’t have to say anything more 😉

ed55 schrieb:
...Euro, of course this is about the investment, as with the other figures I mentioned.

This is a clearly one-sided view. For this, you could use the cheapest gas condensing boiler available on the market.
If the actual demand (capacity, energy) for heating and hot water is not known, the likelihood of making a poor choice is relatively high.
In older systems, the actual annual efficiency is usually between 40% and 60%, meaning that 40% to 60% of the energy used provides no benefit, only cost ;-)
Utilities bill based on condensing heat value, not the lower heating value. This alone theoretically accounts for 11% of the energy demand for heating and hot water! If condensing heat is not optimally used, theoretically at least 11% is lost with "zero" benefit.
Theoretical efficiency rates (colorful marketing brochures) of around 85% are practically never achieved, even in new systems!
With optimal design, sufficient planning, and correct sizing, about 80% can be reached, but then everything must be right!
Often, even these remain around 55% to 65%, raising questions about the sustainability of the new investment.

Now calculate the consumption costs over 20 to 25 years with an energy price increase of about 5%, then you will know the real value of a senseless, randomly selected boiler for 1,000 € ;-)

Best regards

Euro, on the one hand, you say that the old systems only achieve a low annual utilization rate, but on the other hand, even new ones do not reach the specified efficiency values.
This would argue against investing in a more complex (condensing) technology; after all, the boiler alone isn’t the complete solution.
In this specific case, it is also possible that the apartment will be rented out, so a potentially 20-year period of more efficient use may not benefit the investor.

ed55 schrieb:
€uro, on one hand you say that old systems only achieve a low annual utilization rate, but on the other hand, new ones do not reach the specified efficiencies either. ...

Utilization rates refer to energy-related performance, whereas efficiencies relate to performance-based instantaneous measurements. There is a huge difference between the two!

ed55 schrieb:
....That would actually argue against using advanced (condensing) technology; the boiler alone isn’t the whole solution....

New investment in condensing technology is worthwhile, but only if the benefits of condensing are actually realized in practice. For new installations, this is no problem, as the mechanical and plant engineering planner designs heat distribution and hydraulics accordingly, provided they have the necessary expertise.
In existing buildings, the situation is completely different! A simple, unconsidered replacement could become a money pit.
In addition, one should clearly differentiate between owner-occupancy and rental situations. For owner-occupiers, the long-term relationship between investment costs and consumption expenses is important.
For rental properties (excluding utilities), the landlord is generally not interested in the consumption costs borne by the tenant ;-) From an economic perspective, it would be almost irresponsible to invest here ;-)

best regards