ᐅ Which heating system is best for an older apartment?

Hello, I have purchased an old apartment (60m² (645 sq ft)) that has a more than 25-year-old Vaillant gas boiler (for heating and instantaneous hot water). I would like to replace it with a new, modern heating system.

The chimney sweep told me on site that I cannot install a condensing boiler because the chimney serves three apartments, and all of them would then need to have condensing boilers due to the chimney arrangement.

I am now looking for a gas boiler that is as economical as possible (non-condensing), compact, wall-mounted, and above all quiet, while also providing a sufficient amount of hot water (in my old apartment, the water pressure during showers always seemed too low).

Does anyone have a recommendation?
Regards, Ingo

There is really a lot happening in the forum—asked 3 questions and after 3 days not a single answer, impressive! 🙄

Hi Ingo,
the problem is not the pressure but the physics. Even the smallest gas boiler has enough capacity for your apartment, but it only produces moderately warm water. With an 18kW boiler, you get about 5 liters (1.3 gallons) of hot water per minute in a continuous flow system. So, if you want very good hot water performance, you need a combi boiler with a hot water storage tank—that is, a tank that stores hot water. Provided you have enough space for it.
Regards, Scarfy

Ingo.M schrieb:

.....Does anyone have a recommendation?...

Yes, first conduct (or have conducted) a basic assessment. => Actual demand (capacity, energy) for heating and hot water!

Best regards

Thanks for the replies. The current heating system has a capacity of 19/23 kW, but a smaller one would be sufficient. The chimney inspector mentioned 11 kW (which would allow a condensing boiler with a flue directly through the wall). However, my 19 kW gas boiler (condensing) in the old apartment definitely produced too little water pressure; even with a special showerhead, there was no massage jet, more like a moderate summer rain 🙄.

The new heating system is supposed to be installed in a niche above the washing machine. The available space is at most 70 cm (28 inches) wide and 60 cm (24 inches) deep (preferably less, so I can still place something on top of the washing machine). The ceiling height is just under 2.5 m (8 feet). Another option is above the toilet directly on the chimney, but in that case, the unit would have to have an extremely low depth (max. 30 cm (12 inches)).

I will look into what options there are for hot water storage tanks.

Actually, I’m not in favor of hot water tanks for keeping water heated all day for at most two uses per day 😎 (and tankless electric water heaters are out of the question). Is there any combination unit that offers, for example, 11 kW heating capacity but 30 kW hot water output?

Regards, Ingo