Which gas boiler should be planned for new construction?

Hello,

we are planning the construction of a single-family house according to the Energy Saving Ordinance, 140 sqm without a basement. We have decided on a gas boiler with solar and underfloor heating.

The builder installs Viessmann or Buderus.

Is it worth investing the additional costs for the "higher quality" boilers (Vitodens 300 / GB192i)? These have, among other things, better modulation and automatic combustion control than the basic devices (Vitoden200 / GB172).

Best regards

We will have the Buderus GB 172 installed. I also asked the heating company about the 192i; the surcharge for that was €500 net, so nothing dramatic, but he said the 172 does exactly the same as the 192, the 192i just looks a bit nicer because of the glass and the integrated WLAN module. We preferred to spend the money on the tube system instead of flat collectors and on a larger fresh water storage system.

We have the Vitodens300 and have been very satisfied for 4 years.

Did you choose the Vitodens300 because of the technical data (modulation etc.) and not the Vitodens200?

What is your annual consumption for what house size?

We chose the heating system because it
1. was the test winner at Stiftung Warentest
2. comes from Thuringia (regional approach)
3. because it did not cause any additional costs above the fixed price. Of course, the heating installer/site manager was shocked when I requested it, but I ultimately got it — it just had to come off their margin...

Size: 111 sqm living area.
KFW standard: 55
Outer wall: 36.5cm Ytong // Lambda 0.2 W/m²K
Floor slab insulated with XPS // 0.21 W/m²K
Ceiling in the upper floor sloping with 24cm // ceiling insulated with 34cm mineral wool // 0.12 W/m²K
The door + windows are triple glazed and gas-filled // total including frame 1.05 W/m²K

Heat generator:
Gas condensing boiler: Viessmann Vitodens 300
System control: Vitotronic 200
Solar 5 sqm: Vitosol 200-F
solar storage: Vitocell 100-W 300 liters
Underfloor heating

The solar system is only for hot water (without heating support)
Our gas boiler is switched off for heating from May to September and uses about 100 kWh over the summer.
In winter, the solar system hardly manages to heat the hot water (2 people), so it mostly runs on gas.

Ventilation runs via decentralized Lunos e² with 90% heat recovery.

Annually, we have a consumption of ~7600-8100 kWh gas for heating + hot water.
That is monthly €28 - €33 heating costs for the house. (Currently back to €28, winter probably wasn’t that cold)

We have 23°C set throughout the entire house (24-25°C in the bathroom), no night setback. Ventilation always on, no longer daily shock ventilation throughout the house (construction moisture gone long ago)