Compact, reliable, cheap to buy. We tell you honestly when gas still pays off in 2026 — and when it doesn't.
A gas condensing boiler burns natural gas and — unlike old non-condensing boilers — also uses the condensation heat of the water vapour in the flue gas. The flue gas is cooled down far enough for the water vapour to condense and transfer its heat to the heating water. The result: efficiencies close to the theoretical limit, ten to 15 percent savings compared to an old boiler — with the same gas connection.
Modern units like the Vaillant ecoTEC series modulate continuously down to below 2 kW: instead of constantly switching on and off, the boiler adapts to the actual heat demand — quieter, more economical, longer-lasting. As a Vaillant Premium Partner we have installed the series for years, keep common spare parts in stock and service your system annually.
The legal situation since July 2026: installing a new gas heating system is fully permitted again under the Building Modernization Act. But: from 2029 new gas heating must use a share of bio fuels (10%, rising to 60% by 2040), and the CO₂ price moves into European emissions trading in 2027 — heating with gas is set to become predictably more expensive. That's exactly why we advise you honestly before you buy, instead of just selling.
Despite everything, there are cases where we recommend a gas boiler with a clear conscience:
In all other cases we calculate the comparison with a heat pump openly — with your figures, not brochure values.
Vaillant documents for the units we install most often. All downloads collected on our downloads page.
Call, book an appointment or write to us — whatever you prefer. We reply within one business day, usually faster.
