In Brussels, on Avenue Louise, we renovated the collective boiler room of two buildings — replacing two old oil boilers with two gas condensing boilers in cascade.
The context
Two 1970s buildings, around 2,000 m² and 18 apartments, heated by an ageing oil boiler room: a 250 kW boiler for heating and a second 226 kW boiler for hot water — nearly 476 kW installed, heavily oversized and energy-hungry.
A decision based on an energy audit
Rather than replacing like-for-like, the choice was based on an independent energy audit (Solecolux). The figures were clear: hot water ran on a 226 kW boiler where about 30 kW is enough, and the heating was oversized by at least 20%. Deciding on real data, not guesswork.
The installed solution
- ✅ Two Buderus Logano plus GB272 gas condensing boilers in cascade (~100 kW each), replacing the two oil boilers.
- ✅ A drastic reduction in installed power: from about 476 kW on oil to ~200 kW on gas — the right output at last.
- ✅ Cascade for continuity: if one boiler stops, the other takes over — no heating or hot-water interruption for the 18 apartments.
- ✅ Moving away from oil (installing new oil boilers is now banned in Brussels) to condensing gas, cleaner and more efficient, with a flue liner.
- ✅ Protecting the installation: sludge and air separators, heat exchanger and hydraulic decoupling to protect the new boilers.
Hot water, done smarter
The building already had a heat-pump water heater. We integrated it as preheating for the domestic hot water: cold water is gently warmed for free using energy from the air before entering the tank heated by the boilers. When consumption is high and preheating sufficient, the boilers work that much less.
A project carried out with Aetra
This project was carried out in collaboration with Aetra. Renovating a collective boiler room takes coordination — study, sizing, careful execution in an occupied building — and that's exactly what we love to do.
A similar project?
Do you manage a co-ownership, a property syndic or a collective building? Our advisors carry out a free assessment for the best boiler-room solution. Call us on +32 15 62 70 80.