Pellet silo and buffer tank: plan them at APS for a new biomass build in Luxembourg
How to size silo, buffer tank and technical room at APS, and qualify for Klimabonus 2026 (up to €8,000).
Why size the silo and buffer tank at APS?
Luxembourg's Klimabonus 2026 grants up to €8,000 to a pellet boiler in a single-family home (€4,000 without replacing an old installation), plus a +15% bonus when a buffer tank is installed and a flat €1,000 when combined with solar thermal. These bonuses are never retroactive — they must appear in the grant file at submission.
For multi-unit housing, the grant rises to €6,000 per dwelling (capped at €40,000). Logistics become critical: blower-truck access, hose run, silo geometry all need to be fixed at APS, not after the building permit.
- Add a ≥ 50 × 50 cm silo hatch before pouring the slab.
- Dedicated power supply + separate combustion-air duct.
- Keep the blower-hose run ≤ 20–30 m to limit pressure losses.
How many m³ of silo do you need?
ENplus A1 pellets weigh about 650 kg/m³. A 150 m² passive house uses only 300–500 kg/year (≈ 15 kWh/m²/year) — under 1 m³. A 1.5 m³ silo already covers 2–3 heating seasons.
For a collective building, think in truckloads: a standard blower-truck delivers 8–12 t, i.e. 12–18 m³. Plan 1–2 deliveries/year to amortise the blowing cost.
- Single-family: 1.5–3 m³ (≈ 1–2 t).
- Collective (10–20 flats): 12–18 m³ + HGV access.
- Always add 20% dead volume for the cone (45° slope).
How big should the technical room be?
A 15–25 kW pellet boiler is roughly 0.8 × 1.0 × 1.2 m. Add a 300–500 L buffer tank (Ø 60–70 cm × H 1.5 m) and service clearance. Plan 4–6 m² of floor area, silo not included.
EcoDesign (EU 2015/1189) and EN 303-5 Class 5 set minimum clearances to walls and require full access for the annual service.
- Door ≥ 80 cm wide for boiler and tank delivery.
- Floor load: 350–400 kg/m² (boiler + silo + buffer).
- High and low ventilation, as per the Tatano manual.
Seasonal efficiency and maintenance: what to plan now?
A Class 5 pellet boiler reaches 88–92% seasonal efficiency (PCI) — the threshold that unlocks Klimabonus. To keep that level over 15–20 years, yearly maintenance is non-negotiable: heat-exchanger cleaning, ash removal, fan and flue checks.
At design stage, provide clearances for the ash pan, a siphon, and a slot for the service contract (1–2 h/year, Tatano-approved technician in Luxembourg). It's a concrete reliability argument for the client.
- 1–2 h/year servicing + chimney sweeping.
- Buffer tank = fewer cycles, less wear.
- Stack municipal top-ups via the Klima-Agence simulator.
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