This term appears on premium radiators in this family, and it describes a real, physical difference from a basic convector — not just marketing language.
The core stores heat, and releases it slowly
The Bestherm ALBA uses a ceramic dry-inertia core; the Noirot Radiaflo heats mineral oil with an immersion resistance. Both mediums absorb heat from the element and continue radiating it into the room for a period after the element itself switches off.
Compare that to a basic convector
The Alpina CHYO2, a straightforward convector with no stated inertia core, cools essentially as soon as it’s switched off — there’s no thermal mass storing and releasing heat afterward.
What it changes in practice
A room heated by an inertia radiator tends to hold a more even temperature, with the element cycling off for longer stretches while stored heat maintains warmth, rather than the sharper on/off temperature swings a basic convector can produce.
Fluid versus ceramic — neither is stated as superior
Noirot’s mineral oil and Bestherm’s ceramic core are both genuine, established inertia designs. Neither manufacturer publishes comparable data that would let one be ranked above the other on how long or how evenly it holds heat.
What we would not do
Claim thermal inertia is simply “more efficient” without a manufacturer figure to back it. What’s documented is a different heat-release pattern — smoother, longer-lasting warmth after the element cuts out — not a stated percentage saving on your bill.
Check your own manual before you follow anything here. Humidity ranges, wattages, voltage and current ratings differ from model to model, and the manufacturer's figures take precedence over anything written on this site. We report what makers and monitors publish — a target humidity percentage, a heater's tip-over and overheat protection, a plug or thermostat's maximum load rating — and we never turn a reading into a health verdict or a diagnosis. Questions about air quality and health are matters for a qualified professional and your national health authority, and this site points you to them rather than restating them. Where wiring, voltage or load ratings are involved, matching them exactly to your appliance is a safety matter, not a technicality.
The questions that keep coming up
Does thermal inertia save money on electricity?
It can change the pattern of running cost — the radiator cycles its element off for longer stretches while stored heat keeps the room warm — but neither manufacturer we've reviewed publishes a percentage saving, so we won't invent one.
Last reviewed 24 August 2026