Imagine a luxury villa or a modern office building. The architect has designed enormous floor-to-ceiling glass facades for an unobstructed view. Where do you put radiators when there is no wall?
This is where Trench Heaters come in - "hidden" radiators or small Fan Coils literally buried inside the floor slab. The only visible element: an elegant, elongated grille running parallel to the glass.
Inside the metal trough beneath the floor sits a heat exchanger - a copper coil with aluminium fins - through which the hot water from the Heat Pump or boiler flows.
In winter, the massive glass pane is ice cold. The air touching it cools, becomes heavier, and "slides down" towards the floor creating a permanent, freezing draft at your feet (cold downdraft). Without intervention, this current floods the entire living room.
As soon as the cold air reaches the floor, it is "sucked in" through the grille of the channel. There, it passes through the hot exchanger and is heated instantaneously. The warm air (lighter) is propelled upwards, directly in front of the glass.
A continuous, invisible "curtain" of warm air is created right in front of the glass facade. This curtain "kills" the cold downdraft before it even enters the living space, while simultaneously preventing steam from fogging the windows (condensation).
A floor channel is 15-30 cm wide and 8-15 cm deep. It requires planning during construction - the engineer leaves a recess in the concrete slab. The length runs parallel to the entire glass facade (1-6+ metres).
These channels have no motor whatsoever. They rely 100% on the laws of physics: warm air rises, cold air descends. The movement happens automatically, without assistance.
No moving parts - zero noise. They never break down, require no maintenance, and consume no electricity. They need only hot water. Ideal for bedrooms and libraries next to large windows.
Without a fan, the thermal output is lower. They are not sufficient on their own to heat an entire living room. They usually function as supplementary heating: you have underfloor heating in the room, and the channel only cuts the chill from the glass.
Homes with underfloor heating + large windows. The natural convection channel does not replace the primary heating - it simply eliminates the cold downdraft and window condensation. Minimal running cost (zero electricity).
Because it provides heating only (no cooling), no condensate drain is needed. The installation is simpler and cheaper - just two water pipes (flow-return) and the metal trough.
Here, inside the channel sits a long, cylindrical cross-flow fan that sucks and forces air aggressively through the heat exchanger. In practice, it is a hidden Fan Coil inside the floor.
Fan-assisted channels deliver many times more Watts compared to natural convection types. They can heat an entire living room on their own, without any additional heat source. Ideal for large openings in commercial buildings.
When connected to a Heat Pump, they can also provide cooling! In summer you send chilled water (7-10°C), the fan blows cool air upwards - effectively like a low, invisible Fan Coil.
Due to the fan, there is a slight hum (25-35 dB on low speed). Modern units with EC/inverter motors keep noise exceptionally low - but they are not 100% silent like natural convection types.
When cooling, the chilled exchanger produces condensate (water). A drain must exist within the recess - exactly as with Fan Coils. The engineer must plan this from the start of construction.
The only visible part of this system is the grille. And here the options are superb - engineered so you can walk on them without fear of breakage (designed for 80-150 kg/m²).
Made from solid hardwood (oak, beech) that roll up for easy removal and cleaning. They blend perfectly if the room has a timber floor - making the channel practically "invisible."
Available in various finishes (natural, black, satin). Ideal for modern, minimal spaces or when the floor is tile, microcement, or terrazzo. Lightweight, durable and effortless to clean.
Ultra-durable, chosen for commercial spaces or office buildings with heavy foot traffic. They withstand heavy footsteps, heels, trolleys - without scratching or deforming. The most expensive but also most resilient option.
Because it is a hole in the floor, channels collect dust, hair, crumbs. Fortunately, the grille lifts off easily by hand. You vacuum the interior - this maintenance must be done regularly (every 1-2 months).
🏢 Trench heaters eliminate bulky radiators, showcase the view, and create an invisible "wall" of warmth exactly where the building hurts most: in front of massive glass facades.
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