Heating that lives under the floor — beside the glass
Trench convectors are recessed hydronic units installed flush into the floor — typically running along floor-to-ceiling windows or sliding doors. They create a curtain of warm air up the glass surface, eliminating cold drafts and condensation without taking a single wall.
Designed for specific architectural moments
Trench convectors aren't a general-purpose emitter — they're the right answer for a particular kind of room. If your home has any of these features, they're worth considering.
Floor-to-ceiling glass
Large windows and sliding doors look incredible — but they leak heat, attract condensation, and create cold drafts at the perimeter. Trench convectors solve all three.
Minimalist walls
If the architecture demands clean, unbroken walls — no panels, no vents, no visible heating equipment — trench convectors stay completely below sightline.
Open-plan living
Big living-dining-kitchen zones with few interior walls give you nowhere obvious to mount radiators. Floor-mounted convectors fit anywhere.
Condensation problems
If your glass fogs up in winter or you see water pooling at the base of doors, the convective air curtain dries the surface and prevents both.
A continuous loop of convected warmth
Trench convectors use natural convection — no fans, no noise, no moving air. Hot water from your boiler or heat pump flows through finned heat exchangers inside the floor cavity. The grille on top lets cool room air drop in, get warmed, and rise back out.
Cool air near the floor — especially the cold air dropping from glass surfaces — falls through the grille into the trench.
Hot water circulating through the finned coil heats the incoming air silently and continuously.
The heated air rises out of the grille, forming a convective curtain that pre-warms the glass surface and blocks drafts before they enter the room.
The only visible part — match it to the floor
Below the grille, everything's hidden in the floor cavity. The grille itself comes in a range of materials to suit timber, tile, stone or polished concrete finishes — so the convector either disappears or becomes a deliberate design feature.
Brushed metal
Aluminium and stainless steel grilles in matte, satin or polished finishes. Pairs cleanly with tile, polished concrete and contemporary architecture.
Timber inlay
Hardwood grilles designed to blend into timber flooring — oak, walnut, blackbutt and other species available to match your floor.
Anodised dark
Black or anthracite grilles for dramatic contrast against light floors, or to recede into dark stone, charcoal tile and moody interiors.
What you should know up front
Trench convectors are an excellent solution for the right home — but they're not the right answer for every room. Here's what we discuss with every client before recommending them.
If the trade-offs don't fit your home, we'll guide you toward radiators, underfloor, or a hybrid arrangement.
Get a Free AssessmentThings to weigh up
Trench convector questions answered
Can trench convectors heat an entire room on their own?
Usually yes — but they work best when paired with the architecture they're designed for. Along a full glass wall they'll heat a large open-plan space comfortably. In a small or boxed-in room they can be underspecified, in which case we'd typically combine them with radiators or underfloor heating elsewhere.
Will they really stop condensation on the glass?
Yes — this is one of their original purposes. By creating a continuous upward flow of warm air along the inside face of the glass, they raise the surface temperature above the dew point and prevent moisture from condensing. They also reduce the cold-air downdraft that makes rooms with large windows feel draughty.
Can they cool as well as heat?
Yes — when chilled water from a reverse-cycle heat pump runs through them in summer, they provide gentle background cooling. It's not as powerful as a dedicated split or ducted system, but it's a useful contribution to year-round comfort, especially in shaded glass-walled rooms.
How deep does the floor cavity need to be?
Typically around 150mm including the unit, insulation and clearances — though it varies by model and capacity. This means trench convectors are easiest to install during construction or a major slab-level renovation. Retrofitting into an existing floor is technically possible but usually means lifting and rebuilding the floor in that section.
How often do they need cleaning?
The grilles need a vacuum or brush every few months — dust collects in the airflow path and reduces efficiency over time. Many of our grilles lift out easily for deeper cleaning once or twice a year. We cover this in the handover when we commission the system.
Can I use them alongside radiators or underfloor?
Absolutely — most of our installs use trench convectors along the glass walls and either radiators or underfloor heating elsewhere. The boiler or heat pump runs the whole system as one. See the hydronic system overview for how the parts work together.
Do they work with both gas boilers and heat pumps?
Yes — they're standard hydronic emitters and run from any compatible water source. Heat pumps are ideal because trench convectors run efficiently at lower flow temperatures. See our electric heating page for heat pump details.
Designing around glass walls?
Book a free assessment and we'll review the architecture, recommend the right trench convector layout, and design it into the rest of your hydronic system.