A combi oven does two jobs in one chamber: it roasts with dry convection heat and it cooks with steam, blending the two in combination mode. Most models carry two separate heating systems — elements for the cavity, and a steam generator for humidity — and each system needs its own temperature control and its own safety limiter. The chamber is also the wettest environment in the kitchen: saturated steam while cooking, then a wash cycle that floods it with water and detergent. This guide works through the control points on a combi oven and the parts that suit each one. Mechanical capillary control serves the heating circuits — cavity elements and boiler; the fine low-temperature steam programs of a modern combi remain electronic territory.
Two heating systems, two control jobs
The cavity circuit is a convection oven: fan-circulated air, working from gentle steaming temperatures up to roughly 300°C at a full roast. Its control cycles the main elements against a bulb in the chamber airstream — the same duty as a standalone convection oven, covered in our oven thermostat guide. What differs is everything around it: the chamber air is often saturated, and the door opens into clouds of steam.
The steam generator is a second machine hiding in the same cabinet. Boiler models heat a small tank of water with its own elements, and the boiler control holds that water at boiling so steam is available on demand. Boilerless models spray water onto the hot cavity elements instead — there is no second circuit, but the cavity elements and their control then carry the steam duty as well and cycle far more often. Know which design you are servicing before you specify parts: a boiler model has four control points (cavity control and limiter, boiler control and limiter); a boilerless model has two.
Steam and wash cycles: control in a wet chamber
A sensing bulb in a combi cavity lives in condensing steam for hours a day, and the nightly wash cycle adds detergent solution and rinse water. Standard sensing parts tolerate moisture, but permanent humidity plus chemical wash-down is exactly the duty waterproof sensing is built for: the TY316 waterproof variant (16A, 50–380°C) covers cavity control, and the TY316-8 brings the same waterproof construction to a manual-reset limiter tripping at up to 380°C.
Placement still matters. Keep the bulb in the chamber airstream but out of the direct wash jet and steam inlet path, and route the capillary so condensate drains away from the control body rather than into it. The seating and routing rules are in our installation guide.
Three-phase loads and multi-pole switching
Combi ovens are among the heaviest electric loads in a commercial kitchen, and most are three-phase. Switching all three phases on one control keeps the elements balanced and the load evenly drawn: the AG32-3K three-pole control (16A / 32A / 50A, up to 400V, 50–350°C) is built for that duty. Smaller single-phase combis and boiler circuits sit inside the AG16-K (50–400°C, 16A / 20A), or step up to the AG32-1K (up to 32A, single-pole compulsory OFF).
| Model | Rating | Range | Reset |
|---|---|---|---|
| AG16-K | 16A / 20A · 110V / 250V | 50–400°C | Automatic |
| TY316 | 16A · 110V / 250V | 50–380°C | Automatic |
| AG32-1K | 16A / 20A / 32A · 110V / 250V / 380V | 50–450°C | Automatic |
| AG32-3K | 16A / 32A / 50A · 110V / 250V / 400V | 50–350°C, three-pole | Automatic |
Technical data is a catalogue reference. Confirm final ratings, dimensions and approvals for the selected model before ordering.
Limiters for the cavity — and for the boiler
Each heating system needs its own independent manual-reset limiter. On the cavity, the limiter guards against a failed control at full roast: the AG32-1S, its trip point factory-set to your specification, or the three-pole AG32-3S (tripping at up to 400°C) where the control is three-pole. A limiter that only watches the cavity does nothing for the boiler — and the boiler is the circuit that can run dry.
A steam boiler that loses its water feed with the elements live will overheat fast. Its limiter must cut the boiler circuit completely and stay cut until someone checks the water level: the AG32-2S double-pole manual-reset limiter (tripping at up to 400°C) is that device, and its 20A / 250V variant is built for water-heating duty. Set each limiter’s trip above its circuit’s maximum working temperature and below the damage point of insulation, seals and wiring; our safety limiter guide works through the setting logic, and our specification guide covers the full ordering checklist.
Certifications
Our thermostats are produced under a TÜV-certified quality system — certificate R50309054 (EN 60730-1 / EN IEC 60730-2-9), verifiable on Certipedia. Confirm the approvals carried by the specific models you select.
FAQ
Does a combi oven need one thermostat or two?
Two control points on a boiler model — one for the cavity, one for the steam generator — and each circuit needs its own independent manual-reset limiter as well. Boilerless models make steam on the cavity elements, so they run a single control point, but that control and limiter carry the combined duty.
What protects the thermostat in a steamy, washed-down chamber?
Waterproof sensing. The TY316 waterproof control (50–380°C) and the TY316-8 waterproof manual-reset limiter are built for wet environments; seat the bulb out of the direct steam jet and wash spray, and route the capillary so condensate drains away from the control body.
Which limiter suits a combi oven’s steam boiler?
A manual-reset limiter that cuts the boiler circuit completely — the AG32-2S double-pole limiter, tripping at up to 400°C, with a 20A / 250V variant built for water-heating duty. Manual reset matters here: it forces a water-level check before the boiler can fire again.
High-Current Control Thermostats · Manual Reset Safety Limit Thermostats · Capillary Control Thermostats