Short answer
Choose a combi oven by meals per service first (6, 10 or 20 pans), then fuel (electric or gas), then the electrical service on site (208/240V or 480V, single or three phase). Confirm water quality for steam generation and the ventilation your local code requires before ordering.
Start with meals per service, not oven size
Count the meals you produce in the busiest service and the menu items that go through the oven. As a rough guide, 6-pan units serve smaller kitchens and satellite sites, 10-pan units serve mid-size restaurants, hotels and care homes, and 20-pan roll-in units serve hospitals, universities and banquet kitchens. Two smaller ovens can be more flexible than one large unit, because they can run different modes at the same time.
Half-size or full-size pans
U.S. kitchens mostly use hotel pans and sheet pans. Full-size models take full-size sheet pans; half-size models take half-size pans and fit tighter spaces. Check that your existing pans, racks and transport carts fit before choosing.
Electric or gas
Electric combi ovens are simpler to install where enough power is available. Gas models need a gas connection and usually still need electrical power for controls and fans. The choice often follows the utilities already in the kitchen and local energy costs.
Match the electrical service
Full-size electric models are commonly offered in 208/240V and 480V three-phase versions. The model code changes with voltage, so the version must be specified at order. Your electrician should confirm voltage, phase and available amperage on the circuit.
Water quality and steam generation
Steam is generated either in a boiler or by injecting water into the cooking cabinet. Hard water leaves scale and shortens component life. A water analysis before installation tells you whether a softener or filtration system is needed.
Ventilation and clearances
Ventilation requirements depend on the model, the fuel and your local code. Your mechanical engineer or code official decides whether a hood is required. Leave the clearances specified by the manufacturer for service access.
Questions to ask before you buy
Which listings does the exact model code carry (for example UL and NSF)? How are installation and commissioning handled? Which accessories are needed for your menu? Who provides warranty service at your location?
Equipment covered in this guide