Quick Answer
A convection oven cooks with fan-driven dry heat; a combi oven adds steam, so it can roast, steam, or combine both. In the UK, countertop convection ovens start at around £500 to £800, refurbished heavy-duty models sit around £1,400 to £1,750, and new combi ovens typically run from about £5,300 for a 4 or 5 x GN 1/1 model to £10,000+ for 10 and 11 grid electric units.
Caterzone supplies commercial combi and convection ovens to UK restaurants, cafés, pubs, hotels, schools, and contract caterers, and the question we hear most is whether a kitchen really needs a combi oven or whether a good convection oven will do the job. The answer depends on your menu, your volume, your power supply, and how much you are prepared to spend on water treatment and servicing.
This guide covers convection versus combi steamer, boiler versus boilerless steam, gastronorm capacity, gas versus electric, single-phase versus three-phase power, water treatment, installation, and running costs. If you are already comparing premium brands, our Rational vs Lincat combi oven comparison goes deeper on those two. Browse the convection oven collection as you read.
What is the difference between a convection oven and a combi oven?
A convection oven uses one or more fans to move hot, dry air around the cavity. Moving air transfers heat faster than still air, so food cooks more evenly and quicker than in a static oven, and you can load several trays at once without the top shelf burning while the bottom one stays pale. Convection ovens are excellent for baking, pastry, pizza, roast potatoes, reheating, and finishing.
A combi oven, or combi steamer, does everything a convection oven does and adds steam. Most models offer three core modes: dry convection heat, pure steam (typically around 30°C to 100°C), and combination mode, where steam and hot air run together at a controlled humidity. Combination mode is what makes a combi oven valuable: joints lose less weight in cooking, chicken stays moist, bread gets a proper crust, and plated or batch-cooked food can be regenerated without drying out.
Modern combi ovens also add core temperature probes, multi-stage programmes, HACCP data logging, and automatic cleaning. The Sammic CombiSteam HX-611D, for example, runs from 30°C to 280°C with a core probe function, a 10-inch touchscreen, and USB export of HACCP data. That is a very different tool from a 13A countertop convection oven, and it is priced accordingly.
Do you need a combi oven, or will a convection oven do?
Choose a convection oven if your menu is mainly baked goods, pizza, pies, jacket potatoes, chips finished in the oven, or reheated items, and you cook in modest batches. A café, coffee shop, sandwich bar, or small pub kitchen can do a great deal with a well-built convection oven, and the purchase and running costs are a fraction of a combi.
Choose a combi oven if you roast meat in volume, steam vegetables and fish, cook overnight, run banqueting or batch cook-chill, or want one appliance to replace a steamer, a convection oven, and part of your range. Kitchens serving 100 or more covers, hotels, care homes, schools, and contract caterers usually recover the cost through lower meat shrinkage, labour saved by programmes, and freed-up space.
There is a middle ground. Some convection ovens offer humidity injection or a "steam" function, and some entry-level combis drop the touchscreen and self-cleaning to cut cost. Blizzard's Simple Combi range, for instance, uses LED indication lights and straightforward controls rather than a full programmable screen. For a deeper look at how steam cooking works in practice, see our convection oven vs combi oven article.
Boiler or boilerless: how should a combi oven make steam?
A boiler combi has a separate steam generator that heats water and feeds saturated steam into the cavity. It produces steam quickly and in large volumes, which suits heavy steaming such as vegetables, rice, and fish at volume. The trade-off is more components, more scale build-up, a higher purchase price, and more servicing.
A boilerless combi, often called direct injection or spritzer, sprays water directly onto the fan or heating elements, where it flashes to steam. It is simpler, generally cheaper to buy and maintain, and uses less water. Steam output and saturation are lower than a good boiler system, but for most restaurant roasting, combination cooking, and regeneration it is more than adequate. Blizzard's 11 x GN 1/1 electric combi uses direct injection steam, and its Simple Combi models generate steam by a direct system.
As a rule of thumb, if steaming is a core part of your menu at high volume, look at boiler models. If you mainly roast, bake, and use combination mode, a boilerless combi is the sensible, lower-maintenance choice.
What size combi or convection oven do you need?
Combi ovens are sized by how many gastronorm containers they hold. A GN 1/1 pan measures 530 x 325mm; a GN 2/1 pan is 650 x 530mm. Common sizes are 4 or 5 x GN 1/1 (compact or countertop), 6 or 7 x GN 1/1, 10 or 11 x GN 1/1, and larger floor-standing 20 grid models. Rough guidance used across the industry is:
- 4 to 7 x GN 1/1: cafés, pubs, and restaurants up to around 50 to 80 covers, or as a second oven alongside a range.
- 10 to 11 x GN 1/1: busy restaurants, hotels, and schools serving roughly 80 to 150 covers per sitting.
- 20 x GN 1/1 or GN 2/1 floor-standing: banqueting, hospitals, and central production kitchens.
Treat cover counts as a starting point. Menu matters more: a kitchen that roasts every joint and steams every vegetable needs more grids than one that uses the combi only for finishing. Check shelf spacing too. Tray slides spaced 67mm apart, as on Blizzard's Simple Combi models, suit shallow GN pans; deep pans or whole chickens need you to skip a runner, which cuts usable capacity.
Convection ovens are sized by tray count and tray size. Small countertop ovens often take 4 trays around 440 x 315mm, as with the Blizzard 2670W glass-door convection oven. Larger models such as the Hamoki YSD-6A 100 litre oven or the refurbished Blue Seal Turbofan E31D4 accept four full GN 1/1 pans, which is important if you want to move food straight from oven to hot cupboard or bain-marie without decanting.
Combi and convection oven comparison
| Oven | Type | Capacity | Power | Price |
|---|---|---|---|---|
| Hamoki 62 litre convection oven (YSD-1AE) | Convection | 4 trays, 325 x 450mm shelves | 2.67kW electric | £509 |
| Blizzard 2670W glass door convection oven | Convection | 4 trays, 315 x 440mm | 2.67kW electric | £714 |
| Hamoki YSD-6A 100 litre convection oven | Convection | 4 x GN 1/1 | 2.85kW electric | £799 |
| Blue Seal Turbofan E31D4 (refurbished) | Convection | 4 x GN 1/1 | 3kW, 13A plug | £1,550 |
| Blizzard 5 x GN 1/1 Simple Combi | Combi, direct steam | 5 x GN 1/1 | Electric | £5,306 |
| Blizzard 4 x GN 1/1 Compact Combi | Combi | 4 x GN 1/1 | Single or three phase configurable | £5,650 |
| Blizzard 7 x GN 1/1 Compact Combi | Combi | 7 x GN 1/1 | Electric | £6,149 |
| Sammic CombiSteam HX-611D | Combi | Compact GN 1/1, core probe | 380–415V three phase | £7,800 |
| Blizzard 11 x GN 1/1 Electric Combi | Combi, direct injection | 11 x GN 1/1 | Electric | £10,296 |
Prices are as listed on the Caterzone store at the time of writing and include VAT. Installation, stands, water treatment, and extraction are extra where needed.
Gas or electric: which is better for a commercial combi or convection oven?
Electric is the more common choice for both combis and convection ovens in the UK. Electric models give very even heat, tight temperature control, and simpler installation where a suitable supply already exists. Small electric convection ovens often run on a standard 13A plug: the Blue Seal Turbofan E31D4 draws 3kW from a 13A socket, and the Hamoki ovens are rated at 2.67kW and 2.85kW.
Gas makes sense when your electrical supply is limited or expensive to upgrade, or when your kitchen already has a strong gas infrastructure. Gas convection ovens such as the refurbished Blue Seal Turbofan gas model (10kW gas, with a 13A cord for the fan and controls) give high heat output without a big electrical load. Gas combis exist but cost more and still need an electrical supply for fans, controls, and cleaning.
Any gas appliance must be installed, connected, and commissioned by a Gas Safe registered engineer, and commercial kitchens need to meet ventilation and gas interlock requirements. If your extraction does not include a gas interlock, budget for one before choosing gas.
Do you need three-phase power for a combi oven?
Many combi ovens do. Larger electric combis typically need a three-phase supply, and the Sammic HX-611D is specified at 380–415V three phase (3N). Some compact models can be configured for single or three phase; Blizzard's 4 x GN 1/1 Compact Combi is one. Countertop convection ovens up to about 3kW generally run from a 13A plug.
Before you buy, check the rated power and supply on the data plate or spec sheet, then ask a qualified electrician to confirm your board has spare capacity and the correct isolator. Upgrading a single-phase site to three phase can take weeks and cost far more than the oven, so this check belongs at the start of the project, not the week before delivery. Electrical installation work must comply with BS 7671, and portable appliances should be PAT tested.
Why does water treatment matter for combi ovens?
Steam means water, and much of England, particularly London, the South East, and East Anglia, has hard water. Limescale builds up in steam generators, on injectors, and on sensors, which reduces steam output, upsets humidity control, and eventually causes breakdowns. Most manufacturers recommend water treatment, and scale damage is a common reason for warranty claims being refused. Blizzard, for instance, suggests installing its 11 x GN 1/1 electric combi with a water softener.
The right treatment depends on your local water and the oven type. Options include softeners, scale-inhibiting cartridge filters, and reverse-osmosis systems. Check your water supplier's hardness figure for your postcode and follow the oven manufacturer's water specification. Filter cartridges need changing on schedule; an expired cartridge gives no protection.
Combis also need a drain connection, and self-cleaning models use detergent and rinse aid. Budget for chemicals, filter cartridges, and an annual service when comparing running costs.
What does a combi or convection oven cost to run?
Running cost depends on power rating, how long the oven is on, and how full it is. A 3kW convection oven heating for an hour and then cycling for six hours of service might use somewhere in the region of 8 to 12kWh a day; at 25p per kWh that is roughly £2 to £3 a day. Treat that as an illustration, since actual use depends on door openings, loads, and thermostat settings.
Combi ovens draw more power but often save energy overall because they cook faster, cook more in one load, and can replace several appliances. Practical habits make a big difference: preheat only when needed, load full, keep the door closed, use programmes rather than guesswork, and switch to standby rather than leaving the oven at full temperature through quiet periods.
New or refurbished combi and convection ovens?
Refurbished convection ovens from heavy-duty brands are often excellent value. Caterzone's refurbished Blue Seal Turbofan ovens sell for £1,400 to £1,750, and these ovens are built for years of daily service. Refurbished stock is tested and honestly graded, though B-grade units may carry cosmetic marks.
For combi ovens, the condition of the steam system and electronics matters more. A new combi brings a full manufacturer warranty, current software, and a clean steam generator. If you consider a used combi, ask about its water treatment history, descaling records, and the cost of key parts before buying.
Frequently asked questions
How much does a commercial combi oven cost in the UK?
New compact combi ovens start at around £5,300 to £5,700 for 4 or 5 x GN 1/1 models. Six to seven grid models typically cost £6,000 to £8,000, and 10 to 11 grid electric combis run from about £6,900 for a simple model to over £10,000 for a programmable one. Premium brands and 20 grid models cost considerably more.
Can a combi oven replace a convection oven and a steamer?
Yes. A combi oven offers dry convection heat, pure steam, and combination mode, so it can replace a convection oven and a standalone steamer, and often reduces how much you use the range oven. Many kitchens still keep a small convection oven for pastry or as back-up.
Does a combi oven need a water softener?
In most of the UK, water treatment is strongly recommended. Hard water causes limescale in steam systems, which reduces performance and can affect warranty cover. Check the manufacturer's water specification and your local hardness, then fit the softener or filter they recommend.
Can a commercial convection oven run on a 13A plug?
Many countertop models can. Ovens up to around 3kW, such as the Blue Seal Turbofan E31D4 or the Hamoki 2.67kW and 2.85kW models, are designed for a 13A socket. Larger convection ovens and most combi ovens need a hard-wired single-phase or three-phase supply.
Is a boilerless combi oven good enough?
For most restaurants, yes. Boilerless (direct injection) combis handle roasting, baking, combination cooking, and regeneration well, and they are cheaper to buy and maintain. Choose a boiler combi if high-volume steaming of vegetables, rice, or fish is central to your menu.
Where to buy a combi or convection oven in the UK
Caterzone stocks new and refurbished ovens from Blizzard, Sammic, Hamoki, and Blue Seal. Browse the convection oven collection, or go straight to the Blizzard 4 x GN 1/1 Compact Combi at £5,650, the Blizzard 7 x GN 1/1 Compact Combi at £6,149, or the three-phase Sammic CombiSteam HX-611D at £7,800. For larger kitchens, the Blizzard 11 x GN 1/1 Electric Combi is £10,296 and the Blizzard 10 x GN 1/1 Simple Combi is £6,921.
If a convection oven fits your menu, the Blizzard 2670W glass door convection oven is £714, the Hamoki YSD-6A 100 litre GN 1/1 convection oven is £799, and the refurbished Blue Seal Turbofan E31D4 is £1,550.
Still deciding? Read our Rational vs Lincat combi oven comparison and our convection vs combi oven guide. For help matching an oven to your menu, power supply, and water, call Caterzone on +44 7787 069044 or email info@thecaterzone.co.uk.
