Replacing a commercial oven is a kitchen project, not an appliance swap. Before you order, confirm four things about the new oven: the fuel and power it needs, whether it fits the space and clearances, whether your ventilation can serve it, and who is qualified to connect it. Get those right and the changeover can take a day or two. Get them wrong and you can end up with an oven on a pallet that nobody can legally switch on.
This guide is for owners and managers of bakeries, cafes, restaurants and catering kitchens in the UK. It covers when to replace rather than repair, what to survey, how to compare models on running costs, and how to plan the changeover so service barely stops.
TL;DR
- Treat the replacement as a system check: fuel, input rating, dimensions, extraction, make-up air, drainage and water all need confirming before you order.
- Gas ovens must be fitted by a competent Gas Safe registered engineer. Check their card and appliance competency before work starts.
- A new electric oven can exceed your site’s supply. Large combi ovens are often three-phase, so get a load calculation first.
- Compare ovens on heat-up energy, idle consumption and loaded cooking efficiency, not on the headline kW rating.
- Plan the swap around your trading pattern, and have the old unit’s removal arranged before the new one arrives.
Table of Contents
- Repair or replace: how to decide
- Check the site before you choose the oven
- Gas or electric: what changes at replacement
- Who is allowed to fit it
- Choosing the replacement: compare the right numbers
- A changeover plan that protects service
- Paying for it
- Our view: the oven is the easy part
- Find the right replacement with us
- FAQ
- Sources
Repair or replace: how to decide
No single age fixes the decision. Industry guidance from engineers suggests well-maintained combi and convection ovens often run for 10 to 15 years, but that depends heavily on descaling, door seals and water quality, so treat it as a rough guide.
Replacement usually makes sense when:
- repairs are recurring and the same fault keeps returning, such as failed elements, fans or door seals;
- the oven no longer holds temperature evenly, so product quality varies between trays or racks;
- parts are hard to source for an older model;
- your menu or volume has changed and the oven is now too small, too slow or the wrong type;
- the unit is gas-fired and an engineer has flagged safety concerns you cannot resolve economically.
Repair usually makes sense when the fault is a single, inexpensive part on an otherwise sound oven that still suits your output. Ask your engineer for a written note of what failed, what it cost and what else is close to failing. That note is useful whichever way you go.
A safety fault on a gas appliance is not a repair-or-replace question to settle on cost alone. If you smell gas or suspect carbon monoxide, stop using the appliance, turn off the gas supply and call the National Gas Emergency Number on 0800 111 999.
Check the site before you choose the oven
The most expensive mistakes happen because the new oven was chosen first and the kitchen checked second. Work through this list with whoever will install it.
Fuel and input rating
Do not assume that the old oven’s connection proves the new one is compatible. A newer model may draw more power, or a gas model may have a different input rating or burner arrangement. Write down the new oven’s fuel, kW rating and connection type, and compare them with what is actually available at the wall.
A frequent hidden failure is finding that a new electric oven exceeds the site’s available supply or needs three-phase power. The same guide lists a 6 to 20 tray combi oven at 10 to 30 kW on three-phase, usually the largest single load in a kitchen and one that needs its own circuit with an adjacent isolator. Ask a qualified electrician for a load calculation before you pick a model. Our own guides to commercial oven power requirements and how power affects the fit in a UK kitchen walk through single-phase and three-phase decisions in more detail.
Dimensions, clearances and access
Measure the footprint, but also the route in. Doors, corridors, lifts and tight turns decide whether a floor-standing combi arrives in one piece. Check clearances at the sides and rear for service access and heat, and the height above for any canopy or shelving. Our commercial oven placement guide covers positioning in more depth, and three site checks for catering oven fit is a quick companion read.
Water, drainage and cleaning
Combi ovens need a water supply and a drain, and often water treatment where the water is hard. Confirm where the supply and waste will run, and whether the new unit needs different connections from the old one. If you are moving from a convection oven to a combi, this is the item most often missed.
Ventilation and extraction
This is the part that surprises people. The HSE says ventilation is part of safe cooking performance, not only staff comfort. Its guidance on ventilation in catering kitchens says kitchens must remove fumes and heat, supply combustion air for fired appliances and prevent carbon monoxide building up. It also says the ventilation design must account for the cooking load, number of appliances, layout, staffing and cleanability.
For a replacement, that means:
- ask for the existing canopy and extraction design records, not only a visual inspection;
- confirm the system still suits the new oven’s load;
- for gas, confirm the interlock that links extraction to the gas supply is present and working.
On that last point, HSE guidance on gas safety in catering states that failure of mechanical ventilation should shut off the gas and that manual bypasses are not permitted. Never accept a workaround. If you are weighing a ventless hood against full extraction for a combi oven, read our guide on combi oven ventilation, and for the rules themselves see UK oven ventilation rules and compliance steps. The exact extraction design depends on your premises, so it needs a competent ventilation or gas engineer to sign it off.
Gas or electric: what changes at replacement
| Question | Gas-fired oven | Electric oven |
|---|---|---|
| Who fits it | Gas Safe registered engineer with the right appliance competency | Qualified electrician, plus a gas-free kitchen survey if converting |
| Biggest hidden risk | Ventilation and gas interlock not suited to the new unit | Supply capacity, phases and circuit protection |
| What to ask for | Commissioning record, interlock test, extraction design details | Load calculation, isolator location, circuit rating |
| Standard to mention | BS 6173 for gas catering appliances | Manufacturer’s electrical specification |
| Moving between fuels | Needs a gas and ventilation review | Needs an electrical review |
Switching fuel is the largest change you can make in a replacement. Moving from gas to electric removes combustion air and interlock questions but can raise the electrical demand sharply. Moving from electric to gas does the reverse. Either way, survey first.
Who is allowed to fit it
For gas, the rule is clear. HSE guidance for catering says replacement gas-appliance work in restaurants, takeaways, hotels and mobile catering must be done by a competent, Gas Safe registered person with the relevant appliance competency. Check the engineer’s current identity card and the appliance types listed on it before work begins. The HSE catering sheet on gas safety points to the Gas Safety (Installation and Use) Regulations for that competence requirement.
For installation practice, BS 6173 covers installing, servicing and maintaining gas-fired catering appliances, including new and previously used equipment. It is a good-practice standard rather than law by itself, so ask your installer which edition applies and how it applies to your premises and appliance.
Installers increasingly show their credentials online, and the way trades present qualifications and priority services on their sites is a useful prompt for what to ask for: registration numbers, appliance types covered and recent comparable jobs. Always verify the registration itself on the register, not just on a website.
Keep the commissioning and test records. HSE points out that these records matter as much as the physical connection, and you will want them for insurance and inspections.
Choosing the replacement: compare the right numbers
Two ovens with similar capacity can cost very different amounts to run. The UK government’s Energy Technology List treats heat-up time, heat-up energy, idle consumption, loaded convection consumption and cooking efficiency as separate measurements for convection ovens. To be eligible, an oven must be an electrically driven fan-assisted unit carrying a conformity-assessment mark, and the maximum idle-energy criteria are 1.35 kW for electric and 3.12 kW for gas.
For a buyer, that means asking suppliers for measured figures on all three: heat-up energy, idle draw and loaded efficiency. A headline power rating alone tells you very little about the bill. Our breakdown of commercial oven running costs in UK kitchens shows how those figures turn into a yearly total.
Match the oven type to what you actually bake and cook
- Bakeries: deck or convection ovens with even heat across trays matter most. Look at our bakery ovens.
- Cafes and sandwich bars: compact countertop convection or speed ovens keep the footprint small and service quick.
- Restaurants and caterers: combi ovens cover steaming, roasting and regenerating in one unit, and capacity planning is what stops installation delays. Our combi oven capacity guide helps you size one.
- Mixed menus: a convection oven plus a speed oven often outperforms one oven doing everything badly at peak.
If you are replacing like for like, resist the urge to simply buy the same model again. Check whether your volumes, menu and energy costs justify a different size or type.
A changeover plan that protects service
- Survey (2 to 4 weeks ahead): engineer visits for gas, electrics, ventilation and access. Ask for written findings.
- Specify and order: confirm model, fuel, connections and any accessories such as stands, grids, trays and installation kits.
- Arrange removal: decide how the old oven leaves. Some units can be sold for parts or scrapped; either way agree a collection date.
- Isolate and disconnect: done by the qualified engineer, not by kitchen staff.
- Position and connect: check levels, clearances and connections to the manufacturer’s instructions.
- Commission and test: safety checks, ventilation interlock test for gas, and a first-use run to confirm temperatures.
- Train the team: programmes, cleaning cycles and descaling routines.
Schedule the work for your quietest day. If you cannot shut, plan a temporary menu, or borrow oven capacity from a neighbouring site. A wider checklist is in our day one restaurant equipment checklist.
Paying for it
A replacement oven is a lumpy cost, and it rarely arrives at a convenient time. Spreading the payment can protect cash flow while the new oven starts earning. We offer flexible payment through iwocaPay and lease finance options, and our restaurant equipment financing guide explains how the main routes compare. Check the terms carefully, and talk to your accountant about how it fits your finances.
Our view: the oven is the easy part
We sell ovens, so you might expect us to say pick the best oven and everything else follows. In practice the reverse is true. When a replacement goes wrong, it is rarely because the oven was bad. It is because the supply could not carry it, the extraction was never checked, or nobody confirmed the door would clear the corridor.
Our advice is to start with your kitchen and your menu, then choose the oven. Bring us the make and model of the unit you are replacing, the fuel, the supply you have and what you cook at peak. We will help you narrow the range from Rational, Unox and Merrychef to the units that fit, and we can point you to installation support so the connection is made properly. If a like-for-like swap is wrong for you, we would rather say so before you order.
— Simon
Find the right replacement with us
If you are ready to compare, start with our commercial ovens range, or go straight to convection ovens for the most common like-for-like swaps. If you want a second opinion on fit, power or extraction, speak to our team via the store about expert advice and installation service before you order.
FAQ
Can I fit a commercial oven myself?
Not if it is gas. Gas catering appliances must be fitted by a competent Gas Safe registered person with the right appliance competency. For electric ovens, larger units often need dedicated circuits and isolators, so use a qualified electrician.
Does a replacement oven need new ventilation?
It can. The extraction and make-up air must suit the new oven’s load, and gas appliances served by extraction need a working airflow-to-gas interlock. Ask for the existing design records and have a competent engineer confirm that the system still suits the new unit.
Will my current electricity supply handle a new oven?
Do not assume so. Large electric combi ovens are often three-phase and can be the biggest load in the kitchen. Get an electrician to calculate the site load before you choose a model.
Should I buy the same model again?
Only if it still suits your menu and volume. Compare candidates on heat-up energy, idle consumption and loaded efficiency, and check whether a different size or type would serve you better at peak.
Sources
- HSE Catering Information Sheet 23: Gas safety in catering and hospitality
- HSE Catering Information Sheet 10: Ventilation in catering kitchens
- BS 6173: installation and maintenance of gas-fired catering appliances
- Energy Technology List: convection ovens
- Elec-Mate: restaurant kitchen electrical cost UK 2026
- Cairn Catering Engineers: commercial kitchen equipment lifespan