A combi oven is a significant investment — and like any professional kitchen equipment, it rewards the operators who look after it. A well-maintained unit will deliver consistent results service after service, hold its value if you ever come to upgrade, and avoid the unplanned downtime that hits hardest in the middle of a busy week. Neglect the basics, and even the best oven on the market will start costing you more than it should — in call-out fees, replacement parts, and lost production.
At CaterCombi, we've spent years refurbishing, servicing, and supplying combi ovens across the UK. We see first-hand what separates the units that last from the ones that don't — and in the vast majority of cases, it comes down to how they're looked after day to day. The good news is that most of it is straightforward. You don't need specialist knowledge or extra equipment. You just need the right habits built into your daily and weekly routine.
Here are CaterCombi's top tips for keeping your combi oven running at its best.
1. Place a drip tray at the bottom of the oven
One of the simplest and most effective habits you can build is placing a tray at the base of the oven cavity during cooking. This catches drippings, food debris, and residue before it reaches the bottom and blocks the drain nozzle. A blocked nozzle is a common cause of drainage issues and unpleasant odours. A quick tray swap at the end of service costs seconds and can save a costly call-out.
2. Leave the door open overnight
After the final clean of the day, leave the oven door ajar overnight. This allows the cavity to fully ventilate and dry out, preventing moisture from sitting against the door seal. Over time, a gasket that's repeatedly left in a damp, closed environment will degrade faster — cracking or losing its seal — which leads to steam loss during cooking and eventually a replacement job. Leaving the door open costs nothing and takes a second. It's a small habit that meaningfully extends gasket life and keeps the cavity fresher between services.
3. Don't overload the oven
It's a tempting shortcut during a busy service, but overloading the oven works against you. Combi ovens rely on consistent airflow around each tray to deliver even heat and steam distribution. Pack the cavity too tightly and you create dead zones where air and steam can't circulate properly — resulting in uneven cooking, longer cycle times, and food that needs finishing elsewhere. As a rule, leave adequate space between trays and avoid using every runner if the load doesn't require it. You'll get better results, more consistent cooking, and less strain on the fan motor over time..
4. Check clearance around the unit
Where you position a combi oven matters as much as how you use it. Placing it too close to a fryer, range, or other high-heat equipment exposes the control panel and electrical components to sustained radiant heat — something they're not designed to handle continuously. Beyond heat, a nearby fryer presents a grease ingress risk: airborne grease particles can work their way into the control compartment and cause faults that are both difficult to diagnose and expensive to fix. Allow a minimum of 18 inches of clearance on the sides where possible, and ensure there's adequate access to the rear for servicing. It's also worth checking that ventilation slots aren't facing a direct heat source, as restricted or hot intake air affects the electronics and shortens component life.
5. Door misalignment tip
If you're getting steam escaping from a corner of the door, the instinct is usually to replace the gasket — but it's worth ruling out door misalignment first. A door that has dropped slightly over time, through repeated use or a knock during service, can create a gap at one corner even when the gasket itself is in perfectly good condition. Before calling out an engineer, check whether the door sits evenly across its full height when closed. If it doesn't, unhinged and carefully realigning it has resolved the issue entirely in many cases we've seen. It costs nothing to check and could save you an unnecessary parts and labour bill.
6. Don't mix cleaning and sanitising chemicals
Combi oven cleaning systems use two separate chemicals for a reason — the cleaner and the sanitiser work in sequence and are not designed to be combined. Mixing them can neutralise the effectiveness of both, damage internal components, and in some cases create a hazardous reaction. Always use the correct chemical at the correct stage of the cleaning programme, and make sure you're using products approved for your specific oven model — off-brand alternatives can void warranties and cause long-term damage to the cavity lining and seals. It's also worth keeping adequate stock on hand. Running out mid-programme and leaving a half-cleaned oven overnight is a hygiene risk and can leave chemical residue in the system. Check stock at the start of each week, not at the end of service when it's too late.
7. Descale regularly — especially in hard water areas
Limescale build-up is one of the most damaging and overlooked causes of combi oven deterioration. The steam generator, probes, and internal pipework are all vulnerable, and in hard water areas like Kent, scale can accumulate quickly. Skipping it leads to reduced steam performance, inaccurate temperature readings from scaled probes, and in serious cases, premature failure of the steam generator — one of the most expensive components to replace. If your oven has an automatic descale programme, use it on schedule. If not, a manual descale with the correct approved chemistry is straightforward and well worth building into your weekly routine. A water softener fitted to the inlet supply is worth considering for high-volume sites.
8. Keep the control panel and vents free of grease
The control panel and ventilation slots are easy to overlook during the end-of-service clean, but grease and moisture ingress are common causes of electrical faults and display failures. Wipe down the panel with a damp cloth — never spray chemicals directly onto it and check that the ventilation slots on the sides or rear aren't blocked by cloths, trays, or adjacent equipment. A blocked vent causes the electronics to run hot, which shortens component life significantly.
9. Run the self-clean programme at the right level for what you've cooked
Most modern combi ovens offer multiple cleaning levels — light, medium, and heavy — and it's tempting to default to the quickest option at the end of a long service. But running an underpowered clean after a heavy roasting session leaves grease residue that carbonises over time, making future cleaning harder and eventually affecting cooking performance and hygiene scores. Match the clean level to what the oven has actually done that day. It uses slightly more chemical and water, but it protects the cavity lining and keeps the oven performing consistently.
