Reconditioned Rational Combi Ovens

Servall stock the largest range of Used Rational Ovens in  Ireland

In Stock Now

Used Rational Combi Master Plus (CMP)  6 & 10 Grid models available

In Stock Now

Used Rational Combi Master (CM) 6 & 10 Grid models available

Reconditioned Rational Combi Ovens

Fully Tested Used Rationals sold with warranty

Installation Available

Servall offer a full installation service ask our team

  Frequently Asked Questions

What is a Rational Oven ?

Rational AG is a German manufacturer of combi steamers and commercial ovens, commonly called a Rational Combi by chefs the world over.  Learn more about the functionailty and efficiency of a Rational oven in our information below

Rational pioneered the idea of combining steam and convection cooking into a single appliance and have since been constantly working on continuously improving it. Rational combi ovens have become an integral part of commercial kitchens.

Often described as the backbone of a commercial kitchen, a Rational Combi oven is always top of any Chefs list when choosing quality equipment for a new commercial kitchen.

Servall sell quality used Rational ovens; these ovens come fully reconditioned, tested by our in house engineers and cleaned to an incredibly high standard. A Used Rational Combi Oven from is a cost efficient way to bring quality reliability and efficiency into your commercial kitchen.


What does a Rational Combi Oven do?

A Rational combi oven is a commercial oven with three functions: convection, steam and combination cooking.

The benefits of a Combi oven

In the convection mode, the oven circulates dry heat – ideal for pastries and breads and so it is popular with chefs who do their own baking.

When used in the steam mode the Rational oven injects water into the oven to poach fish, rice and vegetables.

The real benefit of a Rational oven to a Chef is when it combines these cooking functions; convection and steam, giving you more control of the moisture levels in food.

When the combi oven is used in the combination mode it uses both dry heat and steam to maintain exact humidity levels. These levels are adjustable from 0% to 100% of possible maximum relative humidity.

How does it work?

A Combi oven  controls the humidity inside its chamber, maintaining exactly the desired atmosphere, reducing shrinkage and weight loss while also improving cook times and results

By controlling humidity inside a combi oven, it enables the Chef to cook food with higher heat and moisture control capabilities.

At one hundred percent relative humidity, you will be able to cook with high heat without burning or excessively drying out food products such as roast turkey, roast beef and fish. 

For this reason many hoteliers and restaurateurs’ who serve large numbers of guests purchase a combi oven. A combi oven is also of benefit to our customers operating successful Deli’s or Take Away premises who prepare carvery dinners for the food to go market.

Do I need a Rational Combi Oven?

We recommend a reconditioned Rational combi oven to business owners and chefs, currenlty running a high output kitchen, who want to firther increase cooking capacity within a small footprint. The reason we make this recommendation is because a combi oven can perform a number of cooking functions removing the need for a lot of expensive equipment.

How can a combi oven help my business?

A combi oven can help you:

  • Reduce Shrinkage
  • Save Time and Labour
  • Eliminate Flavour Transfer (when multiple food items are cooked at the same time)
  • Deliver Consistent Cooking Results
  • Create New Dishes – Sous Vide
  • Cook different menu items on each rack
  • Become Energy Efficient

What about energy efficiency?

Save money on your electric and water bills with the combi oven, which features reduced energy use, minimum water consumption and super insulation preventing heat loss.

Independent advice

Servall have supplied Used Rational combi ovens to many of our customers in a wide variety of establishments from Convenience store Delis to award winning hotels and restaurants.  If you think that you might benefit from adding a combi oven to your commercial kitchen contact us for more information.

Servall are an independent supplier of catering equipment and pride ourselves on providing impartial advice.

How to install a Rational Oven?

A Rational  oven can only be installed by a qualified catering engineer.  A Combi oven is an investment and a real asset to any commercial kitchen, it will become the work horse in your business and requires more than just unboxing and wiring in. It will work best when delivered, installed and commissioned by a suitably qualified catering engineer.

Heavy Lifting

The oven itself is extremely heavy and should only be handled by experienced professionals.

Specialist install

To install a Rational Combi oven you will need

  • Power supply 3 phase electricity or Gas
  • Water supply for the Steam and Cleaning function
  • Waste pipe for drainage
  • A stainless steel equipment stand or custom built table with runners

The drainage will need to be set up correctly and often custom fitted to work best in each kitchen.


Once installed the equipment will require its parameters set and tested  to ensure that everything is working as it should.

Training & Maintenance

Then the final step is staff training. It is important that all of your team understand the benefits of the new equipment. Training will explain how the various cooking functions work and help ease any staff concerns about using a new oven. Also instruction will be required on daily cleaning and light maintenance which will help keep the oven performing at its best.

Book an engineer

Servall hold the largest stock of used Rational combi ovens in Ireland and can offer a full installation service. Same Day delivery and installation can be arranged if you have had a disruption to your service because of a critical equipment breakdown.  Contact us to check availabiliy of our installation engineer.

Our delivery and installation  options are;

  • Purchase only pallet delivery direct to your door lead time 1-2 days
  • Servall team delivery without installation lead time 1-2 days
  • Servall team delivery with full installation lead time 1-2 days
  • Servall team delivery with full installation and customer training lead time 1-2 days

What size of combi oven do I need?

Do you need 6, 10 or 20 grid capacity combi oven?

Servall offers multiple sizes of Used Rationals for all kitchens. Our customers have installed them in Cafes, Bistros, Wedding Venues and restaurants of differing sizes.

For smaller cafes and bakery shops a 6 grid combi oven is perfect – ideal for pastries and breads. It is popular with chefs who want to move from traditional convection cooking. The 6 Grid combi offers these additional functions and is still small enough to fit in a compact commercial kitchen. It is also very easy to use and easy to clean.

The benefit of going for the larger 10 grid size is the extra capacity within the oven for the same footprint as the smaller 6 grid oven. Many of our restaurant customers and hoteliers would use this size of oven; it enables chefs to cook multiple food items  at the same time for example, steamed vegetables and roasted meat joints.

Some customers choose to buy two 6 Grid ovens which can be stacked one on to of the other. The reason we recommend this for some customers is to; create more flexibility, save energy and save money !!

Many restaurants are very busy on Friday, Saturday and Sunday but service is calmer midweek. When service is quiet chefs can choose to run one oven and then during peak times, when catering for  larger weddings or events for example, or over a busy weekend, the chef can increase capacity by using the second oven.

This flexibility in capacity takes the pressure off, allowing the service to run efficiently with the addition of the second oven, cooking on a full 12 grid capacity.  Having a second oven also protects the chef against possible breakdowns providing extra piece of mind and minimising business interuption. 

What size of combi oven do I need?

Call our team to discuss what size of combi oven you need for your menu and seating capacity.Servall pride themselves in making a recommendation based only on our customers’ needs. If you think that you might benefit from adding a combi oven to your commercial kitchen contact us for more information.


How to clean a Rational Oven?

It is really easy to clean the Rational combi oven

To clean the rational oven one button activates the self cleaning mode on the  Rational SCC range of combi ovens. The Combi Master and Combi Master Plus models also have a simple cleaning process which is easy to follow; the steps are on an infographic inside the oven.

Regular cleaning and in house maintenance will keep your combi oven in great condition and extend the lifespan of the oven.

A combi oven does require professional cleaning and descaling from time to time dependant on usage and the water hardness  in the area.

Book an Engineer

It is recommended that a full maintenance on the oven be completed once a year. Descaling is also required regularly; a suggested schedule is outlined in the operating manual.

Servall have a team of trained engineers to support our customers contact us to book an engineer

How to descale a Rational Oven?

To maintain your Rational combi oven in good working order it will need descaled as well as regularly cleaned

The steam generator in your appliance requires regular descaling, depending on water hardness and use.
We recommend the following descaling intervals, based on 8 hours steaming per day:

  • Medium use at least 1 x annually
  • Frequent use at least 2 x annually
  • Heavy use at least 3 x  annually

These recommended descaling intervals may vary from the approximate values given above, depending on the composition of the water in your area (e.g. minerals).

Book an Engineer

Book an engineer to complete the descaling process. This will minimise downtime and reduce the risk of damage to the oven. For guidance refer to the operating manual, a suggested schedule is outlined within.

Contact us to book an engineer

How to program Rational Oven?

To program a Rational Combi oven you need a competent catering technician with expertise in programming Rational Ovens.

This should not to be undertaken by a member of staff unless they have received specific training.

Remember this oven is the heart of your kitchen and you do not want to cause any damage to parts or components and most of all your self.

We would recommend contacting your local qulaified service engineer

Don't Be Shy

If we didn’t answer all of your questions, feel free to drop us a line anytime.

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