Does a commercial oven require a drain?

Not all commercial ovens need to be connected to a drain. A standard convection oven or bake-off oven can often be installed without a drain, whereas a combi oven generally requires one.

The deciding factor is therefore which type of oven you have – and not just whether the oven can add steam or moisture.

A combi oven must have a drain

When installing a combi oven, you should expect to have a drain installed.

During operation, condensation and liquid form inside the oven, and if the oven has an automatic cleaning cycle, the wash water must also be drained away. Depending on what is being cooked, grease and food residues may also pass through the drain.

An oven with automatic cleaning must therefore always have a functional drainage installation.

An oven with steam does not always require a drain

It is worth distinguishing between a combi oven and a convection oven with moisture injection capabilities.

A bake-off oven such as the UNOX BAKERLUX SHOP.Pro may have moisture injection without necessarily needing to be installed with a drain.

Therefore, you cannot simply look at whether the product description says "steam" or "moisture." Check the installation requirements for the specific oven.

Does the oven have a condensing hood?

If a condensing hood – also called a steam condenser – is mounted on top of the oven, you typically also need to account for a drain. The hood collects steam from the oven and condenses it into water. Waterless hoods do not require a drain.

This means that an oven that can normally be installed without a drain may in some cases still require one when a condensing hood is installed. Therefore, always check the installation requirements for both the oven and the specific hood.

How is the drain established?

On the UNOX combi ovens that we typically install, the drain outlet is Ø30 mm. From there, we typically run the piping in approximately Ø32–40 mm.

The drain pipe should be at least 30 cm long and installed with a minimum slope of 4% so that water and residue can drain away from the oven.

This also means that the location of the fixed drain must match the height of the oven's drain outlet. A wall drain that sits too high can therefore cause problems.

Floor or wall drain?

Both can work. It depends primarily on how high the oven's drain outlet is located.

A standard tabletop model on a stand can often be connected to a wall drain. If the oven stands very low, a floor drain may be necessary.

This applies, for example, to large floor models and some installations with two ovens stacked on top of each other, where the drain outlet can be located close to the floor.

Avoid too much distance to the drain

As a rule of thumb, we try to keep the drainage run relatively short.

If you go significantly beyond about one meter from the oven to the fixed drain, the risk of problems increases – especially if the oven is used for fatty products.

Fat can cool down and solidify in the pipe and eventually cause accumulations or blockages.

If the oven is primarily used for products with very little fat, the distance is less critical. However, if the drain can be placed close to the oven, that is usually the best solution.

Remember the trap

The drainage installation must also be carried out correctly with a water trap. When we supply a UNOX combi oven, we normally include a water trap with the oven, unless the customer specifically declines it.

It is important to plan the drain before delivery so that the oven, water trap, and fixed installation can be connected correctly.

What if you have two ovens?

With two combi ovens stacked on top of each other, the drains are usually joined together.

Here you must think not only about the piping, but also about how much water the fixed drain must be able to handle. In some installations with two ovens, about 40–60 liters of water can be discharged during a cleaning cycle over approximately one and a half hours.

This should therefore be considered when dimensioning the plumbing installation.

The most common mistakes

Most professional kitchens already have good options for drainage, but we see two problems in particular with new installations:

• The drain is located too high in relation to the oven's drain outlet.
• The drain is too far from the oven, making the pipe run unnecessarily long.

It is therefore a good idea to choose the specific oven before the fixed installations are established. Then the plumber can place the drain based on the actual dimensions of the oven instead of guessing.

In short

Combi oven: Yes, expect to need a drain.

Oven with automatic cleaning: Yes, it must have a drain.

Standard convection oven: Typically no.

Bake-off oven with moisture injection: Not necessarily. Check the specific model.

If you are planning a new kitchen, you can also read our guide to installing a commercial oven or see our selection of commercial ovens.