Venting Hob Installation Info – Everything You Need To Know
Venting hobs are definitely on the rise. From when I was first introduced to them several years ago to now, the number of kitchen projects including them has shot up!
However, a venting hob can still cause some confusion and create a sense of mystery about how exactly they work and fit in with the rest of your kitchen design and installation.
In this post, I’ve tried to think of and answer all the little technical questions I get asked about venting hobs.
Let’s get into it!
What is a vented hob?
A quick reminder before we get into all the technical stuff!
A vented hob, sometimes referred to as a downdraft cooktop, hob with a built-in extractor or an extractor hob, is a cooking hob that incorporates an effective ventilation system within its structure. It’s essentially a two-in-one appliance. Hob and cooker hood.
The primary function of a vented hob is to eliminate the need for a separate overhead extraction hood by integrating the extraction fan directly into the hob. As soon as you start cooking, the vented hob springs into action, suctioning down the steam, smoke, and odours directly from your pots and pans.
Venting hobs are most commonly induction, however, they are available as ceramic (electric) and gas models as well.
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How do venting hobs work?
During operation, the hob uses gas or electricity (induction or ceramic) to heat the cookware. Simultaneously, the integrated extractor fan is activated to draw in the resulting steam, smoke, and odours.
In a ducted vented hob, the extracted air is directed through installed ductwork, venting it outside the building, thereby keeping the kitchen environment clean.
Alternatively, a vented hob with a recirculation mode routes the drawn air through internal filters, which trap grease and neutralize odours. The air is then released back into the kitchen.
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How Much Cabinet Space Does A Venting Hob Take Up?
Depending on the make and model venting hobs typically need between 200 – 300mm of depth from the top of your countertop down into the cabinet underneath.
In most cases, the hob will take up the space of the top drawer (if you’re having a drawer cabinet below) and may even start to reach the top of the middle drawer.
The amount of width space required will depend on the size of the cooktop. Most venting hobs are approximately between 60 – 90cm wide. However, the exact width will vary across makes and models.
Usually, the cooking surface is a little wider than the housing underneath. For instance, a 60cm wide model might be able to fit in a 50cm wide cabinet. Always double-check!
As well as the main body of the venting hob, which houses the motor, electronics and overflow chambers etc.. the other consideration to make is the positioning of your venting ductwork.
How does the ductwork for a vented hob get installed?
As you can see from the image below, the ducting needs to come out of the hob and go down into the plinth space underneath your kitchen cabinet. With some manufacturers and models, the ducting can be rotated to come out on different sides (left, right or back) to optimise the route out.
From there it will either go along to an outside wall where it will vent externally. Or it will vent back into the room (recirculating mode) through a grill or opening in the plinth/toe kick.
If the ducting is positioned to come out the back of the hob and down you will need additional space (or depth) behind your kitchen cabinet to accommodate the ducting. Typically 70cm depth is required.
This is usually achievable on kitchen islands where you may have a void between cabinets or end panels. If your hob is positioned in a cabinet against a wall, you will need to bring the cabinet off the wall to create this extra depth.
However, if the venting hob installation is on a run of cabinets against a wall and you cannot create this extra depth, or you have a shallow-depth island and don’t have that additional depth available, the ducting will have to come down inside the kitchen cabinet, taking up space internally.
This means that if you want any drawers inside, they will have to be shallow-depth drawers or the drawer box will need to be cut around the ducting.
So, in some instances, when installing an induction hob with a built-in extractor, you will not only lose the top drawer but you’ll also lose the full depth of any other drawers underneath.
It all depends on the make, model and ducting positioning, as well as the location within your kitchen layout.
For more information about different ducting options check out this PDF from Bosch.
Can You Have Drawers Under A Venting Hob?
Yes, you can have drawers underneath a venting hob. The exact amount and configuration of drawers will depend on the model of the venting hob as well as the positioning of the ducting.
Usually, you will lose the top drawer of any drawer cabinet because the induction hobs motor, fan and electronics take up this space. However, there is normally enough space to have the bottom two deep pan drawers underneath.
Always check the installation specification to see exactly how much space the appliance needs.
Can You Fit A Venting Hob Above An Oven?
No. You won’t be able to install a venting hob above a full-size built-under oven. Because of the venting hobs fan, motor and electronics it means it takes up too much space underneath your countertop and inside your base cabinet. Therefore you won’t have enough room to install a full-size oven underneath and inside a base cabinet.
However, depending on the model of the venting hob and how much space (depth) it takes up, you might be able to install a compact oven (45cm high) underneath one. With the extra gap at the top of the base cabinet for the venting hob to fit in.
Can venting hobs be installed in Kitchen islands or peninsulas?
Yes, venting hobs can indeed be installed in kitchen islands or peninsulas, and in fact, they are an increasingly popular choice for such setups. The installation, however, does come with its own set of considerations and challenges.
The first step is careful planning. The location of the hob needs to be determined, considering factors such as proximity to an electrical supply and ease of access. The venting system also needs to be planned, deciding whether it will vent outside or use a recirculation system.
For hobs that vent externally, the ductwork has to be installed under the floor or within the island structure itself, leading to an exterior wall. This can be complex, as it requires creating a pathway that does not interfere with the kitchen’s structure or aesthetics. It also requires carefully sealing the ducts to ensure efficiency.
For hobs with a recirculation mode, the carbon/charcoal filters need to be installed and accessed within the island or peninsula. It’s important that these are easily accessible for regular maintenance and replacement.
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Where does the steam go in a venting hob?
Venting hobs operate with an integrated extractor fan which is activated during cooking. This fan functions as a vacuum, drawing in the smoke, steam, and odours that arise from the cooking process.
This extracted air is then directed via ductwork installed within or under the hob, typically leading outside the building, effectively removing the cooking byproducts from your kitchen.
In situations where outside venting isn’t possible, vented hobs can function in a recirculation mode. Here, the extracted air is filtered to trap grease and neutralize odours before it’s recirculated back into the kitchen.
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Venting Hob Power Requirements (UK)
When planning to install a vented hob (or any induction hob or oven for that matter) in your kitchen, it’s crucial to consider the power requirements.
The power requirements will vary depending on the size and model of the hob. However, as a rule of thumb, most vented hobs in the UK require a dedicated electrical circuit with a power rating of around 30 to 45 amps.
It’s essential to check the specific power needs stated in the manufacturer’s manual for the particular model you’re planning to install.
Building Codes and Regulations for Vented Hob Installation (UK)
When installing a vented hob in the UK, it’s crucial to be aware of and comply with relevant building codes and regulations. These rules are in place to ensure the safety and efficiency of your installation.
One of the main regulations to consider is the UK’s Electrical Safety Standards. These standards mandate that any electrical installation work, including the installation of a vented hob, should be carried out by a competent person, ideally, an electrician registered with an approved scheme like the NICEIC or ELECSA.
When it comes to ductwork, you’ll need to ensure the ducts are installed in a way that complies with the UK’s building regulations, specifically Part F (Ventilation). The guidelines stipulate how the ductwork should be installed for proper ventilation.
If you’re installing a vented hob with a recirculation mode, you may need additional ventilation elsewhere in the room.
You will also need to take into account that the carbon filters used in recirculating models need to be changed regularly, and you’ll need to follow the manufacturer’s guidelines to ensure they’re installed and maintained correctly.
There you have it! All the venting hob installation information you’ll need…I hope!
With careful planning and installation, you can integrate a venting hob into your kitchen, reaping the benefits of efficient cooking and extraction in one streamlined appliance.
So, if you’re planning a kitchen renovation or simply considering an upgrade to your existing cooktop, the vented hob certainly merits consideration for its blend of functionality and contemporary design.
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Michael is a kitchen designer from the UK. He's been designing and project managing new kitchen installations for over 10 years. Before that, he was an electrician and part of a team that fitted kitchens. He created Kitchinsider in early 2019 to help give people advice when it comes to getting a new kitchen.