Double Ovens Explained: Built-In vs Built-Under, and Are Both Ovens Fan Assisted?

A double oven gives you two separate cavities in one appliance: usually a smaller top oven that doubles as a grill, and a larger main oven underneath. It is the classic choice for households that cook a roast and its sides at different temperatures, bake while grilling, or simply want a second oven for busy weekends. Before you choose one, there are three questions worth answering: should it be built-in or built-under, are both ovens fan assisted, and what electrical supply will it need? This guide walks through each.

Built-in vs built-under: what is the difference?

The two terms describe where the oven is installed, not how good it is.

• Built-in double ovens are designed for a tall housing unit, so the oven sits at chest or eye level. They are taller than built-under models, which usually leaves room for a larger main oven, and you do not have to bend down to check on food or lift heavy dishes. The trade-off is that you need a tall oven housing in your kitchen layout.
• Built-under double ovens fit into a base unit beneath the worktop. They suit kitchens without a tall housing, or layouts where the hob sits directly above the oven. Because the overall height is limited by the worktop, the two cavities are usually smaller than on a built-in model.

You can see the difference in practice with CDA's double ovens. The CDA DC941SS built-in double oven (also available as the DC941BL in black) lists a 35 litre top oven and a 59 litre main oven. The CDA DC741BL built-under double oven keeps the same 35 litre top oven but has a 50 litre main oven, because it has to fit beneath the worktop.

Which one should you choose?

• Choose built-in if you have, or are planning, a tall housing unit, you want the largest main oven, or you would rather not bend down to the oven every day.
• Choose built-under if your kitchen has no tall housing, you are replacing an existing built-under oven, or you want the oven directly beneath the hob to keep the cooking zone compact.

Whichever you pick, measure the existing aperture (height, width and depth) and compare it with the manufacturer's installation dimensions before you order. Built-in and built-under ovens are not interchangeable, and the two types need different housings.

Are both ovens fan assisted?

This is one of the most common questions about double ovens, and the answer is: not always. There are two broad layouts.

Fan main oven with a conventional top oven

This is the most common arrangement. The larger main oven has a fan, which circulates heat so you can cook on several shelves at once with fairly even results. The smaller top oven is a conventional (non-fan) oven, heated by elements, and it also contains the grill. The CDA models above follow this layout: their function lists show conventional oven, warming oven and electric grill in the top oven, and fan oven and defrost in the main oven.

A conventional top oven is not a weakness. Conventional heat is often preferred for some baking, it is useful for keeping plates and food warm, and it means the grill and a second oven are always available alongside the fan oven.

Twin fan (fan in both cavities)

Some double ovens are described as twin fan or double fan, meaning both cavities have a fan. This suits people who want to batch bake or cook two fan-oven recipes at once, without adjusting the recipe for conventional heat. If this matters to you, read the function list for each cavity on the product page rather than relying on the headline: a product called a "fan oven" may only have the fan in the main cavity.

Quick checklist when reading a spec sheet

• Top oven functions: look for "fan" or "fan oven". If you only see conventional, grill and warming, the top oven has no fan.
• Main oven functions: almost always includes a fan setting; multifunction models add extra modes.
• Capacities: check the net (usable) capacity of each cavity, not just the total.
• Cleaning: enamel, catalytic and pyrolytic interiors differ in how much scrubbing you will do. The CDA models listed here have an easy clean enamel interior.

What electrical supply does a double oven need?

Double ovens draw more power than most single ovens, so they are normally hard-wired rather than plugged into a 13 amp socket. The CDA DC941SS, DC941BL and DC741BL, for example, list a rated electrical power of 4.3 kW, a 20 amp power supply and no mains cable, which means they are designed to be connected to a suitable fixed supply rather than a plug.

In practical terms:

• Check whether your kitchen already has a dedicated cooker circuit and switch, and what it is rated for.
• Compare that with the oven's stated power rating and supply requirement in the installation instructions.
• If you are installing a hob on the same circuit, the combined load needs to be considered too.
• Have the connection made by a qualified electrician. Work on fixed wiring in a kitchen should not be treated as a DIY job.

If you are replacing an older double oven like for like, the existing supply may well be suitable, but it is still worth having it checked rather than assuming.

Other things to check before you buy

• Housing and ventilation: follow the manufacturer's guidance on cabinet construction and ventilation gaps. Built-under ovens in particular sit close to the worktop and hob.
• Door style: most double ovens have drop-down doors. If you specifically want a door that opens to the side, look at single ovens instead; our side opening ovens guide explains who they suit.
• Do you need a double oven at all? If your second oven would mostly be used for reheating or quick meals, a single oven paired with a built-in combination microwave oven can give you two cavities with microwave speed as well.
• Is it time to replace? If your current oven is struggling, our guide to when to replace an oven covers the warning signs.

Summary

• Built-in double ovens go in a tall housing at eye level and usually offer the bigger main oven.
• Built-under double ovens fit beneath the worktop, with smaller cavities to suit.
• Many double ovens have a fan main oven and a conventional top oven with grill; twin fan models have a fan in both, so check each cavity's functions.
• Most double ovens are hard-wired to a dedicated supply, so check the power rating and use a qualified electrician.

Browse our double ovens and built-under ovens, or contact the team if you would like help checking a model against your kitchen before you buy.