Baxi Duo tec
A great choice for homeowners and installers

Company type: Manufacturer

HQ: Warwick, England

Founded: 1866

CEO: Karen Boswell

The Baxi Duo tec is one of Baxi’s best-selling boilers, and it’s easy to see why. Equipped with a wall mounting frame to make installation even easier, the Baxi Duo tec is a popular choice for boiler installers, and its hot water output and flow rate make it a good choice for homeowners too. Let's find out what else makes the Baxi Duo tec such a popular choice.

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What Baxi Duo tec combi boilers are available?


Baxi Duo tec combi

The Baxi Duo tec combination boiler runs off natural gas and comes in hot water outputs of 24kW, 28kW, 33kW, and 40kW

Hot water output, or boiler size, refers to how much power your boiler uses to heat the water for your home.

Baxi Duo tec combi LPG

The Baxi Duo tec LPG comes in a hot water output of 28kW and instead of using natural gas supplied by the gas mains, the Baxi Duo tec LPG uses Liquid Petroleum Gas as fuel.

This simply means that, rather than burning natural gas, the Baxi Duo tec burns liquid petroleum gas to produce the energy it needs to heat the water it uses when heating up your home.

Unlike natural gas, which is supplied from the mains gas network, liquid petroleum gas is stored in an external tank that is connected to the Baxi Duo tec combi LPG boiler.

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Baxi Duo tec key features

Great for rural properties

The Baxi Duo tec comes in an LPG version, which is a practical solution for rural properties that have limited or no direct access to the mains gas supply.

An estimated 4 million homes across the UK are not connected to the gas network, and many of them have relied on oil boilers to heat their homes.

A Baxi Duo tec LPG combi boiler is a cheaper and more environmentally friendly alternative to most oil boilers currently on the market today.

If you are one of the 4 million households that live off-grid, and you are considering an alternative to gas or oil boilers, why not check out our "Everything you need to know about electric boilers" blog to see if they are a better choice for your needs.

Exceptional flow rate on the 40kW model

Along with the Baxi Platinum 40kW combi boiler, the Baxi Duo tec 40kW has the highest flow rate of any Baxi combination boiler, with an impressive flow rate of 16.4 litres per minute. The flow rate refers to how much water can flow through the boiler and the speed at which it can come out of a tap or shower head.

A good flow for a shower is between 12-15 litres per minute, and the Baxi Duo tec 40kW model exceeds this, meaning that it will produce a strong flow of water even if more than one tap or shower is on at the same time.

Can be controlled with your smart device


Baxi Duo tec combi boilers are compatible with Baxi uSense. Baxi uSense is a Wi-Fi thermostat that can be controlled remotely by a smart device.

Features of Baxi uSense are:

  • More control - Schedule your heating to fit in with your lifestyle
  • More flexibility - Control you heating from your smartphone or tablet, anytime, anywhere so you never come home to a cold house again
  • More savings - Keep an eye on how much energy you're using, enjoy maximum efficiency and manage your bills

Built-in frost thermostat

The Baxi Duo tec is equipped with a built-in frost thermostat that helps prevent the water in your central system from freezing. Water in boilers installed in colder parts of properties, such as the garage or loft, is at risk of freezing if temperatures get low enough. If the water in your boiler freezes, then the boiler is likely to breakdown which could cost you hundreds in boiler repairs.

Thanks to its built-in frost thermostat, a Baxi Duo tec combi boiler will detect when the temperature has dropped to a dangerously low level. It will then ignite and send hot water around the central heating system until the risk of freezing has been avoided in order to prevent frost damage to the boiler and the central heating system.

Can be installed in places where some other boilers can’t

Thanks to its compatibility with Baxi’s Multifit flues, Baxi Duo tec boilers can be installed further from an outside wall, in places where other boilers might not be able to be installed.

A boiler flue is the outlet through which steam and toxic gases are safely expelled and Baxi’s Multifit flues are available in a variety of lengths, bends and accessories.

Being compatible with such a wide range of flues gives boiler installers more options when it comes to choosing a new location for your new Baxi Duo tec boiler.

Can operate at lower temperatures to save fuel and money

Baxi Duo tec boilers could save you fuel and money with their “weather compensation” feature. When used with a Baxi In Flue Outdoor Sensor, this weather compensation feature tells the boiler to adjust the temperature of the water it uses, based on the outside temperature.

A Baxi In Flue Outdoor Sensor, or IFOS, is an outdoor sensor that clips on to the flue and takes temperature readings from outside the house and feeds this information to the boiler in order to work out how much energy is needed to heat up the home. The boiler will then adjust its power output accordingly. For example, if the IFOS detects that it's warm outside, less heat will be needed to keep the rooms warm enough, so the boiler temperature will turn down.

Operating at a lower temperature makes the Baxi Duo tec more efficient, which saves fuel and reduces carbon emissions without compromising user comfort.

Easy and affordable way to be Boiler Plus compliant


Boiler Plus is a government legislation that aims to regulate and improve the way homes use energy by increasing the efficiency of their heating systems. Newly installed combination boilers require one of four measures to be fitted and installing a Baxi IFOS meets one of the requirements.

A Baxi IFOS can be purchased for around £30 and can be installed within minutes, making it an easy and affordable way to be Boiler Plus compliant!

Quick and easy installation

Baxi Duo tec combination boilers are supplied with a pre-plumbing jig for quicker and easier installation.

Baxi’s pre-plumbing jig is a wall-mounted frame that is pre-fitted with all the valves, fittings, gas taps, filling loop and connections needed to connect the Baxi Duo tec to the pipework. Once the pre-plumbing jig is properly fitted to the pipework, the boiler installer just needs to align the Baxi Duo tec with the pre-plumbing jig, secure all the connections and the flue, and the installation process is complete.

If you would like to find out more about Baxi filling loops and how they are used to repressurise your Baxi boiler, then click here.

Is the Baxi Duo tec suitable for my home?

The Baxi Duo tec comes in sizes ranging from 24kW-40kW, meaning there is a Baxi Duo tec model for most sized homes.

You can use this table as a rough guide to which Baxi Duo tec combi boiler is suitable for your home.

Property Type Suitable Baxi Duo tec combi boiler
  • 1-2 bedrooms
  • 1 bathroom
  • Fewer than 5 radiators
  • Baxi Duo tec 24
Small house
  • 1-2 bedrooms
  • 1 bathroom
  • 5-7 radiators
  • Baxi Duo tec 24
  • or
  • Baxi Duo tec 28/LPG
Medium house
  • 2-3 bedrooms
  • 1 bathroom
  • 6-7 radiators
  • Baxi Duo tec 33
Family house
  • 3-4 bedrooms
  • 1 bathroom
  • 1 ensuite
  • Up to 10 radiators
  • Baxi Duo tec 40
Large family house
  • 4-5 bedrooms
  • 2 bathroom
  • 1 ensuite
  • Up to 15 radiators
  • N/A

It is important to get the correct size boiler for your property to ensure your central heating system is able to provide sufficient heat and hot water for your home. If your boiler size is too small, then it will struggle to heat up your radiators and your hot water may not get as hot as it should, whereas if the boiler is oversized, it will generate more power than needed to heat up your home, which will result in higher energy bills!

We recommend that you get your home surveyed by a Gas Safe registered engineer who will assess your property and heating demands in order to choose the right boiler for you.

Does your home have high hot water demands?

Although Baxi Duo tec combi boilers come in a range of different power outputs to suit a number of different sized properties, they are not the best choice for larger properties with very high hot water demands. As with all combi boilers, Baxi Duo tec combi boilers heat water on demand, and if the demand is too high, the flow rate to each water outlet will be reduced considerably.

If you have high hot water demands, then a Baxi Heat only boiler may be a better choice for you as they store large amounts of hot water in a tank or cylinder for later use.

If you would like to have a new Baxi Duo tec combi boiler or any other boiler installed, click here for more information.

How big is the Baxi Duo tec combi boiler?

The Baxi Duo tec combi boiler measures up at 780mm high, 450mm wide, 345mm deep and weighs 36kg. Such dimensions mean that the Baxi Duo tec is not a compact boiler, meaning it can’t be installed in a standard kitchen cupboard like other Baxi combination boilers, such as the Baxi 800 range.

Although Baxi Duo tec combi boilers aren’t compact boilers, they can still be installed in all the usual places boilers are installed, such as the kitchen, utility room, bathroom, or other rooms without taking up too much space. And due to their built-in frost thermostat and IFOS compatibility, they can be installed in colder areas of the property, such as the garage or loft and further away from an outside wall.

How energy efficient are Baxi Duo tec combi boilers?


All Baxi Duo tec models have an ErP (Energy-related Products) rating of A. ErP ratings are part of an European Union directive that sets out to improve the performance standards of all products that consume energy, such as heating appliances like boilers, in order to reduce greenhouse gas emissions. Energy-related products are graded from A-G, with A-rated products being at least 90% efficient and G-rated products being below 70% efficient.

Having a highly efficient LPG boiler such as the Baxi Duo tec LPG means that properties in areas that don’t have access to the mains gas supply can also enjoy the benefits of having an environmentally friendly boiler, such as lowering their household’s carbon footprint and reducing their heating and hot water costs.

LPG is the cleanest fossil fuel available to off-grid properties and is 15-20% cleaner than oil, which has been a popular choice for rural property homeowners.

How long is the warranty period for Baxi Duo tec combi boilers?

The Baxi Duo tec combination boiler comes with a 1 year parts and labour warranty as standard, but can be extended to 7 years if you follow these three steps:

  1. Either you or the Baxi boiler installer must register your warranty with Baxi within 30 days of the boiler's installation.
  2. Make sure your Baxi boiler is installed by a Gas Safe registered engineer who must complete a benchmark commissioning checklist.
  3. You must service your boiler once a year and your boiler service must be carried out by a Gas Safe engineer in line with the manufacturer's instructions.

If you would like to know more about Baxi warranties, click here.

Looking for a similar Baxi combi but with a longer warranty?

If you like all the features of the Baxi Duo tec but you are looking for a combi boiler with a longer warranty, then why not take a look at the Baxi Platinum combi boiler? It is Baxi's top-of-the-range boiler, and it comes with a 10 year extended warranty, which is the longest warranty duration that Baxi offers.

Give your boiler a service.

Make sure you don't invalidate your warranty. Call Smart Plan to get a boiler checkup to see if everything is in good working order.

OR 020 8146 3960

Baxi Duo tec Specifications

24 kW 28 kW/LPG 33 kW 40 kW
Width 450mm 450mm 450mm 450mm
Height 780mm 780mm 780mm 780mm
Depth 345mm 345mm 345mm 345mm
Weight 40.2kg 40.2kg 41.7kg 42.2kg
Fuel Type Gas> Gas/LPG Gas Gas
Energy Rating (Heating) A A A A
Energy Rating (Water) A A A A
Boiler Plus ErP 92% 92% 92% 92%
Flow Rate 9.8 l/min 11.5 l/min 13.5 l/min 16.4 l/min
Central Heating Max. Output 20 kW 24 kW 28 kW 32 kW
Hot Water Max Output 24 kW 28 kW 33 kW 40 kW
Sound Power Level 50 dB 53 dB 52 dB 50 dB
Flue Outlet Position Top Flue Outlet Top Flue Outlet Top Flue Outlet Top Flue Outlet
Warranty 7 years 7 years 7 years 7 years

Still need help with your Baxi boiler?

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