Baxi 800 combi boiler review

Company type: Manufacturer

HQ: Warwick, England

Founded: 1866

CEO: Karen Boswell

The Baxi 800 combination boiler range comes with the maximum warranty length Baxi has to offer and includes a top-of-the-range magnetic system filter to protect the boiler and the central heating system. Read on to find out what other features come with Baxi 800 combi boilers and if there is one to suit your needs.

Baxi Logo

What Baxi 800 combi boilers are available?


The Baxi 800 combination boiler range is available in three different sizes:

  • Baxi 825 - 25kW
  • Baxi 830 - 30kW
  • Baxi 836 - 36kW

Boiler size (output)

In boiler talk, boiler “size” means the boiler’s power output. A boiler’s output is measured in kilowatts (kW). In simple terms, how much power does a boiler use to heat water and the central heating.

Generally speaking, the more heat and hot water a property needs, the higher the boiler’s power output needs to be.

Hot Water Output Central Heating Output
Baxi 825 25kW 20kW
Baxi 830 30kW 20kW
Baxi 836 36kW 25kW

Other than the different power outputs, the main difference between each Baxi 800 combi boiler is its flow rate.

Flow rate

Baxi 800 combi boilers are available with the following flow rates:

Baxi 825 10.2 litres per minute
Baxi 830 12.2 litres per minute
Baxi 836 15 litres per minute

A boiler’s flow rate refers to how much hot water the boiler can send to hot water taps or showerhead in one minute.

Typically speaking, the more hot water outlets in a property, the higher the boiler’s flow rate should be, especially if people within the property tend to use a few water outlets at the same time.

You can find out which Baxi 800 combi boiler is best suited for your needs further down in the article.

Call our free helpline.

For any questions that you have regarding your boiler, give our free helpline a call, Monday - Friday, 8am - 5pm. Let us do the hard work!

OR 020 8146 3960

Where can I install a Baxi 800 combi boiler?

Baxi 800 combi boilers can easily be installed in all the usual places you would store a boiler, such as in the kitchen, loft, airing cupboard, and so on, but due to their compact size, they can easily be installed in a standard kitchen cupboard, which could save you space, time, and money!

A key benefit of combination boilers is their small size in comparison to regular and system boilers, which require water tanks in order to operate.

Baxi 800 boilers are 700mm high, 390mm wide, 285mm deep and weigh between 29.2 and 30.5kg. All the piping needed is within its footprint, and due to their low lift weight, they can be mounted on a sturdy hanging bracket.

Its modest size makes Baxi 800 combi boilers a great choice for properties with limited space.

If you would like to have a new Baxi 800 combi boiler or any other boiler installed, click here for more information.

How energy efficient are Baxi 800 combi boilers?


All Baxi 800 combi boilers are 93% efficient. This means that 93% of the energy they use goes into heating your home while only 7% is wasted, which is very good. To put this into context, many UK households are still using older boilers that are only 70-80% efficient, which means that up to 30% of their boiler’s energy will be wasted instead of being used to heat up their homes!

As Baxi 800 combi boilers are 93% efficient, they have an ErP “A” rating for heating and water, which makes them extremely efficient boilers.

ErP stands for Energy-related Products, and ErP ratings are part of European Union legislation. The main purpose of the legislation is to improve the performance standards of all products that use 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 a minimum of 90% efficient and G-rated products being less than 70% efficient.

A boiler’s efficiency is the percentage of the total energy used by the boiler to generate heating. As with all modern boilers, Baxi 800 combi boilers are condensing boilers. This means they are able to recover heat that was previously lost via the flue and use it to pre-heat the heating system.

Having a highly efficient condensing boiler like any in the Baxi 800 range could save you hundreds of pounds in heating bills every year while also reducing your household’s carbon emissions.

Baxi 800 key features

Easy to repressurise your central heating system

All Baxi 800 combi boilers are fitted with an Easy-Fill permanent filling loop. This is a single spring-loaded lever which allows householders to repressurise their central heating system quickly and easily without the need to call an engineer.

For more information on Baxi filling loops and how to repressurise a Baxi boiler, click here

Protects against sludge clogging up your central heating system

Adey Magna_clean_Filter

All Baxi 800 combi boilers are installed with an Adey Magnaclean Micro 2 magnetic system filter to provide excellent protection against sludge and debris clogging up central heating systems.

Sludge is a build up of rust particles that come from the inside of radiators and pipes due to corrosion. A sludge buildup could result in your boiler being less efficient, cause cold spots on your radiators, and could even cause your boiler to break down!

Adey Magnaclean Micro 2 magnetic system filters attract rust particles and stores them away from the central heating system to prevent the particles from disrupting the flow of water, as well as preventing them from turning into sludge.

Other benefits for having Adey Magnaclean Micro 2 magnetic system filter are:

  • Up to 6% annual savings on heating bills
  • Immediate ongoing central heating protection
  • Extends the life of the central heating system
  • Reduced carbon emissions

Let us fix your boiler.

At Smart Plan we have thousands of engineers up and down the country who are ready to fix your issue. We guarantee an engineer to your property within 48 hours.

OR 020 8146 3960

Can be operated using a smartphone


Baxi 800 combi boilers are compatible with Baxi uSense. Baxi uSense is a wifi 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

Can operate at lower temperatures to save fuel and money

When used with a Baxi In Flue Outdoor Sensor, Baxi 800 combi boilers could save you fuel and money.

Baxi’s In Flue Outdoor Sensor, or IFOS, is an outdoor sensor that clips on to the flue and takes temperature readings from outside the house in order to adjust the boiler's power output so it uses the minimum amount of energy necessary to heat up a home. 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 lower temperatures saves fuel, reduces carbon emissions without compromising user comfort and makes Baxi 800 combi boilers more efficient.

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!

10 year extended warranty


To give homeowners peace of mind, all the combination boilers in the Baxi 800 range come with a 10 year extended warranty, which is the maximum warranty length Baxi offers.

Baxi offering their longest warranty period shows the confidence they have in the performance and reliability of their 800 combi boiler range.

There are terms and conditions that you must follow in order to validate the extended warranty period.

To find out more about the terms and conditions, what a Baxi warranty does and does not cover and, for more information about Baxi warranties, click here.

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

Which Baxi 800 combi boiler is suitable for my property?

Baxi 800 combi boilers are available with hot water outputs of 25kW, 30kW, and 36kW, making them suitable for most property sizes.

Other than the type of boiler, there are three main factors to bear in mind when thinking about what size boiler is best suited to your property:

  • The number of radiators
  • The number of bedrooms
  • The number of bathrooms

Below is a rough guide to which Baxi 800 model is best suited to a property based on its power output.

Property Type Suitable Baxi 800 combi boiler
  • 1-2 bedrooms
  • 1 bathroom
  • Fewer than 5 radiators
  • Baxi 825
Small house
  • 1-2 bedrooms
  • 1 bathroom
  • 5-7 radiators
  • Baxi 825
Medium house
  • 2-3 bedrooms
  • 1 bathroom
  • 6-7 radiators
  • Baxi 830
Family house
  • 3-4 bedrooms
  • 1 bathroom
  • 1 ensuite
  • Up to 10 radiators
  • Baxi 836
Large family house
  • 4-5 bedrooms
  • 2 bathroom
  • 1 ensuite
  • Up to 15 radiators
  • N/A

It is important that you get the correct size boiler for your property and needs. If it is too small, your boiler will find it difficult to heat up your home and meet its hot water demands. If it is too big, your boiler may use more power than necessary, resulting in wasting energy and money.

Flow rate

Baxi 800 combi boilers come with these flow rates:

Baxi 825 10.2l/min
Baxi 830 12.2l/min
Baxi 836 15l/min

A good flow rate for a shower is between 10-15 litres per minute, which means that all boilers in the Baxi 800 range will be able to provide you with a good flow of hot water for your showers and baths, although with the 825 and 830 models, you may notice a slight drop in the water flow if more than one water outlet is being used at the same time.

Does your home have high hot water demands?

Although Baxi 800 combi boilers are suitable for most sized properties, they are not the best choice for larger households with high water demands. If you have high water demands but have limited space in your property, then the Baxi Platinum 40 combi or the Baxi Duo tec 40 combi might be a better choice. If you have high water demands and space isn’t an issue, then a Baxi heat only boiler may be more suitable.

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 determine the right boiler for your needs.

Baxi 800 Specifications

Baxi 825 Baxi 830 Baxi 836
Width 390mm 390mm 390mm
Height 700mm 700mm 700mm
Depth 285mm 285mm 285mm
Weight 29.2kg 29.2kg 30.5kg
Fuel Type Gas Gas Gas
Energy Rating (Heating) A A A
Energy Rating (Water) A A A
Boiler Plus ErP 93% 93% 93%
Flow Rate 10.2 l/min 12.2 l/min 15 l/min
Central Heating Max. Output 20 kW 20 kW 25 kW
Hot Water Max Output 25 kW 30 kW 36 kW
Sound Power Level 48 dB 48 dB 51 dB
Flue Outlet Position Top Flue Outlet Top Flue Outlet Top Flue Outlet
Warranty 10 years 10 years 10 years

Still need help with your Baxi boiler?

Call Smart Plan and speak to our expert engineering team free of charge.

0333 772 6247