Baxi 836 Combi Boiler Review

Company type: Manufacturer

HQ: Warwick, England

Founded: 1866

CEO: Karen Boswell

The Baxi 836 combi boiler is one of three combination boilers in the Baxi 800 range and boasts the highest hot water output within the range. Read this review to find out whether this small yet powerful combi boiler is the right boiler for your household's needs.

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Is the Baxi 836 the right size for my property

Hot water output


The Baxi 836 combi boiler is the most powerful combination boiler within the 800 range, with a maximum hot water output of 36kW. Such a high hot water output makes this combi boiler a great choice for family homes with 1 bathroom and an ensuite.

It is vital to get the correct size boiler for your home. If the boiler’s output is too low, it may struggle to heat up your radiators fully and meet the hot water needs of the whole house. On the other hand, if the boiler’s output is too powerful, you may find yourself getting higher utility bills, and nobody wants that!

There are three main factors that determine the correct size of boiler for your property:

  • Type of boiler
  • Number of bathrooms
  • Total number of radiators

Below is a rough guide to what size combi boiler is recommended for different sized properties

Property Type No. of Bedrooms No. of Bathrooms No. of Radiators Recommended Boiler Size
Apartment 1-2 1 Up to 5 24-26kW
Small house 1-2 1 Up to 7 24-26kW
Medium house 2-3 1 Up to 7 30-32kW
Family house 3-4 1 & 1 ensuite Up to 10 35-40kW

Baxi 836

Large family house 4-5 2 & 1 ensuite Up to 15 Heat only or system boiler

As you can see from the table above, the Baxi 836 is an ideal choice for family homes with a bathroom and an ensuite with up to 10 radiators

Flow rate

The Baxi 836 combination boiler has a flow rate of 15 litres per minute. A boiler’s flow rate refers to how much water can flow through the boiler and how fast it can come out of a tap or shower head once the boiler is working.

The flow rate for a good shower should be at between 12-15l/m, and the Baxi 836’s flow rate sits at the upper end of this scale, which means this boiler will still produce a strong flow of water if more than one tap or shower is turned on at the same time.

Does your home have high hot water demands?

The Baxi 836 combi boiler is a great choice for family homes with a bathroom and an ensuite, with limited space, but if you have high hot water demands and live in a larger property where space isn't an issue, then a Baxi Heat only boiler will better suit your needs.

Find the right boiler for your home

Where can the Baxi 836 be installed?

The Baxi 836 can easily be installed in all the usual places you would store a boiler, such as in the kitchen, in your loft, in your airing cupboard, and so on, but due to its compact size, it can easily be installed in a standard kitchen cupboard, saving you space, time and money!

The Baxi 836's modest size makes it a great choice for properties with limited space.

As with all combination boilers, a key benefit is their small size in comparison to regular and system boilers, which require a tank or cylinder to work.

The Baxi 836 boiler is 700mm high, 390mm wide, 285mm deep and has a low lift weight of only 29.2kg. It has all the piping needed within its footprint and is mounted on a simple yet sturdy hanging bracket.

How energy efficient is the Baxi 836?


The Baxi 836 is a 93% energy efficient boiler, which gives it an energy rating of “A” for heating and water, making it an extremely efficient boiler that meets and exceeds new boiler regulations.

A boiler’s efficiency is the percentage of the total energy used by the boiler to generate heating. As with all modern boilers, the Baxi 836 is a condensing boiler. This means it is able to recover heat that was previously lost via the flue to pre-heat the heating system.

In Baxi 836’s case, 93% of the energy it uses goes into heating your home while only 7% is lost or used to run itself, which is very good. To put this into comparison, many households around the UK are still using older boilers that are only 70% efficient, which means they lose a huge 30% of their energy to heat up a house!

Although the Baxi 836 has a very good energy efficiency rating of 93%, there are some boilers that boast even more impressive numbers, such as the Worcester Bosch Greenstar 4000 range that has an energy efficiency rating of 94% and the Vitodens 050-W 29kW which has an excellent energy efficiency rating of 97%.

How long is the warranty period for the Baxi 836?

The Baxi 836 comes with a 1 year parts and labour warranty as standard, but can be extended to 10 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 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.

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

Key features

Easy to repressurise your central heating system

The Baxi 836 is fitted with an Easy-Fill permanent filling link. 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.

Protects against sludge clogging up your central heating system

Baxi’s 836 boiler is installed with Adey’s Magnaclean® Micro 2 magnetic system filter. This compact filter is designed to easily fit into tight spaces and it provides excellent protection against sludge and debris clogging up the heating system.

Magnetic filters attract metal particles and store them away from your central heating system in order to prevent the particles disrupting the flow of water, as well as stopping them from eventually turning into sludge. A build up of sludge will result in your central heating system being less efficient, cause cold spots on radiators and even cause your boiler to break down.

Other benefits of having an 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

Smartphone control

Another key feature of the Baxi 836 combi boiler is its compatibility with Baxi uSense. Baxi uSense is a Wi-Fi thermostat that can be controlled by a smart device such as your phone, tablet, or even your Alexa!

Features of Baxi uSense are:

  • More control - Schedule your heating to fit in with your lifestyle
  • More flexibility - Control your heating from your smartdevice, 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 efficiencyand manage your bills

Easy to use OpenTherm digital interface

The Baxi 836 combi boiler is compatible with OpenTherm thermostats. OpenTherm thermostats are easy-to-use thermostats that have an in-built programmer that allows you to control your central heating with the scroll of the dial.

A main feature of this programmable thermostat is its load compensation function. This function measures the difference between what the indoor temperature is and what temperature the user wants and modulates the boiler so that it uses the minimum amount of fuel necessary to close the gap, resulting in you saving money!

Baxi 836 Specifications

Width 390mm
Height 700mm
Depth 285mm
Weight 30.5kg
Fuel TypeGas
Display TypeLCD
Energy Rating (Heating)A
Energy Rating (Water)A
Flow Rate15 l/min
Central Heating Max. Output25 kW
Hot Water Max. Output36 kW
Sound Power Level51 dB
Flue Outlet PositionTop
Warranty10 years

Need more help with your Baxi boiler?..

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

Still need help with your Baxi boiler?

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

0333 772 6247