Baxi is a well-established UK boiler manufacturer, and the Baxi 800 is one of its combi boiler ranges. The range is available in three outputs, giving homeowners different options depending on their heating and hot water requirements.
The Baxi 800 also includes features such as a magnetic system filter and EasyFill top-up system. Before choosing a model, it is important to consider the size of your home, hot water demand and available installation space.
- Content Guide
- » Baxi Combi Boiler Models
- » Where Is the Best Place to Install a Baxi 800 Combi Boiler?
- » Features and Benefits of the Baxi 800 Combi Boiler
- » Are Baxi 800 Combi Boilers Energy Efficient?
- » Baxi 800 Combi Boiler Flow Rates
- » What Does the Flow Rate Mean for Your Home?
- » Is the Baxi 800 Suitable for High Hot Water Demand?
- » Professional Baxi Boiler Installation in London
- » Baxi 800 Combi Boiler FAQs
Baxi Combi Boiler Models
The Baxi 800 combination boiler range includes three models:
Baxi 825
The Baxi 825 has a 25kW output and is aimed at smaller homes and properties with moderate heating and hot water demand.
Baxi 830
The Baxi 830 has a 30kW output and is suited to medium-sized homes with greater heating and hot water requirements.
Baxi 836
The Baxi 836 is the largest model in the range, with a 36kW output. It is intended for homes with higher heating and hot water demand.
When talking about boiler "size", the kW rating refers to the boiler's power output. A higher output can provide greater heating and hot water capacity, but the right size depends on the property and how much hot water you use.
If you are comparing different models before making a decision, our guide to the best combi boilers in the UK provides a wider comparison.
Before replacing an existing boiler, have the property assessed by a qualified professional so the boiler output and installation requirements can be checked properly.
Where Is the Best Place to Install a Baxi 800 Combi Boiler?
The Baxi 800 can be installed in common locations such as a kitchen, loft or airing cupboard. Its compact dimensions also make it suitable for installation inside a standard kitchen cupboard where the required clearances and installation conditions allow it.
The boiler measures approximately 700mm high, 390mm wide and 285mm deep, with the weight varying slightly between models.
One advantage of a combi boiler is that it does not require a separate hot water storage cylinder or cold water tank. This can make the Baxi 800 useful where storage space is limited.
However, the final installation position should be confirmed by the installer. Flue routing, ventilation, access, condensate drainage and manufacturer requirements all need to be considered.
Features and Benefits of the Baxi 800 Combi Boiler
10-Year Warranty
The Baxi 800 can come with a 10-year parts and labour warranty. The exact warranty available can depend on the installation and manufacturer terms, so this should be confirmed when purchasing.
Filter for Extra Protection
The range includes an Adey Micro 2 magnetic filter, designed to help protect the boiler and central heating system from debris and magnetite.
EasyFill Top-Up System
The EasyFill system makes it easier to top up central heating pressure when required, potentially reducing the need for an engineer visit for a simple pressure adjustment.
Pre-Heated Condensate Trap
The Baxi 800 includes a pre-heated condensate trap designed to reduce the risk of condensate-related freezing problems during cold weather.
Natural Gas and LPG Compatibility
The Baxi 800 range can be used with natural gas or LPG, subject to the appropriate installation requirements.
External Pressure Gauge
An external analogue pressure gauge allows you to check the boiler's system pressure and identify when the system may need topping up.
Are Baxi 800 Combi Boilers Energy Efficient?
The Baxi 800 is a condensing boiler with an ErP A rating and a 93% efficiency figure.
Condensing boilers recover heat from the flue gases that would otherwise be lost. This helps improve efficiency compared with older, less efficient boiler technology.
Actual energy use and heating costs will still depend on factors such as the property's insulation, heating controls, boiler settings and how the system is used.
Baxi 800 Combi Boiler Flow Rates
The three Baxi 800 models have different hot water flow rates:
- Baxi 825: 10.2 litres per minute
- Baxi 830: 12.2 litres per minute
- Baxi 836: 15 litres per minute
Flow rate is important when choosing a combi boiler because it affects how much hot water the boiler can deliver at a given time.
What Does the Flow Rate Mean for Your Home?
The Baxi 825 and 830 can be suitable for homes with moderate hot water demand. If several outlets are likely to be used at the same time, hot water performance can be affected.
The higher flow rate of the Baxi 836 makes it more suitable for properties with greater hot water demand, although incoming mains water flow and pressure also affect the result.
For this reason, boiler output should not be selected by radiator count alone. The property and its hot water requirements should be assessed before installation.
Is the Baxi 800 Suitable for High Hot Water Demand?
The Baxi 800 range can work well in small and medium-sized homes, but a combi boiler may not be the best option for every larger property.
If hot water demand is high, alternatives such as a higher-output combi or a system with stored hot water may be worth considering. The right choice depends on the property's available space, mains water supply and expected demand.
A professional survey can help establish which type and size of boiler is appropriate.
Professional Baxi Boiler Installation in London
Serviceteam provides professional boiler installation in London, including advice on choosing a suitable boiler and commissioning the new system.
Our service includes:
- Free, no-obligation quotes
- Advice based on the property's heating and hot water requirements
- Professional boiler installation and commissioning
- Manufacturer warranty support, subject to the applicable terms
If you are considering replacing your current boiler, our boiler installation service in London can help you assess the options before choosing a model.
Baxi 800 Combi Boiler FAQs
How effective is a Baxi 800 combi boiler?It's a condensing boiler with an ErP A rating and a stated 93% efficiency figure. Actual performance depends on the installation, controls and how the heating system is operated.
How many radiators can a Baxi 800 run?The Baxi 800 can support up to 20 radiators. However, radiator count alone is not enough to determine whether a boiler is correctly sized — the property's heat loss and hot water requirements should also be considered.
What is the most efficient setting for a Baxi boiler?For maximum efficiency, most heating engineers now recommend a lower flow temperature, generally between 50–60°C, since condensing boilers run most efficiently at lower settings. A higher setting around 65°C may still be needed to adequately heat a hot water cylinder or during colder weather. The most suitable setting depends on the system, controls and property, so the manufacturer's guidance and the installer's recommendations should be followed.
