Baxi heat only boilers
A good choice for most property sizes

Company type: Manufacturer

HQ: Warwick, England

Founded: 1866

CEO: Karen Boswell

Baxi boilers have been designed to make life easier for the installer, and Baxi heat only boilers are no exception. Said to be the lightest boilers in the UK, their compact size and straight forward installation make them a popular choice for boiler installers around the UK. Here, we see why Baxi heat only boilers are also a good choice for homeowners.

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What is a heat only boiler?

Heat only boilers provide the heat that is used in your central heating system. Cold water is fed to a hot water cylinder, which is then heated by the boiler to supply water for your central heating and taps.

Heat only boilers, also known as regular, conventional, traditional, or open-vent boilers, are very common within large family homes with a high demand for hot water as they enable households to run several appliances and use hot water taps at the same time without experiencing a significant drop in pressure.

Heat only boilers need more space to operate than combination boilers as the whole heating system consists of these other components:

A hot water cylinder - Used for storing hot water for on-demand use. Usually located in the airing cupboard.

A cold water storage cistern - Supplies cold water to the hot water cylinder. Must be stored above the hot water cylinder in order to gravity-feed water to it. Usually stored in the loft.

A feed and expansion cistern - Maintains the appropriate level of water in the central heating system and accommodates the expansion of water when it is heated by the boiler. Usually stored next to the cold water storage cistern.

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What Baxi heat only boilers are available?


There are three different Baxi heat only boiler models available on the market today: Baxi 400 heat, Baxi 600 heat and Baxi 800 heat. Each model is similar in terms of features, with the most noticeable differences being:

  • The different boiler sizes available
  • The length of warranty offered with each model
  • The Baxi 800 heat only boiler comes with an Adey Micro 2 magnetic system filter for protection against magnetite and other debris clogging up the heating system

What different size Baxi heat only boilers are available?

Each Baxi boiler heat only model is available in a number of sizes:

  • Baxi 400 is available in 12kW, 15kW, 18kW, 24kW and 30kW
  • Baxi 600 is available in 13kW, 16kW, 19kW, 25kW and 30kW
  • Baxi 800 is available in 16kW, 25kW and 30kW

Boiler size refers to the heat output of the boiler and is measured in kilowatts (kW). As a general rule of thumb, the more heat and hot water requirements a property needs, the higher the power output of the boiler needs to be.

Baxi heat only boilers

What key features come with a Baxi heat only boiler?

Compatible with top of the range hot water cylinders

Baxi heat only boilers are compatible with a number of top-of-the range hot water cylinders, including Megalfo Eco Cylinders. Megaflo Eco Cylinders are highly efficient hot water cylinders that provide fast filling baths and a more balanced water supply to showers and taps, as they are directly fed from the mains water supply to deliver a strong flow of hot water.

Lightweight and compact design

According to Baxi, Baxi heat only boilers are the lightest boilers available on the UK market, weighing in at only 17.4kg. Baxi heat only boilers 370mm wide, 625mm tall and 270mm deep. With its low lift weight and compact size, Baxi heat only boilers can easily be installed in a standard kitchen cupboard, which can save you space, time and money!

No risk of boiling water after the boiler has turned off

Baxi heat only boilers use aluminium heat exchangers that have been designed to be thinner so they react faster when the boiler is switched off, meaning the risk of boiling water after the boiler has been turned off is eliminated, so there is no need for a pump overrun on any Baxi heat only boiler!

Pump overrun is a normal feature on most boilers. Pump overrun is when the pump continues to run for a short period after the boiler has switched off in order to evaporate any leftover heat so that it doesn’t damage your boiler’s components, such as the heat exchanger.

As pumps are normally installed next to the hot water cylinder, the boiler installer needs to run a wire from the pump to the boiler, which is often located in another part of the house and could involve disruption by lifting carpets and floorboards.

Less disruption and possibly more money savings

Because Baxi heat only boilers don’t require a pump overrun that needs power when the boiler is turned off, it saves the installer the problem of getting a permanent power supply to the boiler, resulting in less disruption to the installer, and the homeowner and possibly saving money on utility bills as electricity isn't being supplied to the pump after the boiler is switched off!

Baxi 800 heat models include a filter to protect the boiler and the heating system

Baxi 800 heat models are supplied with Adey’s Magnaclean® Micro 2 magnetic system filter. Adey’s Magnaclean filter is a compact yet powerful filter that provides great protection against sludge and debris clogging up your heating system.

Magnetic filters attract metal particles and keep them away from your central heating system in order to prevent them 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.

How energy efficient are Baxi heat only boilers?


All the models within the Baxi heat only boiler range have an ErP A-rating, making them highly efficient boilers.

ErP stands for Energy-related Products and these 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.

As of April 2018, all new boilers have to be at least 92% efficient, so Baxi heat only boilers meet and exceed this requirement.

While purchasing a brand new Baxi heat only boiler may seem a large upfront cost, it could help you lower your heating bills considerably in the long term.

How much do Baxi heat only boilers cost?

Baxi heat only boiler prices will vary in price depending on where you purchase the boiler, but we have put this table together to give you a rough idea of how much each model may typically cost you.

Model Sizes Typical price
Baxi 400 12-30kW £695-£895
Baxi 600 13-30kW £799-£985
Baxi 800 16-30kW £990-£1250

Please note, prices are for the boiler only and do not include installation costs or additional items that may be needed

Which Baxi heat only boiler is suitable for my property?

Which Baxi heat only boiler you require depends on many factors, such as how well a property is insulated and the size of the property but it mainly depends on your hot water and central heating demands.

This table will give you a rough idea of which Baxi heat only boiler is the right size for your property based on the number of baths/showers and radiators it'll need to provide for.

Property Type Suitable Baxi Heat only boiler
  • 1-2 bedrooms
  • 1 bathroom
  • Fewer than 5 radiators
  • Baxi 412/415
  • Baxi 613/616
  • Baxi 816
Small house
  • 1-2 bedrooms
  • 1 bathroom
  • 5-7 radiators
  • Baxi 415/418
  • Baxi 616/619
  • Baxi 816
Medium house
  • 2-3 bedrooms
  • 1 bathroom
  • 6-7 radiators
  • Baxi 418/424
  • Baxi 619/625
  • Baxi 825
Family house
  • 3-4 bedrooms
  • 1 bathroom
  • 1 ensuite
  • Up to 10 radiators
  • Baxi 424/430
  • Baxi 625/630
  • Baxi 825/830
Large family house
  • 4-5 bedrooms
  • 2 bathroom
  • 1 ensuite
  • Up to 15 radiators
  • Baxi 430
  • Baxi 630
  • Baxi 830

Regular boilers do not need to be as powerful as combination boilers as they store hot water in the hot water cylinder ready for later use, whereas a combination boiler needs a higher power output as it needs to heat up and produce hot water on demand.

Heat only boilers are not ideal if space is limited, as the other components needed for them to operate, such as the cold water tanks and hot water cylinder, take up valuable space.

If space is an issue then you may want to look at combination boilers such as the Baxi Platinum combi boiler, Baxi Duo tec combi boiler, or Worcester Bosch Greenstar 30i.

You may want to consider a Baxi heat only boiler if any of the following relate to you:

  1. You have high hot water demands
  2. You have multiple bathrooms
  3. You live in an area that suffers from low water pressure
  4. Your old central heating system can not tolerate hugh water pressure
  5. You want to replace your old heat only boiler with a more efficient model

Baxi heat only boilers are a great choice for larger homes with high hot water demands, for example, households that may need to run a bath, a shower and the dishwasher at the same time.

What warranty duration will I get with my Baxi heat only boiler?

Baxi heat only boilers come with a 1 year parts and labour warranty as standard, but they can be extended to up to 10 years, depending on the model. Below is a table to show you the different extended warranty durations for each model.

Model Extended warranty duration
Baxi 400 5 years
Baxi 600 7 years
Baxi 800 10 years

In order to extend your Baxi heat only boiler's warranty, you must follow these three steps:

  1. Register your warranty with Baxi within 30 days of installation
  2. Make sure your Baxi boiler is installed by a Gas Safe registered engineer who must complete a benchmark commissioning checklist
  3. Have your boiler serviced once a year by a Gas Safe engineer in line with Baxi's instructions

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

Still need help with your Baxi boiler?

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

0333 772 6247