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Navien LCB700 Blue Flame Regular Oil Boiler

Suited to larger properties, the Navien LCB700 Regular is an easy to install upgrade for an older system.

If you have a traditional heating system at home, the Navien LCB700 Regular oil-fired boiler could be the ideal replacement. It offers blue flame technology for superb efficiencies and is perfect for installation next to your kitchen or utility units. However, this boiler doesn’t have to be installed indoors because you can choose between internal and external options, as well as a range of outputs to suit your requirements. 

How Much Does this Boiler Cost?

The Navien LCB700 Regular comes with a 21kW, 28kW or 36kW output and will set you back anything between £1,445 and £1,980, not including installation. All external models cost a bit more than the internal versions, but there isn’t much price difference. As oil regular boiler installation costs can vary, we recommend comparing prices by getting quotes from local and national installers. Always ask for a fixed-price quote that includes the cost of a new boiler and the installation.  

How will I know if this Boiler is Suitable for My Home?

Navien’s LCB700 Regular is a modern oil-fired regular boiler that requires tanks in your roof space and a separate cylinder for storing hot water, making it unsuitable for homes where space is limited. This regular boiler includes internal and external options and is suited to homes with multiple bathrooms and those looking to upgrade a traditional heating system. 

You must select the correct boiler size/output for your property and will likely need to seek advice from a qualified heating engineer. An engineer can visit you in your home to determine the most suitable boiler size (kW output) for your needs.  

Is it a High Efficiency Boiler?

Yes. The Navien LCB700 Regular is a 93% energy efficient oil boiler with an ErP A rating. This boiler is also endorsed by the Energy Saving Trust, an independent organisation and a trusted voice on energy efficiency.  

Does this Boiler have a Good Range of Controls and Features?

It does. The Navien LCB700 Regular has a built-in control panel for easy setup and programming and a stainless steel heat exchanger to prevent corrosion and increase boiler lifespan. It features a blue flame burner for maximum efficiencies and a smart forecast check that monitors the weather forecast and adjusts the boiler accordingly. This regular boiler also boasts geofencing capabilities and will turn on or off based on your location so that you can benefit from maximum comfort. 

How long is the Warranty on this Boiler?

If you choose to have the Navien LCB700 Regular installed, it will come with a generous 10-year warranty as standard.

Summary of Important Information

  • Expect to pay between £1,445 and £1,980
  • Heating output of 21kW, 28kW or 36kW
  • Internal models dimensions: 860mm (H) x 600mm (W) x 470mm (D)
  • External models dimensions: 882mm (H) x 673mm (W) x 515mm (D)
  • Uses oil as its fuel source
  • A-rated for efficiency
  • 10-year warranty as standard

Pros and Cons

Navien’s LCB700 Regular is designed with installers and end-users in mind and boasts zone control, a two-channel program and a text-driven display to indicate boiler issues. It gives you everything you could want from a regular boiler, but don’t forget that you need enough space to store tanks in your loft and a separate cylinder. Below are the pros and cons of getting this boiler installed. 


  • Suited to small, medium and large-sized homes with multiple bathrooms
  • Internal and external models
  • Blue flame technology – guarantees superior efficiency and ultra-low NOx emissions
  • Stainless steel heat exchanger – prevents corrosion and helps extend the lifespan of the boiler
  • Smart forecast check – the boiler checks the weather and adjusts itself accordingly
  • Smart control panel – gives you full control of heating and hot water temperatures
  • Compatible with Smart Plus controllers – regulates heating according to changes in outside temperature and enables geofencing via an app to let your location automatically take care of your heating
  • Self-diagnosis and error feedback feature – offers a quick troubleshooting guide
  • Combined pressure relief valve and condensate drain – fast and simple installation
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Energy Saving Trust endorsed product
  • Great rating on Trustpilot – correct at the time of writing – February 2022
  • 10-year parts and labour warranty


  • Requires separate cylinder and loft tanks
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