The smarter way to replace your boiler

  • Get FREE Quotes today
  • Compare quotes & save money
  • Over 5,000 engineers across the UK
Tell us about your job
Get Free Quotes

Navien LCB700 Blue Flame System Oil Boiler

The Navien LCB700 System is an exceptional boiler with pioneering design features and includes both internal and external options.

Ideal for all sizes of homes, the Navien LCB700 System is a lightweight floor-standing oil boiler available in a range of outputs to suit your requirements. You have the choice of either an internal or external model and will receive a generous warranty when you choose to have this system boiler installed. In addition to offering complete flexibility for installation, this boiler boasts blue flame technology for maximum efficiencies. 

How Much Does this Boiler Cost?

Navien’s LCB700 System is available in 21kW, 28kW and 36kW outputs and will cost you anything between £1,585 and £2,130. The external models are a bit more expensive than the internal ones, and you also have to pay a qualified engineer to install your new oil boiler. Oil system boiler installation costs can vary enormously, but you can compare prices by getting a fixed-price quote from different local and national installers. 

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

Oil system boilers can meet the hot water demands of larger homes and require a separate cylinder for storing, meaning they need more space than an oil combi boiler. System boilers, like the LCB700 System, are perfect for homes with more than one bathroom and those that use a lot of hot water at once. If you choose an internal model, it will fit neatly between your kitchen or utility units. But if you don’t have much space to play with, you can opt for an external model.  

Before purchasing a new boiler, you must determine the correct size/output for your needs. As a general rule, the more radiators, taps, showers and baths you have, the higher the boiler output you need. If you want to be sure of the correct boiler size for your home, ask a qualified heating engineer for their recommendation. 

Is it a High Efficiency Boiler?

The Navien LCB700 System is a highly efficient boiler with an ErP A rating and an efficiency rating of 93%. Furthermore, this system boiler is an Energy Saving Trust endorsed product that comes complete with a high-efficiency circulating pump. 

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

Yes. The Navien LCB700 System with a lightweight design for easy installation has a full-text driven control panel to help you control heating and hot water temperatures and a stainless steel heat exchanger to prevent corrosion and extend the boiler’s life. It offers revolutionary blue flame technology, which guarantees superior efficiencies and ultra-low NOx emissions. This modern system boiler can even check the weather forecast and adjust itself accordingly to ensure your home maintains a comfortable temperature. The LCB700 System also comes complete with a factory fitted expansion vessel and a combined pressure relief valve and condensate drain.   

How long is the Warranty on this Boiler?

You will receive a generous 10-year warranty as standard when you choose to have the Navien LCB700 System boiler installed. 

Summary of Important Information

  • Expect to pay between £1,585 and £2,130
  • 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

The Navien LCB700 System is a powerful oil-fired boiler that can meet the hot water requirements of homes with multiple bathrooms. For now, we will leave you to check out the pros and cons of getting this system boiler installed with our list below. 


  • 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
Get Boiler Quotes

Get Free Quotes Today