APN Boilers helps homeowners find experienced heating professionals who can assess the complete system and recommend an appropriate Navien boiler installation.

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Is a Navien Boiler Suitable for Your Home?

 

A Navien boiler may be worth considering where a homeowner wants:

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• A compact gas combi boiler

• Stronger instantaneous hot-water performance

• A combi suitable for a larger family home

• A system boiler connected to a hot-water cylinder

• Stainless-steel heat exchangers

• Natural gas or LPG compatibility

• App-based heating and hot-water controls

• Weather forecasting and geofencing

• Control of several heating zones

• A longer manufacturer warranty on selected models

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Different Navien boilers are designed for very different properties. The entry-level NCB300 is aimed primarily at smaller homes, while the NCB500 ON and NCB700 ON focus more heavily on family-sized and higher-demand hot-water installations.

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The quality of the completed heating system will still depend on correct design, installation, cleaning, commissioning and control selection.

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Navien Combi Boilers

 

A Navien combi boiler provides central heating and instantaneous hot water from one appliance.

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It does not normally require a separate hot-water cylinder or cold-water storage tank. This can release storage space and simplify the heating arrangement.

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A combi boiler may be suitable for:

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• Flats and apartments

• Smaller houses

• Family homes with a suitable mains-water supply

• Properties already using a combi boiler

• Homes where tanks and cylinders are being removed

• Projects where installation space is limited

• Households wanting hot water without waiting for a cylinder to reheat

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Navien’s current gas combi selection ranges from the compact NCB300 to the higher-performance NCB500 ON and NCB700 ON crossover products.

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Check the Water Supply Before Choosing a Combi

 

A high-output Navien combi boiler cannot create better incoming water pressure.

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The boiler can only heat and deliver the volume of water reaching the property. A powerful boiler connected to a restricted water main may still provide poor shower and bath performance.

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Before recommending a Navien combi boiler, the installer should test:

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• Static mains-water pressure

• Dynamic pressure while outlets are operating

• Incoming flow rate in litres per minute

• Diameter of the incoming water main

• Condition of the internal water pipework

• Number of showers and bathrooms

• Likelihood of several outlets being used together

• Distance between the boiler and hot-water outlets

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This is particularly important when considering the NCB500 ON or NCB700 ON. Their quoted hot-water performance assumes that the property can supply the required volume of incoming water.

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Navien NCB300 Combi Boiler

 

The NCB300 is Navien’s entry-level gas combi boiler and is primarily intended for smaller properties.

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It is available in 28kW, 30kW, 37kW and 41kW domestic hot-water outputs. Navien broadly rates these models from one shower through to two showers and an additional tap, although actual performance depends on the property’s water supply.

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Current features include:

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• Compact wall-mounted design

• Stainless-steel heat exchangers

• Natural gas and LPG compatibility

• Smartphone-compatible controls

• Weather forecasting

• Geofencing

• Extended flue options

• Five-year parts-and-labour warranty

• 20% hydrogen-blend compatibility

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The NCB300 may be considered for:

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• Flats

• Apartments

• Smaller houses

• Direct combi replacements

• Homes with one main bathroom

• Properties requiring an LPG boiler

• Installations where cupboard or wall space is restricted

• Homeowners seeking an accessible entry into the Navien range

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The 37kW and 41kW model names relate primarily to their domestic hot-water output. The maximum central-heating output is lower, which can help avoid supplying unnecessarily high output to the radiators.

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Navien NCB500 ON Combi Boiler

 

The NCB500 ON is designed as an all-round family-home combi boiler with stronger hot-water performance than a basic replacement appliance.

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Current models include 30kW, 32kW, 37kW and 41kW domestic hot-water outputs. Depending on the model, Navien publishes hot-water flow rates ranging from approximately 12.3 to 16.8 litres per minute at a 35°C temperature rise.

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Current features include:

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• Compact kitchen-cupboard dimensions

• Built-in digital display

• Energy-usage information

• Stainless-steel heat exchangers

• Flow-adjustment and automatic mixing valves

• Natural gas and LPG compatibility

• Smartphone control

• Weather forecasting

• Geofencing

• Control of up to three zones with the appropriate control pack

• Ten-year parts-and-labour warranty

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The NCB500 ON may suit:

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• Medium-sized family homes

• Properties with one bathroom and an ensuite

• Homes requiring stronger bath-filling performance

• Replacement of an existing higher-output combi

• Households wanting app-based controls

• Properties divided into several heating zones

• Homeowners looking for a longer available warranty

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Navien describes the NCB500 ON as a crossover combi because it is designed to prioritise consistent hot-water performance while retaining the space-saving benefits of a combi boiler.

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It remains essential to test the incoming mains supply. The boiler cannot deliver 15 or 16 litres per minute if substantially less water reaches the property.

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Navien NCB700 ON Combi Boiler

 

The NCB700 ON is Navien’s higher-performance gas combi boiler and is aimed at larger properties with substantial hot-water demand.

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Navien states that the NCB700 ON can supply hot water to three bathrooms simultaneously and achieve flow rates of up to 22 litres per minute at a 35°C temperature rise. The boiler has a maximum domestic hot-water output of 54kW and includes an integral hot-water recirculation pump.

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Current features include:

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• Maximum hot-water flow of up to 22 litres per minute

• Built-in domestic hot-water recirculation

• NaviCirc hot-water return technology

• Stainless-steel heat exchangers

• 15:1 turndown ratio

• Natural gas and LPG compatibility

• Control of up to three heating zones

• Smartphone-compatible controls

• Twelve-year warranty

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The NCB700 ON may be considered for:

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• Larger family homes

• Properties with several bathrooms

• Homes with long hot-water pipe runs

• Households regularly using several outlets

• Properties where a separate cylinder is undesirable

• Replacement of an older storage combi

• Projects requiring stronger hot-water circulation

• Homeowners seeking a high-specification Navien boiler

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The manufacturer’s three-bathroom claim must be considered alongside the actual water supply. The property will require sufficient dynamic pressure, incoming flow and suitable pipe sizes to support that level of performance.

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Where the water supply is restricted, a system boiler with a correctly sized cylinder may remain the more appropriate solution.

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What Is a Crossover Combi Boiler?

 

Navien uses the term crossover combi for boilers intended to bridge part of the gap between a conventional combi and a stored-hot-water system.

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The NCB ON range is designed to prioritise hot-water performance through additional flow control, mixing and, on the NCB700 ON, domestic hot-water recirculation technology.

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Potential benefits can include:

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• No separate hot-water cylinder

• Reduced waiting time for hot water

• Stronger flow to suitable outlets

• More consistent water temperature

• Space released within an airing cupboard

• Modern digital controls

• Improved performance in larger homes

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However, a crossover combi is not automatically superior to a system boiler.

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A cylinder may still provide the better solution where:

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• The property has several large bathrooms

• Multiple showers are used frequently

• The incoming water main is restricted

• There is already a suitable unvented cylinder

• The household requires substantial stored hot water

• Renewable heating may be added later

• An immersion-heater backup is desirable

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The final decision should follow a proper water and hot-water demand assessment.

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Navien System Boilers

 

A Navien system boiler heats the radiators and works with a separate hot-water cylinder.

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Instead of producing all hot water instantaneously, the boiler heats and stores it within the cylinder. This can make a system boiler more appropriate for properties with several bathrooms or high simultaneous demand.

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The current NCB500 System Boiler is available in 15kW, 18kW, 24kW and 30kW outputs. It uses stainless-steel heat exchangers, has compact cupboard-compatible dimensions and includes a ten-year warranty.

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A Navien system boiler may suit:

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• Larger houses

• Properties with two or more bathrooms

• Homes with an existing unvented cylinder

• Households using several showers

• Properties requiring stored hot water

• Heating systems divided into several zones

• Homes where an immersion-heater backup is useful

• Projects where future heating changes are being considered

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The boiler and cylinder must be designed together.

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The installer should assess:

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• Cylinder capacity

• Cylinder recovery time

• Incoming water pressure

• Incoming water flow

• Expansion arrangements

• Motorised valves

• Heating zones

• Cylinder thermostat

• Hot-water programming

• Existing pipe sizes

• System-water condition

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The NCB500 System Boiler is compatible with Navien’s Smart Plus controls and can control up to three zones when installed with the appropriate control package.

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Navien Boiler Prices

 

Navien boiler prices vary according to the model, output, controls, flue arrangement, warranty and installation package.

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Current retailer listings show some NCB300 boiler-only models at approximately £626 to £818 including VAT, while a 37kW NCB500 has recently been listed at approximately £1,097 including VAT. Higher-performance NCB700 packages can cost substantially more. Retail prices and availability change regularly.

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One national installer currently advertises:

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• NCB300 installations from approximately £1,840

• NCB500 installations from approximately £2,249

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These advertised starting prices relate to defined installation packages and will not apply to every property.

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For general homeowner budgeting, the following allowances may be useful:

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Navien boiler installation   /   Indicative installed cost

Straight forward NCB300 replacement £1,800–£2,800

NCB500 ON combi replacement £2,200–£3,600

NCB700 ON installation £3,500–£5,500+

NCB500 system-boiler replacement £2,500–£4,200

Boiler relocation £3,500–£5,500+

Traditional system converted to combi £3,500–£6,500+

New system boiler and cylinder £4,500–£8,000+

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These are broad planning allowances rather than fixed APN quotations. The NCB700 range can involve additional hot-water return pipework and commissioning, depending on how its recirculation features are used.

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What Affects a Navien Boiler Price?

 

The boiler unit is only one part of the overall installation cost.

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The final Navien boiler price may be affected by:

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• Boiler model and output

• Combi or system-boiler arrangement

• Existing boiler position

• Proposed new location

• Flue length and route

• Roof or high-level access

• Scaffolding

• Gas-pipe size

• Condensate drainage

• Hot-water return pipework

• Electrical alterations

• Smart heating controls

• Number of heating zones

• Magnetic system filter

• System cleaning or flushing

• Chemical inhibitor

• Radiator replacement

• Removal of tanks and cylinders

• Installation of a new cylinder

• Floor and wall access

• Making good and decoration

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A headline boiler price may only cover a straightforward appliance replacement in the same position.

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The written quotation should identify whether it includes the boiler, flue, filter, controls, cleaning, electrical work, certification and removal of the existing appliance.

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Navien Boiler Replacement

 

A Navien boiler replacement may be relatively straightforward where the new appliance remains in the same position and the existing heating-system type is retained.

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However, the installer should assess more than the old boiler dimensions.

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The pre-installation inspection should cover:

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• Existing boiler type

• Existing and proposed location

• Flue route

• Gas supply

• Condensate drainage

• Heating flow-and-return pipes

• Hot-water pipes

• Incoming water pressure and flow

• Radiators and valves

• Hot-water cylinder

• Storage tanks

• Electrical supply

• Heating controls

• System-water condition

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A new boiler connected to dirty, restricted or poorly balanced pipework may not produce the anticipated improvement.

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Where an NCB500 ON or NCB700 ON is being selected for its hot-water performance, the installer should demonstrate that the incoming water main and distribution pipework can support the expected flow.

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Converting to a Navien Combi Boiler

 

Homeowners with a traditional boiler, hot-water cylinder and roof tanks may want to convert to a Navien combi boiler.

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This can release storage space and remove the need to heat a separate cylinder, but it is considerably more involved than a direct boiler replacement.

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The conversion may require:

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• Removal of the existing boiler

• Disconnection of the hot-water cylinder

• Removal or abandonment of storage tanks

• New hot and cold-water connections

• Heating flow-and-return alterations

• Upgraded gas pipework

• New condensate drainage

• Revised flue arrangements

• Electrical alterations

• New heating controls

• System cleaning

• Making good

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The incoming water supply must be tested before the tanks and cylinder are removed.

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A standard NCB300 may work well for a smaller property. An NCB500 ON or NCB700 ON may be considered where the household needs stronger hot-water performance, while an NCB500 System Boiler and cylinder may remain preferable for very high or simultaneous demand.

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Choosing the Correct Navien Boiler Size

 

The boiler should not be selected by bedroom numbers alone.

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The installer should consider:

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• Property dimensions

• Construction type

• Insulation levels

• Heat loss through walls, roof and floors

• Window sizes and glazing

• Number and output of radiators

• Underfloor-heating zones

• Number of bathrooms

• Incoming water flow

• Hot-water usage

• Planned extensions or loft conversions

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Combi boiler model numbers are often driven by the domestic hot-water output rather than the central-heating requirement.

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For example, a homeowner may need a 37kW or 41kW combi to achieve the desired hot-water flow even though the radiators require considerably less output.

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The installer should therefore consider both the maximum hot-water output and the boiler’s minimum central-heating output. Correct modulation and commissioning can help prevent unnecessary cycling during periods of low demand.

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Navien Smart Heating Controls

 

Navien boilers can be combined with the manufacturer’s Smart Plus control systems.

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Current Smart Plus features include:

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• Smartphone heating control

• Hot-water scheduling

• Energy-consumption monitoring

• Weather forecasting

• Geofencing

• Control of up to three zones

• Remote adjustment of heating temperatures

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The Smart Plus ON AI Controller is designed specifically for the NCB500 ON and NCB700 ON. Its features include smart diagnosis, monthly energy reports and wireless firmware updates.

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Controls should be considered as part of the heating-system design rather than added after installation.

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A larger home may benefit from separate zones for different floors or areas. This avoids heating the entire property whenever only one part is occupied.

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Navien Boiler Warranties

 

Warranty periods vary by boiler model.

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Current manufacturer information lists:

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• NCB300: five-year parts-and-labour warranty

• NCB500 ON: ten-year parts-and-labour warranty

• NCB700 ON: twelve-year warranty

• NCB500 System Boiler: ten-year warranty

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Navien states that warranty cover is subject to annual servicing from the installation date. The manufacturer also provides a serial-number warranty lookup for homeowners.

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Warranty registration can be completed using the boiler’s registration card or completed Benchmark Commissioning Checklist.

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Homeowners should ask the installer to confirm:

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• Exact warranty length

• Who will register the boiler

• Registration deadline

• Annual servicing requirements

• Whether specified controls or filters are required

• What documents must be retained

• Who should be contacted if a fault develops

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The final warranty should be stated clearly within the quotation.

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Gas Safe Navien Boiler Installation

 

A Navien gas boiler must be installed by a suitably qualified Gas Safe registered engineer.

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Following installation, the homeowner should normally receive:

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• Completed Benchmark commissioning documentation

• Building Regulations compliance certificate

• Navien warranty confirmation

• Boiler instructions

• Heating-control instructions

• Annual service information

• Itemised invoice

• Relevant electrical certification

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Gas Safe Register explains that the Building Regulations Compliance Certificate belongs to the property and should be retained because it may be required during a future sale or remortgage.

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What Should a Navien Boiler Quote Include?

 

A proper quotation should identify:

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• Exact Navien model

• Boiler output

• Combi or system arrangement

• Proposed location

• Flue arrangement

• Domestic hot-water performance

• Heating controls

• Heating zones

• Hot-water recirculation work

• Magnetic system filter

• System cleaning

• Chemical inhibitor

• Gas-pipe alterations

• Condensate drainage

• Electrical work

• Removal of the existing boiler

• Removal of tanks or cylinder

• Making good

• Warranty period

• Commissioning

• Certification

• VAT

• Exclusions

• Potential additional costs

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This makes it easier to compare quotations on a like-for-like basis.

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A cheaper quote may exclude controls, filters, flushing, upgraded gas pipework or the work required to achieve the boiler’s advertised hot-water performance.

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Frequently Asked Questions

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Are Navien boilers good boilers?

Navien offers compact and higher-performance gas boilers with stainless-steel heat exchangers, smart controls and warranties of between five and twelve years, depending on the model. The finished system will also depend on correct selection, installation and commissioning.

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How much does a Navien boiler cost?

Current advertised installed prices start at approximately £1,840 for an NCB300 and £2,249 for an NCB500. More complex work, boiler relocation and higher-performance models will cost more.

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Which Navien combi boiler do I need?

The NCB300 may suit smaller properties, while the NCB500 ON is aimed more towards modern family homes. The NCB700 ON is intended for properties with particularly high hot-water requirements. The final decision should follow heat-loss and water-flow testing.

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Can a Navien combi supply several showers?

Selected models are specifically designed for higher hot-water demand. Navien states that the NCB700 ON can supply three bathrooms simultaneously, but the property must have sufficient incoming pressure, flow and suitable distribution pipework.

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What is the difference between NCB300 and NCB500 ON?

The NCB300 is the entry-level range and carries a five-year warranty. The NCB500 ON includes enhanced hot-water controls, higher available flow, smart-control features and a ten-year warranty.

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What is the difference between NCB500 ON and NCB700 ON?

The NCB700 ON has a higher maximum hot-water output, integral domestic hot-water recirculation, flow rates up to 22 litres per minute and a twelve-year warranty. The NCB500 ON is a more compact all-rounder for normal family-home requirements.

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Does Navien make system boilers?

Yes. The NCB500 System Boiler is available in 15kW, 18kW, 24kW and 30kW outputs and works with a separate hot-water cylinder.

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Can I replace a regular boiler with a Navien combi?

This is often possible, but the water pressure, flow rate, gas supply, existing pipework and household hot-water demand must be assessed before the cylinder and tanks are removed.

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How long is a Navien boiler warranty?

Current Navien gas boiler warranties range from five years for the NCB300 to twelve years for the NCB700 ON. Registration, correct commissioning and annual servicing are required.

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Who can install a Navien gas boiler?

A Navien gas boiler must be installed and commissioned by a suitably qualified Gas Safe registered engineer.

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Find the Right Navien Boiler for Your Home

 

Choosing the right Navien boiler starts with understanding your property, the existing heating system and the amount of heating and hot water your household requires. APN Boilers can connect you with experienced local heating professionals who can test the water supply, assess the radiators and pipework, recommend a suitable Navien combi or system boiler and provide a clear quotation for the complete installation. Tell us about your property and what you would like to achieve to take the next step towards a warmer and more controllable home.