The Navien LCB700 21kW RS Internal Regular Oil Boiler is a high-efficiency condensing oil boiler designed for internal installation in domestic heating systems.
Part of Navien's innovative LCB700 range, the LCB700-21RS combines advanced blue flame combustion technology, a durable stainless-steel heat exchanger and flexible installation options to provide efficient, dependable oil-fired central heating.
With a two-stage heat output of 16kW / 21kW at 80/60°C and up to 23.0kW at 50/30°C, this model is designed for properties requiring a compact regular oil boiler with excellent efficiency and low emissions.
Key Features
Navien LCB700 internal regular oil boiler
Model: LCB700-21RS
Maximum heat output: 21kW
Two-stage 16kW / 21kW heat output at 80/60°C
Up to 23.0kW output at 50/30°C
Condensing blue flame oil boiler technology
ErP A-rated boiler
93% ErP efficiency
Can achieve A+ system efficiency when combined with qualifying Navien Smart Plus controls
HVO compatible
Stainless-steel heat exchanger
Ultra-low NOx combustion technology
57.2mg/kWh NOx emission rate
Compact internal design
Text-driven integral display
Displays boiler operating and fuel consumption information
3-zone ready when used with Navien Smart Plus control pack
Flexible pipework arrangements
Combined PRV / condensate drainage design
60/100mm coaxial plastic flue system
Maximum horizontal flue length up to 20 metres
Maximum vertical flue length up to 21 metres
10-year parts and labour warranty as standard, subject to Navien terms
Technical Specification
Brand: Navien
Range: LCB700
Model: LCB700-21RS
Product Type: Internal Regular Oil Boiler
Boiler Type: Condensing Regular / Heat Only Boiler
Installation Location: Internal
Fuel Type: Heating Oil / Kerosene
HVO Compatible: Yes
Heat Input Stage 1 / Stage 2: 17kW / 22kW
Heat Output at 80/60°C: 16kW / 21kW
Maximum Heat Output at 50/30°C: 23.0kW
ErP Energy Rating: A
ErP Efficiency: 93%
Potential System Rating: Up to A+ with qualifying Smart Plus control configuration
NOx Emissions: 57.2mg/kWh
Heat Exchanger: Stainless Steel
Flue Type: Coaxial Plastic
Flue Size: 60/100mm
Maximum Horizontal Flue Length: 20m
Maximum Vertical Flue Length: 21m
90° Flue Elbow Equivalent: 1.3m
Central Heating Flow Connection: 22mm
Central Heating Return Connection: 22mm
Oil Supply: 1/4" BSP
Condensate Connection: 21.5mm minimum
Dimensions: 470mm W x 600mm D x 860mm H
Net Weight: 58kg
Control Display: Integral text-driven display
Smart Control Compatibility: Navien Smart Plus
Heating Zones: Up to 3 zones with compatible Smart Plus controls
Warranty: 10-year parts and labour warranty, subject to manufacturer terms
High Efficiency Blue Flame Technology
The Navien LCB700 incorporates advanced blue flame combustion technology designed to deliver efficient oil combustion while keeping NOx emissions low.
The LCB700-21RS achieves an ErP A rating with 93% efficiency. When incorporated into a qualifying heating system using Navien Smart Plus controls, the system can achieve an A+ rating.
21kW Two-Stage Heating Performance
The LCB700-21RS operates at two heating stages, providing approximately 16kW and 21kW output at 80/60°C. At lower-temperature condensing conditions of 50/30°C, maximum output increases to approximately 23.0kW.
This two-stage design allows the boiler to better respond to changing heating demand compared with a simple fixed-output appliance.
HVO Compatible
Navien lists the LCB700 range as HVO compatible, helping provide greater flexibility as the heating industry transitions towards lower-carbon liquid fuel alternatives.
Fuel suitability, burner setup and any conversion or commissioning requirements should always be confirmed by a qualified oil heating engineer and carried out in accordance with current Navien instructions.
Stainless-Steel Heat Exchanger
The LCB700 features a durable stainless-steel heat exchanger designed to provide long-term performance and efficiency in a condensing oil boiler application.
Flexible Flue Installation
The Navien LCB700 uses a 60/100mm coaxial plastic flue system and offers unusually long flue capabilities for flexible installation.
Maximum horizontal flue length: up to 20m
Maximum vertical flue length: up to 21m
90° elbow equivalent deduction: approximately 1.3m
Actual permitted flue length depends on the complete approved flue arrangement, number of bends and Navien installation instructions.
Smart Plus Controls
The LCB700 is compatible with Navien's Smart Plus control system. When correctly configured, Smart Plus can provide multi-zone heating control, with the LCB700 capable of supporting up to three heating zones.
A qualifying Smart Plus control configuration can also increase the overall system energy rating from ErP A to ErP A+.
Regular Boiler Installation
The LCB700-21RS is a regular / heat-only boiler. It does not provide instantaneous domestic hot water in the same way as a combination boiler.
Where domestic hot water is required, the boiler is typically incorporated into a heating system using a separate hot water cylinder and the necessary external system components and controls.
10-Year Warranty
Navien currently advertises the LCB700 range with a 10-year parts and labour warranty as standard, subject to installation, commissioning, registration, servicing and all applicable Navien warranty terms.
Important Product Information
This product is the Navien LCB700-21RS 21kW Internal Regular Oil Boiler.
Do not confuse this model with the LCB700-21LS System Boiler, LCB700-21LC Combi Boiler or the external LCB700-21RSX version.
Flue kit, hot water cylinder, heating controls, system components, oil line components, filters, valves, chemicals and installation accessories are not included unless specifically stated elsewhere in the listing.
Professional Installation Required
This oil-fired boiler must be installed and commissioned by a suitably qualified oil heating engineer. In the UK, installation by an OFTEC registered technician is recommended.
The installer must confirm boiler sizing, system design, oil supply, fuel type, flue arrangement, condensate disposal, heating controls and combustion settings before commissioning.
Delivery Times
All our deliveries are made by some of the countries most trusted couriers, including Royal Mail, PacelForce, DHL , Fastway Curriers
For most larger sized deliveries, you will receive a call from the courier an hour before the scheduled delivery time.
Free Delivery
Free delivery when you spend £150+ on all our stocked items, up to the maximum 20kg in weight (UK & Ireland Only) To be eligible for this service, you must place your order before 1pm on the previous day.
Delivery Drop Off
It is important to note that we use external shipping couriers. They are responsible for delivering the item(s) to the kerb-side. They are not responsible for delivering items into your home*.
*Please note, for large orders we advise that you seek assistance from friends or neighbours to assist with moving your order, as often the driver will not be able to assist you. Some items may be delivered on a pallet. It is your responsibility to dispose of the pallet, however, we recommend keeping it for the first 14 days in case you need to return your item(s).
Failed Deliveries
In the unlikely event that delivery is attempted when you are not at home, we will contact you by phone and re-book another time that suits you. Please note, there may be a re-delivery charge added at our discretion, which will be reviewed on a case by case basis.
Direct Deliveries from Distribution Centers
To help you receive your items as quickly as possible, parts of your order may be dispatched directly from a distribution center (Ie) Amazon. If this is the case, you will be contacted directly by them to arrange delivery for the products concerned. Please note, these items will arrive at a different time to products dispatched from our head warehouse. Some distribution centers may take between 2-3 days to deliver items.
Non-Stocked Items
Some items are ordered into our warehouse especially for your orders. This means there may be additional lead times on your order arriving. The estimated delivery time for non-stocked items is 5-7 working days.
For orders that contain a mixture of stock and non-stock items, excluding items delivered directly from distribution centers, we will deliver all items together. We will make you aware of this when we phone or email you to confirm the delivery date. You will be given the option to receive them separately as well, however there may be additional shipping charges.
Shipping Rates
All Orders to the UK & Ireland *ONLY*up to 20kg £150+ is Free
Pallet Rates are priced on application and order... delivery lead times will also vary based on post code.
Returns
Returns are subject too a 50% re-stocking charge.
- Items installed/fitted without professional understanding IE Oftec/SafeGas Registered Installer certificates, invalidate any warranty of said item bought.. This is however is at the companies discretion.
- All products must be inspected within 24hrs. Goods are non-returnable after this period.
To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.
Several types of goods are exempt from being returned. Goods including but not limited to printed circuit boards, control boxes, chemicals, hazardous materials, flammable liquids or gases. Please ask if you are unsure if you can return your goods.
Some items are not returnable such as PCB Boards and Boilers if they are opened, There also will be a 25% Handling fee for All Items if accepted for return.
To complete your return, we require a receipt or proof of purchase.
Please do not send your purchase back to the manufacturer unless otherwise instructed by Spares Direct.
There are certain situations where only partial refunds are granted (if applicable) Any item not in its original condition, is damaged or missing parts for reasons not due to manufacturer / supplier error Any item that is returned more than 30 days after delivery
Refunds (if applicable) Once your return is received and inspected, we will send you an email to notify you that we have received your returned item. We will also notify you of the approval or rejection of your refund. If you are approved, then your refund will be processed, and a credit will automatically be applied to your credit card or original method of payment, within a certain amount of days.
Late or missing refunds (if applicable) If you haven’t received a refund yet, first check your bank account again. Then contact your credit card company, it may take some time before your refund is officially posted. Next contact your bank. There is often some processing time before a refund is posted. If you’ve done all of this and you still have not received your refund, please contact us at info@sparesdirect.ie
Sale items (if applicable) Only regular priced items may be refunded, unfortunately sale items cannot be refunded.
Exchanges (if applicable) We only replace items if they are defective or damaged. If you need to exchange it for the same item, send us an email at info@sparesdirect.ie and send your item to: Unit 5 Dargan Industrial Park, 62 Dargan Crescent, Belfast BT3 9JP.
Unwanted goods or Failed deliveries of items bought If for any reason you order from us and the item has been shipped, but you no longer wish to have the item, the goods should be returned to us at the consumers cost. The price of goods will be refunded upon delivery/inspection (please note carriage cost will NOT be refunded. This also applies to missed deliveries/collection of goods from currier depot.
Shipping To return your product, you should mail your product to: Unit 5 Dargan Industrial Park, 62 Dargan Crescent, Belfast BT3 9JP.
You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund.
Depending on where you live, the time it may take for your exchanged product to reach you, may vary.
If you are shipping an item over £50, you should consider using a trackable shipping service or purchasing shipping insurance. We don’t guarantee that we will receive your returned item.
The Navien LCB700 21kW RS Internal Regular Oil Boiler is a high-efficiency condensing oil boiler designed for internal installation in domestic heating systems.
Part of Navien's innovative LCB700 range, the LCB700-21RS combines advanced blue flame combustion technology, a durable stainless-steel heat exchanger and flexible installation options to provide efficient, dependable oil-fired central heating.
With a two-stage heat output of 16kW / 21kW at 80/60°C and up to 23.0kW at 50/30°C, this model is designed for properties requiring a compact regular oil boiler with excellent efficiency and low emissions.
Key Features
Navien LCB700 internal regular oil boiler
Model: LCB700-21RS
Maximum heat output: 21kW
Two-stage 16kW / 21kW heat output at 80/60°C
Up to 23.0kW output at 50/30°C
Condensing blue flame oil boiler technology
ErP A-rated boiler
93% ErP efficiency
Can achieve A+ system efficiency when combined with qualifying Navien Smart Plus controls
HVO compatible
Stainless-steel heat exchanger
Ultra-low NOx combustion technology
57.2mg/kWh NOx emission rate
Compact internal design
Text-driven integral display
Displays boiler operating and fuel consumption information
3-zone ready when used with Navien Smart Plus control pack
Flexible pipework arrangements
Combined PRV / condensate drainage design
60/100mm coaxial plastic flue system
Maximum horizontal flue length up to 20 metres
Maximum vertical flue length up to 21 metres
10-year parts and labour warranty as standard, subject to Navien terms
Technical Specification
Brand: Navien
Range: LCB700
Model: LCB700-21RS
Product Type: Internal Regular Oil Boiler
Boiler Type: Condensing Regular / Heat Only Boiler
Installation Location: Internal
Fuel Type: Heating Oil / Kerosene
HVO Compatible: Yes
Heat Input Stage 1 / Stage 2: 17kW / 22kW
Heat Output at 80/60°C: 16kW / 21kW
Maximum Heat Output at 50/30°C: 23.0kW
ErP Energy Rating: A
ErP Efficiency: 93%
Potential System Rating: Up to A+ with qualifying Smart Plus control configuration
NOx Emissions: 57.2mg/kWh
Heat Exchanger: Stainless Steel
Flue Type: Coaxial Plastic
Flue Size: 60/100mm
Maximum Horizontal Flue Length: 20m
Maximum Vertical Flue Length: 21m
90° Flue Elbow Equivalent: 1.3m
Central Heating Flow Connection: 22mm
Central Heating Return Connection: 22mm
Oil Supply: 1/4" BSP
Condensate Connection: 21.5mm minimum
Dimensions: 470mm W x 600mm D x 860mm H
Net Weight: 58kg
Control Display: Integral text-driven display
Smart Control Compatibility: Navien Smart Plus
Heating Zones: Up to 3 zones with compatible Smart Plus controls
Warranty: 10-year parts and labour warranty, subject to manufacturer terms
High Efficiency Blue Flame Technology
The Navien LCB700 incorporates advanced blue flame combustion technology designed to deliver efficient oil combustion while keeping NOx emissions low.
The LCB700-21RS achieves an ErP A rating with 93% efficiency. When incorporated into a qualifying heating system using Navien Smart Plus controls, the system can achieve an A+ rating.
21kW Two-Stage Heating Performance
The LCB700-21RS operates at two heating stages, providing approximately 16kW and 21kW output at 80/60°C. At lower-temperature condensing conditions of 50/30°C, maximum output increases to approximately 23.0kW.
This two-stage design allows the boiler to better respond to changing heating demand compared with a simple fixed-output appliance.
HVO Compatible
Navien lists the LCB700 range as HVO compatible, helping provide greater flexibility as the heating industry transitions towards lower-carbon liquid fuel alternatives.
Fuel suitability, burner setup and any conversion or commissioning requirements should always be confirmed by a qualified oil heating engineer and carried out in accordance with current Navien instructions.
Stainless-Steel Heat Exchanger
The LCB700 features a durable stainless-steel heat exchanger designed to provide long-term performance and efficiency in a condensing oil boiler application.
Flexible Flue Installation
The Navien LCB700 uses a 60/100mm coaxial plastic flue system and offers unusually long flue capabilities for flexible installation.
Maximum horizontal flue length: up to 20m
Maximum vertical flue length: up to 21m
90° elbow equivalent deduction: approximately 1.3m
Actual permitted flue length depends on the complete approved flue arrangement, number of bends and Navien installation instructions.
Smart Plus Controls
The LCB700 is compatible with Navien's Smart Plus control system. When correctly configured, Smart Plus can provide multi-zone heating control, with the LCB700 capable of supporting up to three heating zones.
A qualifying Smart Plus control configuration can also increase the overall system energy rating from ErP A to ErP A+.
Regular Boiler Installation
The LCB700-21RS is a regular / heat-only boiler. It does not provide instantaneous domestic hot water in the same way as a combination boiler.
Where domestic hot water is required, the boiler is typically incorporated into a heating system using a separate hot water cylinder and the necessary external system components and controls.
10-Year Warranty
Navien currently advertises the LCB700 range with a 10-year parts and labour warranty as standard, subject to installation, commissioning, registration, servicing and all applicable Navien warranty terms.
Important Product Information
This product is the Navien LCB700-21RS 21kW Internal Regular Oil Boiler.
Do not confuse this model with the LCB700-21LS System Boiler, LCB700-21LC Combi Boiler or the external LCB700-21RSX version.
Flue kit, hot water cylinder, heating controls, system components, oil line components, filters, valves, chemicals and installation accessories are not included unless specifically stated elsewhere in the listing.
Professional Installation Required
This oil-fired boiler must be installed and commissioned by a suitably qualified oil heating engineer. In the UK, installation by an OFTEC registered technician is recommended.
The installer must confirm boiler sizing, system design, oil supply, fuel type, flue arrangement, condensate disposal, heating controls and combustion settings before commissioning.
Delivery Times
All our deliveries are made by some of the countries most trusted couriers, including Royal Mail, PacelForce, DHL , Fastway Curriers
For most larger sized deliveries, you will receive a call from the courier an hour before the scheduled delivery time.
Free Delivery
Free delivery when you spend £150+ on all our stocked items, up to the maximum 20kg in weight (UK & Ireland Only) To be eligible for this service, you must place your order before 1pm on the previous day.
Delivery Drop Off
It is important to note that we use external shipping couriers. They are responsible for delivering the item(s) to the kerb-side. They are not responsible for delivering items into your home*.
*Please note, for large orders we advise that you seek assistance from friends or neighbours to assist with moving your order, as often the driver will not be able to assist you. Some items may be delivered on a pallet. It is your responsibility to dispose of the pallet, however, we recommend keeping it for the first 14 days in case you need to return your item(s).
Failed Deliveries
In the unlikely event that delivery is attempted when you are not at home, we will contact you by phone and re-book another time that suits you. Please note, there may be a re-delivery charge added at our discretion, which will be reviewed on a case by case basis.
Direct Deliveries from Distribution Centers
To help you receive your items as quickly as possible, parts of your order may be dispatched directly from a distribution center (Ie) Amazon. If this is the case, you will be contacted directly by them to arrange delivery for the products concerned. Please note, these items will arrive at a different time to products dispatched from our head warehouse. Some distribution centers may take between 2-3 days to deliver items.
Non-Stocked Items
Some items are ordered into our warehouse especially for your orders. This means there may be additional lead times on your order arriving. The estimated delivery time for non-stocked items is 5-7 working days.
For orders that contain a mixture of stock and non-stock items, excluding items delivered directly from distribution centers, we will deliver all items together. We will make you aware of this when we phone or email you to confirm the delivery date. You will be given the option to receive them separately as well, however there may be additional shipping charges.
Shipping Rates
All Orders to the UK & Ireland *ONLY*up to 20kg £150+ is Free
Pallet Rates are priced on application and order... delivery lead times will also vary based on post code.
Returns
Returns are subject too a 50% re-stocking charge.
- Items installed/fitted without professional understanding IE Oftec/SafeGas Registered Installer certificates, invalidate any warranty of said item bought.. This is however is at the companies discretion.
- All products must be inspected within 24hrs. Goods are non-returnable after this period.
To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.
Several types of goods are exempt from being returned. Goods including but not limited to printed circuit boards, control boxes, chemicals, hazardous materials, flammable liquids or gases. Please ask if you are unsure if you can return your goods.
Some items are not returnable such as PCB Boards and Boilers if they are opened, There also will be a 25% Handling fee for All Items if accepted for return.
To complete your return, we require a receipt or proof of purchase.
Please do not send your purchase back to the manufacturer unless otherwise instructed by Spares Direct.
There are certain situations where only partial refunds are granted (if applicable) Any item not in its original condition, is damaged or missing parts for reasons not due to manufacturer / supplier error Any item that is returned more than 30 days after delivery
Refunds (if applicable) Once your return is received and inspected, we will send you an email to notify you that we have received your returned item. We will also notify you of the approval or rejection of your refund. If you are approved, then your refund will be processed, and a credit will automatically be applied to your credit card or original method of payment, within a certain amount of days.
Late or missing refunds (if applicable) If you haven’t received a refund yet, first check your bank account again. Then contact your credit card company, it may take some time before your refund is officially posted. Next contact your bank. There is often some processing time before a refund is posted. If you’ve done all of this and you still have not received your refund, please contact us at info@sparesdirect.ie
Sale items (if applicable) Only regular priced items may be refunded, unfortunately sale items cannot be refunded.
Exchanges (if applicable) We only replace items if they are defective or damaged. If you need to exchange it for the same item, send us an email at info@sparesdirect.ie and send your item to: Unit 5 Dargan Industrial Park, 62 Dargan Crescent, Belfast BT3 9JP.
Unwanted goods or Failed deliveries of items bought If for any reason you order from us and the item has been shipped, but you no longer wish to have the item, the goods should be returned to us at the consumers cost. The price of goods will be refunded upon delivery/inspection (please note carriage cost will NOT be refunded. This also applies to missed deliveries/collection of goods from currier depot.
Shipping To return your product, you should mail your product to: Unit 5 Dargan Industrial Park, 62 Dargan Crescent, Belfast BT3 9JP.
You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund.
Depending on where you live, the time it may take for your exchanged product to reach you, may vary.
If you are shipping an item over £50, you should consider using a trackable shipping service or purchasing shipping insurance. We don’t guarantee that we will receive your returned item.
Rückerstattungsrichtlinien
Returns
Returns are subject too a 50% re-stocking charge.
- Items installed/fitted without professional understanding IE Oftec/SafeGas Registered Installer certificates, invalidate any warranty of said item bought.. This is however is at the companies discretion.
- All products must be inspected within 24hrs. Goods are non-returnable after this period.
To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.
Several types of goods are exempt from being returned. Goods including but not limited to printed circuit boards, control boxes, chemicals, hazardous materials, flammable liquids or gases. Please ask if you are unsure if you can return your goods.
Some items are not returnable such as PCB Boards and Boilers if they are opened, There also will be a 25% Handling fee for All Items if accepted for return.
To complete your return, we require a receipt or proof of purchase.
Please do not send your purchase back to the manufacturer unless otherwise instructed by Spares Direct.
There are certain situations where only partial refunds are granted (if applicable) Any item not in its original condition, is damaged or missing parts for reasons not due to manufacturer / supplier error Any item that is returned more than 30 days after delivery
Refunds (if applicable) Once your return is received and inspected, we will send you an email to notify you that we have received your returned item. We will also notify you of the approval or rejection of your refund. If you are approved, then your refund will be processed, and a credit will automatically be applied to your credit card or original method of payment, within a certain amount of days.
Late or missing refunds (if applicable) If you haven’t received a refund yet, first check your bank account again. Then contact your credit card company, it may take some time before your refund is officially posted. Next contact your bank. There is often some processing time before a refund is posted. If you’ve done all of this and you still have not received your refund, please contact us at info@sparesdirect.ie
Sale items (if applicable) Only regular priced items may be refunded, unfortunately sale items cannot be refunded.
Exchanges (if applicable) We only replace items if they are defective or damaged. If you need to exchange it for the same item, send us an email at info@sparesdirect.ie and send your item to: Unit 5 Dargan Industrial Park, 62 Dargan Crescent, Belfast BT3 9JP.
Unwanted goods or Failed deliveries of items bought If for any reason you order from us and the item has been shipped, but you no longer wish to have the item, the goods should be returned to us at the consumers cost. The price of goods will be refunded upon delivery/inspection (please note carriage cost will NOT be refunded. This also applies to missed deliveries/collection of goods from currier depot.
Shipping To return your product, you should mail your product to: Unit 5 Dargan Industrial Park, 62 Dargan Crescent, Belfast BT3 9JP.
You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable. If you receive a refund, the cost of return shipping will be deducted from your refund.
Depending on where you live, the time it may take for your exchanged product to reach you, may vary.
If you are shipping an item over £50, you should consider using a trackable shipping service or purchasing shipping insurance. We don’t guarantee that we will receive your returned item.
Info@sparesdirect.ie
02895 434 399
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