Warmflow Agentis Boilerhouse Condensing Oil Boiler 15–21kW
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Warmflow Agentis Boilerhouse Condensing Oil Boiler 15–21kW
(Approx. 3-5 working days)


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The Warmflow Agentis Boilerhouse B21 is a floor standing, condensing oil fired boiler designed for installation in boiler houses or garages. It operates on kerosene and is suitable for indoor applications where space and accessibility are key considerations.
This oil boiler delivers a central heating output range of 15–21kW and incorporates a patented stainless steel heat exchanger for improved thermal efficiency. It uses Riello low NOx burner technology to meet current emissions requirements and ensure quiet operation. The boiler is supplied fully wired with a factory fitted burner, thermostat, and condensate trap for straightforward installation.
The B21 supports multiple flue configurations, including conventional and balanced options, and features top-mounted flow and return connections for ease of plumbing. It is ErP A-rated for efficiency and complies with UK and Ireland building regulations for energy performance.
- Output range: 15–21kW for central heating
- Dimensions: 697mm (H) x 395mm (W) x 600mm (D)
- Patented stainless steel heat exchanger for high efficiency
- Riello low NOx burner meets legislative requirements
- Factory fitted condensate trap and thermostat included
| Brand | Warmflow |
|---|---|
| Width | 395 mm |
| Energy Rating | Not Selected |
| Applicable Standards | SEDBUK Band A, OFTEC Approved |
| Connection Size | 1 " |
| Depth | 600 mm |
| Flue Included | No |
| Fuel Type | Kerosene & HVO |
| Heating Energy Rating | A |
| Heat Output Range | 15–21kW |
| Height | 697 mm |
| Heating Output | 21 kW |
| Min Heat Output | 15 |
| Model Name / No | B21 |
| Weight | 114 kg |
| Sold Per | Pallet |
| Colour | Blue |
| Mount Type | Free Standing |
| Hydrogen Ready | No |
| NOx Class | Class 3 |
| Residential Warranty | 2 years parts & labour, 5 years heat exchanger |
| Sound Power Level (dB A): | 52 dB |
| Burner Type | Riello RDB 2.2 |
| Casing Material | Powder-coated steel, blue leather grain finish |
| Condensate Trap | Integrated |
| Flue System | Conventional, low-level, high-level, vertical |
| Frost Protection | Factory fitted frost stat |
| Seasonal Efficiency | 93% |
- Delivery cost will be calculated at checkout once delivery address has been confirmed
- Delivery lead times are an estimate only
- Delivery drivers will always prioritise safety over convenience when offloading materials
- Bagged products such as cement and plaster cannot be returned once opened
- Jumbo bags cannot be returned once delivered
- All other goods may be returned within 3 months with a proof of purchase provided
- Chargeable pallets may be returned for a full refund
- All online pricing is specific to Northern Ireland only. Pricing for our Isle of Man branch may vary.
The Warmflow Agentis Boilerhouse B21 is a floor standing, condensing oil fired boiler designed for installation in boiler houses or garages. It operates on kerosene and is suitable for indoor applications where space and accessibility are key considerations.
This oil boiler delivers a central heating output range of 15–21kW and incorporates a patented stainless steel heat exchanger for improved thermal efficiency. It uses Riello low NOx burner technology to meet current emissions requirements and ensure quiet operation. The boiler is supplied fully wired with a factory fitted burner, thermostat, and condensate trap for straightforward installation.
The B21 supports multiple flue configurations, including conventional and balanced options, and features top-mounted flow and return connections for ease of plumbing. It is ErP A-rated for efficiency and complies with UK and Ireland building regulations for energy performance.
- Output range: 15–21kW for central heating
- Dimensions: 697mm (H) x 395mm (W) x 600mm (D)
- Patented stainless steel heat exchanger for high efficiency
- Riello low NOx burner meets legislative requirements
- Factory fitted condensate trap and thermostat included
| Brand | Warmflow |
|---|---|
| Width | 395 mm |
| Energy Rating | Not Selected |
| Applicable Standards | SEDBUK Band A, OFTEC Approved |
| Connection Size | 1 " |
| Depth | 600 mm |
| Flue Included | No |
| Fuel Type | Kerosene & HVO |
| Heating Energy Rating | A |
| Heat Output Range | 15–21kW |
| Height | 697 mm |
| Heating Output | 21 kW |
| Min Heat Output | 15 |
| Model Name / No | B21 |
| Weight | 114 kg |
| Sold Per | Pallet |
| Colour | Blue |
| Mount Type | Free Standing |
| Hydrogen Ready | No |
| NOx Class | Class 3 |
| Residential Warranty | 2 years parts & labour, 5 years heat exchanger |
| Sound Power Level (dB A): | 52 dB |
| Burner Type | Riello RDB 2.2 |
| Casing Material | Powder-coated steel, blue leather grain finish |
| Condensate Trap | Integrated |
| Flue System | Conventional, low-level, high-level, vertical |
| Frost Protection | Factory fitted frost stat |
| Seasonal Efficiency | 93% |
- Delivery cost will be calculated at checkout once delivery address has been confirmed
- Delivery lead times are an estimate only
- Delivery drivers will always prioritise safety over convenience when offloading materials
- Bagged products such as cement and plaster cannot be returned once opened
- Jumbo bags cannot be returned once delivered
- All other goods may be returned within 3 months with a proof of purchase provided
- Chargeable pallets may be returned for a full refund
- All online pricing is specific to Northern Ireland only. Pricing for our Isle of Man branch may vary.


