Danfoss BFP21 L3 vs BFP21 R3: Which Fuel Pump Fits Your Burner?

Raj Kothari
Aug 26
8 min read

Danfoss BFP21 L3 and BFP21 R3 fuel pumps may look similar, but they do not rotate in the same direction. Selecting the wrong version can create mounting, coupling, piping and fuel-delivery problems.

The choice is also more detailed than simply selecting L3 or R3. A complete Danfoss BFP21 pump designation can identify:

Pump rotation
Capacity group
Nozzle or pressure-outlet position
Coil voltage
One-pipe or two-pipe configuration
Standard or service version
Biofuel compatibility
Exact Danfoss part number

For this reason, the complete product label must be checked before replacing a Danfoss oil pump.

This guide explains the differences between BFP21 L3 and BFP21 R3 and how to identify the correct pump for a compatible oil burner.

You can also browse the available models in our Danfoss fuel pump category.

Quick BFP21 L3 vs BFP21 R3 comparison

Feature	Danfoss BFP21 L3	Danfoss BFP21 R3
Pump rotation	Left or counter-clockwise	Right or clockwise
Viewing position	Determined while looking from the shaft end	Determined while looking from the shaft end
Capacity group	Size 3	Size 3
Reference capacity	24 L/h	24 L/h
Pump stages	One stage	One stage
Pressure regulation	Built-in	Built-in
Solenoid cut-off	Included on BFP21	Included on BFP21
Filter	Cartridge filter	Cartridge filter
Nozzle outlet	Can be left, right or L+R depending on the complete model	Can be left, right or L+R depending on the complete model
Selection requirement	Match full code, rotation, outlet, voltage and piping	Match full code, rotation, outlet, voltage and piping

The main family-level difference is rotation. However, the exact part number remains essential because different L3 and R3 variants can have different outlets, coil voltages and piping configurations.

What does a Danfoss BFP21 fuel pump do?

A Danfoss BFP21 pump draws fuel from the storage tank, passes it through the built-in filter, increases the pressure and supplies fuel to the burner nozzle.

The pressure regulator maintains the selected fuel pressure. When voltage reaches the normally closed solenoid valve, the valve opens and allows fuel to reach the nozzle outlet. When the burner stops, power to the valve is removed and the fuel supply is cut off.

A correctly selected oil pump supports:

Stable fuel pressure
Reliable burner ignition
Consistent nozzle atomisation
Immediate fuel cut-off
Stable combustion
Safe burner start-up and shutdown

Pump selection must be based on the burner manufacturer’s specification and the complete code on the existing pump.

Understanding the Danfoss BFP21 model name

A designation such as BFP21 L3L contains more information than it first appears to.

BFP

BFP identifies the Danfoss burner fuel-pump series.

2

The number 2 indicates a cartridge filter and front pressure adjustment.

1

The number 1 indicates that the pump has one solenoid valve. This provides the cut-off function used to stop fuel flow to the nozzle when the burner shuts down.

L or R

The letter immediately following 21 identifies rotation:

L: counter-clockwise or left rotation
R: clockwise or right rotation

Danfoss determines rotation while viewing the pump from the shaft end.

3

The number 3 identifies the 24 L/h capacity group. Danfoss specifies this reference capacity at 2800 rpm, 10 bar and 4.3 cSt viscosity.

Final L or R

A final letter identifies the nozzle or pressure-outlet position:

L: left-hand nozzle outlet
R: right-hand nozzle outlet
L+R: service configuration with outlet options on both sides

This means BFP21 L3L and BFP21 L3R have the same left rotation but different nozzle-outlet positions.

Danfoss BFP21 L3 fuel pump

The BFP21 L3 family uses left or counter-clockwise rotation when viewed from the shaft end.

Common configurations include:

BFP21 L3L: left rotation with left nozzle outlet
BFP21 L3R: left rotation with right nozzle outlet
BFP21 L3 L+R: left rotation with service outlet options

The exact configuration depends on the Danfoss part number.

Example: Danfoss 071N0250

Danfoss code 071N0250 identifies a BFP21 L3L pump with:

Left rotation
Left nozzle or pressure outlet
24 L/h reference capacity
One-stage construction
Normally closed solenoid cut-off
Cartridge filter
220–230 V AC coil
Kerosene and light-oil compatibility

Therefore, 071N0250 should not be described as a BFP21 R3 pump.

When should you select BFP21 L3?

Select an L3 model when:

The existing pump label specifies BFP21 L3
The burner motor requires counter-clockwise pump rotation
The pump coupling and burner assembly match left rotation
The selected part number provides the correct outlet and voltage
The burner manufacturer specifies the same configuration

Do not select it only because the inlet and outlet connections appear to fit.

Danfoss BFP21 R3 fuel pump

The BFP21 R3 family uses right or clockwise rotation when viewed from the shaft end.

Possible configurations include:

BFP21 R3L: right rotation with left nozzle outlet
BFP21 R3R: right rotation with right nozzle outlet
BFP21 R3 L+R: right rotation with service outlet options

As with the L3 family, the complete part number determines the actual configuration.

Danfoss lists multiple R3 codes for different outlets, voltages, piping arrangements and service applications. For example, the current BFP 20/21 ordering data identifies 071N1248 as a 24 L/h R3 configuration with right rotation and a right-hand nozzle outlet.

Service references may use other codes. The number on the old pump must therefore be matched instead of assuming that every BFP21 R3 is identical.

When should you select BFP21 R3?

Select an R3 model when:

The existing pump specifies BFP21 R3
The burner motor requires clockwise pump rotation
The coupling and burner design match right rotation
The nozzle outlet is in the correct position
The part number matches the required voltage and piping arrangement

A BFP21 R3 should not be used in place of an L3 unless the burner manufacturer or a qualified technician confirms the complete conversion.

The most important difference: pump rotation

Rotation is the first major difference between BFP21 L3 and BFP21 R3.

BFP21 L3 rotates counter-clockwise.
BFP21 R3 rotates clockwise.
Both directions are identified while viewing the shaft end of the pump.

Checking from the wrong side can lead to an incorrect identification. A technician should compare the direction marking on the old pump and confirm how the pump is driven by the burner motor.

Installing the wrong rotation can prevent the pump from drawing and pressurising fuel correctly.

Rotation and outlet direction are not the same

One common mistake is treating L3 as meaning “left outlet” and R3 as meaning “right outlet.”

That is incorrect.

The L or R immediately before the number 3 identifies rotation. A final L or R identifies the nozzle outlet.

Examples:

BFP21 L3L: left rotation and left outlet
BFP21 L3R: left rotation and right outlet
BFP21 R3L: right rotation and left outlet
BFP21 R3R: right rotation and right outlet

A service model may show L+R, indicating outlet options on both sides. Always confirm which connection is used and how the unused connection must be closed.

Technical characteristics shared by the BFP21 size-3 family

Exact specifications vary by code, but standard BFP21 size-3 pumps commonly share these characteristics:

Fuel-pump series: BFP21
Capacity group: size 3
Reference capacity: 24 L/h
Pump stages: one
General pressure range: 7–20 bar, subject to fuel and variant limits
Typical factory pressure setting: 10 bar
Speed range: approximately 2400–3450 rpm
Filter: 200-micron cartridge filter
Filter area: 11 cm²
Solenoid function: normally closed fuel cut-off
Typical coil supply: 230 V, 50/60 Hz
Enclosure: IP40
Fuel: kerosene, light oil or approved biofuel blends depending on the exact version

Other coil voltages and product configurations exist. The values printed on the individual pump label must take priority over general series information.

One-pipe vs two-pipe operation

Danfoss BFP20/21 pumps can be used in one-pipe or two-pipe systems when the exact product and conversion arrangement permit it.

One-pipe system

In a one-pipe system, fuel is drawn from the tank through the suction line. Excess fuel is returned internally within the pump.

Two-pipe system

A two-pipe system has both suction and return lines. Excess fuel is returned to the tank through the return connection.

The changeover screw and return connection must be configured correctly. An incorrect one-pipe or two-pipe setup can cause poor priming, pressure problems or leakage.

Do not change the piping configuration without following the official Danfoss instructions and confirming that the exact pump code supports the required setup.

Standard pumps vs service pumps

Danfoss offers standard and service versions of BFP21 L3 and R3 pumps.

Service models may provide:

L+R nozzle-outlet options
A replacement for multiple older part numbers
A different delivered piping configuration
Additional conversion components
Updated biofuel compatibility

For example, Danfoss service references include L3 and R3 models with different service codes. This does not mean that every standard pump can be replaced without checking its configuration.

When replacing an older pump, confirm:

Old code number
New service code
Delivered one-pipe or two-pipe setup
Required changeover parts
Coil voltage
Rotation
Outlet position
Fuel compatibility

How to choose between BFP21 L3 and BFP21 R3

1. Read the existing label

Record the complete Danfoss code number and model designation. Do not rely on a handwritten note, invoice description or visual similarity.

2. Confirm rotation from the shaft end

Identify whether the existing pump rotates left or right while viewing it from the shaft end.

3. Check the nozzle outlet

Determine whether the nozzle or pressure outlet is on the left, right or both sides.

4. Verify the coil voltage

Many BFP21 pumps use a 220–230 V AC coil, but other voltages exist. Match the value shown on the old pump.

5. Confirm piping configuration

Check whether the existing installation uses one-pipe or two-pipe operation and how the return connection is configured.

6. Match capacity and pressure

Confirm that the burner requires the size-3 capacity group and that the operating pressure is within the permitted range for the fuel being used.

7. Check fuel compatibility

Confirm whether the system uses kerosene, standard light fuel oil or a biofuel blend. Compatibility can differ between standard and Bio-ready variants.

8. Check mounting and shaft details

Compare the shaft diameter, flats, mounting neck, coupling and available space.

9. Share photographs before ordering

If the label is unclear, provide photographs of:

The complete pump label
Shaft and coupling
Nozzle outlet
Suction and return connections
Solenoid coil
Burner nameplate
Existing piping

These details help reduce replacement errors.

Common mistakes when ordering a Danfoss BFP21 pump

Treating 071N0250 as an R3 pump

Danfoss identifies 071N0250 as BFP21 L3L. It has left rotation and a left outlet.

Checking rotation from the wrong side

Danfoss determines rotation while looking from the shaft end.

Ignoring the final outlet letter

L3L and L3R share the same rotation but have different nozzle outlets.

Matching only the pump appearance

Several BFP21 variants use similar housings but have different codes and specifications.

Assuming all BFP21 pumps use 230 V

Other voltages exist. Always check the coil label.

Ignoring one-pipe or two-pipe setup

The delivered configuration and changeover arrangement must match the installation.

Assuming every fuel blend is compatible

Biofuel compatibility depends on the exact pump version.

Signs that the burner fuel pump needs inspection

Common symptoms include:

Burner fails to prime
Unstable nozzle pressure
Repeated burner lockout
Unusual pump noise
Fuel leakage
Delayed ignition
Poor flame stability
Pump shaft or coupling damage
Solenoid valve not opening
Filter blockage

These symptoms do not automatically prove that the pump must be replaced. Similar problems can be caused by air entering the suction line, a blocked filter, an incorrect nozzle, low fuel level, damaged coupling, faulty solenoid coil or incorrect pressure adjustment.

Testing and pressure measurement should be performed by a qualified burner technician.

Frequently asked questions

What is the difference between Danfoss BFP21 L3 and R3?

The main difference is rotation. L3 has counter-clockwise rotation and R3 has clockwise rotation when viewed from the shaft end.

Does L3 always have a left nozzle outlet?

No. L3 identifies rotation. The final letter identifies the outlet. BFP21 L3L has a left outlet, while BFP21 L3R has a right outlet.

Is Danfoss 071N0250 an L3 or R3 pump?

071N0250 is a BFP21 L3L pump with left rotation and a left nozzle outlet. It should not be labelled BFP21 R3.

Can BFP21 L3 replace BFP21 R3?

Not directly. Their rotation differs. Any conversion must be approved for the burner and must account for coupling, outlet, piping, voltage and mounting.

What does the number 3 mean?

The number 3 identifies the 24 L/h capacity group at the Danfoss reference conditions.

Can a BFP21 pump be used in a one-pipe system?

Certain configurations support one-pipe operation or can be converted according to Danfoss instructions. Check the exact part number and delivered setup.

Are all BFP21 pumps suitable for biofuel?

No. Biofuel-blend compatibility varies by product version. Confirm the exact code and fuel specification.

What information should I send before buying?

Send the full model, part number, pump photo, burner model, rotation, outlet position, coil voltage, fuel type and piping configuration.

Find the correct Danfoss BFP21 fuel pump

Mahalaxmi Sales supplies Danfoss oil pumps and burner fuel pumps from Ahmedabad to customers across India.

Browse the Danfoss fuel pump category to compare available BFP and RSA pump models.

For BFP21 L3 or BFP21 R3 matching assistance, share a clear photograph of the existing pump label, burner nameplate, shaft, outlet and piping arrangement. Installation, pressure adjustment and commissioning should be completed by a qualified burner technician.