Franklin Electric BT4 Series Horizontal Multi-Stage Booster Pump

The Franklin Electric BT4 Series Horizontal Multi-Stage Booster Pump is a versatile, high-pressure centrifugal booster pump designed for residential, commercial, and specialized water pressure applications where consistent pressure from 5 GPM to 45 GPM and discharge pressures up to 400 PSI are required. Whether you are boosting pressure from a city main, a private water system, or a low-pressure rural supply, the BT4 Series Horizontal Multi-Stage Booster Pump covers the range from light residential pressure boosting to demanding commercial building applications. At Ken’s Distributing Company, we stock the full BT4 lineup and can help you select the right model, HP, and configuration for your specific pressure and flow requirements.

What Is the Franklin Electric BT4 Series Booster Pump?

The BT4 is Franklin Electric’s horizontal multi-stage centrifugal booster pump series built for applications that need more pressure than flow. The multi-stage design stacks multiple impeller and diffuser assemblies in series along a common shaft, with each stage adding pressure to the water before it passes to the next. The result is a compact pump capable of delivering significantly higher pressures than a single-stage centrifugal pump of the same size.

The BT4 Series covers a flow range from 5 GPM to 45 GPM across three model groups: the 5 to 25 GPM stainless steel models for residential and light commercial use, the 56C pump end models for installations using customer-supplied motors, and the 35 to 45 GPM models with enhanced hydraulics for commercial applications requiring higher flow. All three groups share the high discharge pressure capability, NSF certification for drinking water where applicable, and the Franklin Electric quality that makes the BT4 one of the most widely specified booster pumps in its class.

Kendisco is an authorized Franklin Electric distributor. When you order the BT4 Series through Ken’s Distributing Company, you receive a genuine Franklin Electric product with full manufacturer support and access to genuine replacement parts. Call our team at 303.699.7845 for help selecting the right BT4 model for your application.

BT4 Series Model Groups: Selecting the Right Configuration

The BT4 Series divides into three distinct model groups based on flow range, motor configuration, and installation requirements. Understanding which group your application falls into is the first step in selecting the right BT4 model.

Feature	5 to 25 GPM Stainless Steel Models	56C Pump End Models	35 to 45 GPM Models
Flow Range	5 to 25 GPM	5 to 25 GPM	35 to 45 GPM
Motor Included	Yes	No, customer supplied	Yes
Max Discharge Pressure	400 PSI	270 PSI shut-off	400 PSI
Inlet/Outlet Size	1 inch NPT	1 inch NPT	1.5 inch NPT
Motor Enclosure	ODP square-flange	Customer specified	ODP or TEFC NEMA 56C
NSF Certified	Yes, NSF/ANSI/CAN 372	Yes	Yes
Best Application	Residential, light commercial	Custom motor installations	Commercial buildings, higher flow
Mounting	Horizontal or vertical	Horizontal or vertical	Flexible, 90-degree bracket rotation

Technical Specifications

Specification	5 to 25 GPM Models	35 to 45 GPM Models
Flow Range	5 to 25 GPM	35 to 45 GPM
Max Inlet Pressure	75 PSI	75 PSI
Max Discharge Pressure	400 PSI	400 PSI
Max Fluid Temperature	120 degrees F	120 degrees F
Impeller Material	Acetal	Enhanced hydraulics
Diffuser Material	Modified PPO	Enhanced for higher flow
Shell/Hub/Shaft	300 Series Stainless Steel	Stainless Steel
Seal	Carbon/Ceramic, FKM elastomers, SS hardware	Carbon/Ceramic, FKM elastomers, SS hardware
Inlet/Outlet	1 inch NPT	1.5 inch NPT
Certification	NSF/ANSI/CAN 372	NSF/ANSI/CAN 372

Order Information

5-25 GPM Horizontal Multi-Stage Single Phase Stainless Steel Model

5-25 GPM Horizontal Multi-Stage Three Phase Stainless Steel Model

35-45 GPM Horizontal Multi-Stage Single Phase Stainless Steel Model

35-45 Horizontal Multi-Stage Three Phase Stainless Steel Model

56C Pump End Model

How Multi-Stage Boosting Works

Understanding the multi-stage design of the BT4 explains why it can reach 400 PSI discharge pressure while remaining compact enough for residential and light commercial installations.

A single-stage centrifugal pump has one impeller that accelerates water outward into the volute, converting velocity into pressure. The amount of pressure a single stage can add is limited by the impeller diameter and speed. To get higher pressures without using a much larger and heavier pump, multi-stage pumps add multiple stages in series, each consisting of an impeller and a diffuser.

In the BT4, water enters the first stage impeller, gets accelerated and pressurized, then passes through the stage diffuser into the inlet of the second stage impeller where the process repeats. Each stage adds a pressure increment to the water. By stacking enough stages along the shaft, the BT4 accumulates the pressure boost needed to reach 400 PSI discharge at flow rates between 5 and 45 GPM, depending on model.

The Tri-Seal floating stage system used in the 5 to 25 GPM BT4 models is a patented Franklin Electric design that allows each stage to float axially on the shaft, compensating for thermal expansion during operation and ensuring consistent hydraulic clearances across all stages throughout the operating temperature range. This system is covered under U.S. Patent 7,290,984 and is a key factor in the long service life and consistent performance of the BT4 Series in continuous booster duty.

BT4 Series Features: 5 to 25 GPM Models

• Tri-Seal Floating Stage System: Patented design allowing stages to float axially for consistent hydraulic clearances across thermal expansion cycles. U.S. Patent 7,290,984. A key factor in the long-term performance and service life of the BT4 in continuous booster duty.
• Acetal Impellers and Modified PPO Diffusers: Precision hydraulic components in corrosion-resistant materials that maintain dimensional accuracy and hydraulic performance over a long service life in clean water applications.
• 300 Series Stainless Steel Hub, Shaft, and Shell: All structural and wetted metal components in 300 Series stainless steel for maximum corrosion resistance in drinking water, chemical treatment, and chemically aggressive water supply systems.
• Carbon/Ceramic Mechanical Seal with FKM Elastomers: No-adjustment, no-drip seal with broad chemical compatibility through FKM elastomers. Appropriate for a wide range of water supply and booster applications including systems with mild chemical treatment.
• ODP Square-Flange 2-Compartment Motor: Service-friendly motor design that allows electrical service without pump disassembly. Dual voltage capability for flexibility in different electrical installations. High service factor motors from 1/2 to 3 HP. Three-phase inverter duty rated for variable frequency drive compatibility.
• NSF/ANSI/CAN 372 Certified: Certified for drinking water contact. This certification is required for booster pumps installed in potable water systems in many jurisdictions and is a specification requirement for municipal, commercial, and residential drinking water applications.
• 400 PSI Maximum Discharge Pressure: The highest discharge pressure rating in its class for this flow range. Handles demanding high-pressure booster applications including reverse osmosis pre-pressure boosting, high-rise building water supply, and long distribution line pressure recovery.
• 75 PSI Maximum Inlet Pressure: Accepts city main or private system inlet pressures up to 75 PSI before the boost stage, covering the full range of inlet pressures typical in residential and commercial supply connections.
• Portable Design with Handle: The stainless steel bracket includes a handle for portable installations where the booster pump needs to be moved between service points. 1-inch NPT connections are standard for easy reconnection at different locations.
• Horizontal or Vertical Mounting: Both mounting orientations are supported without modification, giving the installer flexibility to position the pump in the most practical orientation for the available space.

BT4 Series Features: 35 to 45 GPM Models

• Enhanced Hydraulics for Higher Flow: Optimized impeller and diffuser geometry specifically designed for the 35 and 45 GPM flow ratings, delivering better efficiency at these higher flow levels than the smaller model hydraulics scaled up would provide.
• 1.5-Inch NPT Inlet and Outlet: Larger connection size reduces friction loss at the higher flow rates of the 35 to 45 GPM models. Matching the pipe size to the flow rate is critical for maintaining system efficiency at the higher end of the BT4 flow range.
• Bracket Rotation in 90-Degree Increments: The stainless steel bracket can be rotated in 90-degree steps to position the inlet and outlet connections in the most convenient orientation for the installation plumbing. This flexibility reduces the number of fittings needed and simplifies installation in varied commercial mechanical room configurations.
• Multiple Pressure Tapping and Drain Ports: Additional ports for bypass plumbing, pressure gauge connections, and accessory installation. These ports support the control and monitoring configurations typical of commercial booster pump installations.
• Back Pull-Out Motor Design: The motor can be removed for service without disturbing the pump body or the plumbing connections. A significant labor-saving feature in commercial installations where the booster pump is integrated into a fixed plumbing system.
• NEMA 56C Keyed Shaft Motors in ODP and TEFC: Standard NEMA 56C motor frame provides broad motor replacement options from multiple manufacturers. Both open drip-proof and totally enclosed fan-cooled enclosures are available to match the installation environment.
• Robust Stainless Steel Bracket, Shell, and Discharge: Full stainless steel construction on all structural and wetted components for maximum corrosion resistance in commercial water supply environments where the pump may be exposed to aggressive water chemistry or high humidity mechanical rooms.

BT4 Series 56C Pump End Models

The 56C pump end models provide the BT4 hydraulic performance without a motor, allowing the installer to use a customer-supplied 56C frame motor. This configuration is used in applications where a specific motor brand, enclosure type, or efficiency class is required by the project specification, or where an existing motor is available for reuse.

• Standard 56C motor bracket compatible with any NEMA 56C keyed shaft motor
• All stainless steel construction for corrosion resistance throughout the pump end
• Same Tri-Seal floating stage system as the complete BT4 models
• Phenolic and ceramic mechanical seal with FKM elastomers and stainless steel components
• Shut-off pressures up to 270 PSI
• Flow rates between 5 and 25 GPM

If your project specification requires a specific motor or you have an existing compatible motor to reuse, the 56C pump end is the right configuration. Contact Ken’s Distributing at 303.699.7845 to confirm motor compatibility before ordering.

Applications and Industries

The BT4 Series serves a broad range of pressure boosting applications across residential, commercial, and industrial sectors.

• Residential Water Pressure Boosting: Homes with low incoming pressure from municipal supply or private wells use the BT4 to boost pressure to comfortable residential levels for showers, fixtures, and appliances. The 5 to 25 GPM models cover the demand range of most single-family homes. NSF/ANSI/CAN 372 certification confirms safety for drinking water contact.
• Commercial Building Water Supply: Multi-story commercial buildings that cannot rely on municipal supply pressure for upper floors use booster pump systems based on the BT4. The 35 to 45 GPM models with enhanced hydraulics handle the higher demand of commercial building water supply risers.
• Reverse Osmosis Pre-Pressure Boosting: Reverse osmosis systems require inlet pressure above a minimum threshold to function efficiently. The BT4 boosts incoming water pressure to the level required for effective RO membrane operation in commercial water treatment installations.
• Irrigation Pressure Boosting: Drip irrigation systems, micro-sprinkler systems, and sprinkler zones that require more pressure than available from a storage tank or low-pressure supply use the BT4 to deliver consistent operating pressure throughout the system.
• Car Wash and Industrial Wash Systems: Commercial car wash equipment and industrial cleaning systems requiring consistent pressure for effective washing performance use the BT4 for pressure boosting ahead of the wash equipment.
• Pressure Zone Management: Municipal and commercial water distribution systems use pressure booster stations with the BT4 to maintain consistent pressure in zones where the supply pressure drops below service requirements due to elevation or distance from the main.
• Specialized High-Pressure Applications: The 400 PSI maximum discharge pressure of the BT4 makes it suitable for specialized applications requiring higher pressure than standard distribution systems provide, including filtration systems, chemical injection, and process water applications.

BT4 vs. MH Series: Which Multi-Stage Booster Pump Is Right for You?

Franklin Electric offers both the BT4 and MH Series as horizontal multi-stage booster pumps at Kendisco. Here is a direct comparison to help you choose the right one for your application.

Feature	BT4 Series	MH Series
Flow Range	5 to 45 GPM	Residential and light commercial range
Max Discharge Pressure	400 PSI	Moderate pressure range
Stage System	Tri-Seal floating stage (patented)	Standard multi-stage
NSF Certification	Yes, NSF/ANSI/CAN 372	Yes
56C Pump End Option	Yes	No
Max Flow Model	45 GPM	Lower max flow
Best For	High-pressure commercial, RO, specialized	Residential and light commercial boosting
Portable Option	Yes, handle included on small models	Fixed installation

If your application requires the highest pressure output, the widest flow range, the patented Tri-Seal floating stage system, or the 56C pump end option for custom motor installations, the BT4 is the right choice. If your application is standard residential or light commercial pressure boosting within a more moderate pressure and flow range, the MH Series may be a simpler and more cost-effective fit. Call Ken’s Distributing at 303.699.7845 and we will help you decide based on your specific pressure, flow, and installation requirements.

Installation and Compatibility

• Inlet Pressure: Confirm that your incoming supply pressure does not exceed 75 PSI. Inlet pressures above 75 PSI require a pressure reducing valve upstream of the BT4 to protect the pump from overpressure conditions on the inlet side.
• Voltage Selection: Single-phase 5 to 25 GPM models are dual voltage, accepting 115 VAC or 230 VAC. Set the motor to the correct voltage for your supply before first startup. Three-phase models are available for commercial installations and are inverter duty rated for VFD control compatibility.
• Mounting Orientation: Both horizontal and vertical mounting are supported on 5 to 25 GPM models. On 35 to 45 GPM models, the bracket can be rotated in 90-degree increments to align connections with the installation plumbing. Secure the pump to a stable surface to minimize vibration transmission.
• Connection Size: Use 1-inch NPT fittings for 5 to 25 GPM models. Use 1.5-inch NPT fittings for 35 to 45 GPM models. Reducing connection size below the rated port size will create unnecessary restriction and reduce pump performance.
• Pressure Relief: Install a pressure relief valve on the discharge side set to a pressure below the system maximum working pressure to protect against overpressure conditions during pump operation.
• Check Valve: Install a check valve on the discharge side to prevent backflow through the pump when the booster is not running. Some BT4 installations also include a check valve on the inlet to prevent reverse flow from the system back to the supply source.
• Pressure Tank: Many booster applications include a small pressure tank downstream of the BT4 to reduce pump cycling frequency and protect against water hammer in the distribution system. Consult Ken’s Distributing for pressure tank sizing recommendations for your specific BT4 model and application.
• Mechanical Seal: Never run the BT4 dry. The mechanical seal requires liquid contact for lubrication and cooling at all times during operation. Install a low-pressure cutoff switch on the suction side to prevent the pump from running when the inlet supply is interrupted.
• Temperature: Maximum fluid temperature is 120 degrees F. Do not use the BT4 with hot water above this temperature. The acetal impellers and PPO diffusers in the 5 to 25 GPM models are optimized for this temperature range.
• Inline Controls: The BT4 is compatible with Franklin Electric inline pressure boosting controls that automate pressure management. See the inline controls pressure boosting system for automatic variable speed pressure control options compatible with the BT4.

Replacement Parts and Service

The ODP square-flange 2-compartment motor design on the 5 to 25 GPM models allows electrical service without pump disassembly, simplifying motor maintenance and replacement in the field. The back pull-out motor design on the 35 to 45 GPM models allows motor removal without disturbing the pump body or plumbing connections.

Ken’s Distributing Company carries genuine Franklin Electric BT4 Series replacement parts including mechanical seals, impeller stage assemblies, and motor components. When service is needed, call us at 303.699.7845 and we will identify the correct part by model number and get it shipped promptly to minimize system downtime.

Browse our Franklin Electric replacement parts and repair kits for the BT4 Series and all other Franklin Electric pump lines.

Frequently Asked Questions

What does BT4 stand for in Franklin Electric pump naming?

BT4 identifies this as Franklin Electric’s horizontal multi-stage booster pump series, designed for high-pressure water supply and pressure boosting applications from 5 to 45 GPM with discharge pressures up to 400 PSI. It is one of two horizontal multi-stage booster pump series in the Franklin Electric lineup alongside the MH Series.

What is the Tri-Seal floating stage system on the BT4?

The Tri-Seal floating stage system is a patented Franklin Electric design covered under U.S. Patent 7,290,984 that allows each pump stage to float axially on the shaft. This floating arrangement compensates for thermal expansion during pump operation and ensures consistent hydraulic clearances between impellers and diffusers across the operating temperature range. The result is more consistent performance and longer service life compared to fixed-stage designs in continuous booster duty applications.

Is the BT4 certified for drinking water use?

Yes. The BT4 Series is certified to NSF/ANSI/CAN 372 for drinking water contact. This certification confirms that the materials in contact with the pumped water meet the safety requirements for potable water systems. It is a required specification for booster pumps installed in drinking water systems in many states and municipalities.

What is the maximum discharge pressure of the BT4 Series?

The BT4 Series delivers maximum discharge pressures up to 400 PSI depending on model, HP, and number of stages. The 56C pump end models have a shut-off pressure up to 270 PSI. For specific performance data showing pressure at your required flow rate, contact Ken’s Distributing at 303.699.7845.

What is the difference between the BT4 and MH Series booster pumps?

The BT4 delivers higher maximum discharge pressure, a wider flow range up to 45 GPM, the patented Tri-Seal floating stage system, and a 56C pump end option for custom motor installations. The MH Series serves residential and light commercial boosting applications within a more moderate pressure and flow range. The BT4 is the right choice for higher-pressure commercial, RO pre-pressure, and specialized applications. The MH Series fits standard residential and light commercial pressure boosting needs.

Is the BT4 compatible with variable frequency drives?

Yes. The three-phase motor options in the BT4 Series are inverter duty rated, confirming compatibility with variable frequency drive (VFD) controls. This makes the BT4 suitable for variable speed pressure boosting systems that use VFD control for energy-efficient constant pressure operation. Single-phase models are also compatible with Franklin Electric inline pressure boosting controls.

Can I get BT4 replacement parts from Kendisco?

Yes. Ken’s Distributing Company carries genuine Franklin Electric BT4 Series replacement parts including mechanical seals, stage assemblies, and motor components. Call 303.699.7845 for availability and fast shipping on all BT4 service components.

Related Products

• Compare with the MH Series horizontal multi-stage booster pump for residential and light commercial applications
• View compatible Franklin Electric inline pressure boosting controls for automated BT4 pressure management
• See the Franklin Electric end gun booster pump for center pivot irrigation pressure boosting
• Shop Franklin Electric replacement parts and repair kits for all series

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