Franklin Electric BT4 Series Horizontal Multi-Stage Booster Pump & Parts

Franklin Electric BT4 Series Booster Pump models provide multi-stage water-pressure boosting for residential, agricultural and commercial systems. Choose from 5 to 25 GPM models with 1-inch NPT ports, 35 to 45 GPM models with 1.5-inch NPT ports, or motorless NEMA 56C pump ends. Ken’s Distributing Company supplies BT4 pumps and helps identify the correct OEM replacement parts by model and item number.

Need a complete pump or repair parts? Send us the BT4 model or item number, available voltage, required flow and target outlet pressure. We can confirm configuration, fit, price and availability for buyers across the United States and Canada. We reply within one business day.

The MH Series is listed with it under Franklin horizontal booster pumps, so you can compare flow and pressure ranges.

Franklin Electric BT4 Series Booster Pump: Key Specifications

Performance note: The flow numbers identify nominal model families, not guaranteed delivery at a specified pressure. Determine the duty point using the chosen model’s performance curve, available inlet pressure and plumbing losses. The owner’s manual separately states a 500 PSI maximum operating-pressure rating, while Franklin’s product overview gives 400 PSI as its maximum discharge-pressure specification; neither should be used as a promised output pressure.

Choose the BT4 Configuration That Fits Your System

For new installations, first specify required GPM and total dynamic head or target discharge pressure. Next select horsepower, voltage and phase, followed by the motor-enclosure or pump-end arrangement. The same nominal flow is sold in several stage counts and motor ratings, so the item number matters.

BT4 Complete Pumps by Model and Manufacturer Item Number

The manufacturer item numbers below are the ordering references. Each underlined item number links once to its existing dedicated Ken’s Distributing product page. Flow is the nominal catalog series designation, not guaranteed flow at every head.

5–25 GPM Single-Phase BT4 Pumps

5–25 GPM Three-Phase BT4 Pumps

35–45 GPM Single-Phase BT4 Pumps

35–45 GPM Three-Phase BT4 Pumps

BT4 56C Pump Ends Without Motors

Order a 56C pump end when the installation calls for a separately selected NEMA 56C keyed-shaft motor. These are not complete motor-driven booster packages. The list includes manufacturer options for 5-, 20-, 35- and 45-GPM pump ends. Confirm motor speed, enclosure, horsepower, shaft dimensions and coupling fit before ordering.

56C Pump-End Ordering Numbers

Additional 56C Pump-End Options Listed by Franklin Electric

Franklin’s published catalog spells model 4503FTB1S4-PE for item 95924503. Confirm the nameplate/model spelling when requesting this pump end.

How BT4 Multi-Stage Pressure Boosting Works

Inside a BT4, water flows through a series of impeller-and-diffuser stages. Each stage adds head, allowing a relatively compact unit to deliver high pressure while serving the model’s rated flow family. The patented Tri-Seal floating-stage design appears in Franklin’s 5–25 GPM range, with acetal impellers, modified PPO diffusers and 300-series stainless-steel wetted metal components.

For the larger 35- and 45-GPM models, Franklin uses hydraulic stages designed for their higher nominal flows, 1.5-inch connections, a rotatable bracket and NEMA 56C motor mounting. The two ranges should be sized using their own curves rather than treating all BT4 units as interchangeable.

BT4 Applications and Automatic Pressure Controls

• Home and light-commercial boosting: Raise water pressure where municipal or private supply pressure is inadequate, with a properly selected pressure switch, tank or controller.
• Commercial water distribution: Select higher-flow 35- and 45-GPM models when the duty point calls for more water than smaller BT4 hydraulics can provide.
• Filtration and reverse-osmosis feed: Match inlet and discharge conditions to equipment pressure limits and water-treatment specifications.
• Irrigation, spray and misting systems: Use the manufacturer curve to select the necessary flow at operating pressure.
• Equipment replacement: Identify the existing BT4 motor rating, item number and stage count before choosing a complete pump or pump end.

Is the BT4 automatic? A standard BT4 assembly is a pump, not a complete automatic pressure-control system. Automatic start/stop operation needs suitable external controls. See the related Franklin Electric Inline Controls product below, and confirm voltage, current, motor type and application compatibility before ordering controls.

OEM BT4 Replacement Parts: Seals, O-Rings, Bearings and Couplings

Many BT4 repairs do not require a complete new pump. Franklin Electric publishes OEM part numbers for mechanical seals, shaft coupling kits, O-rings, stage assemblies, top bearings and discharge heads. To request repair parts, identify the 5–25 GPM or 35/45 GPM version, complete pump or 56C pump-end style, and original item/model number.

BT4 Stage Assembly Part Numbers by Flow Family

The stage-assembly number can differ by flow family, motor horsepower and stage count. Franklin’s service manual lists these OEM stage assembly references. Confirm the full BT4 model and stage count before ordering.
Match the stage assembly to your motor HP before ordering.

For parts service, ask for the OEM item number and required quantity (for example, a single stage assembly versus a complete set of stages). O-rings, seals, spacers and bearings must match the pump-end design and service revision.

Repair the BT4 Booster Pump or Replace the Complete Unit?

• Replace a seal or O-ring: Consider OEM parts when the motor, stages and pump body remain serviceable and leakage comes from an identified sealing component.
• Repair or replace stage components: Damaged impellers or diffusers can change flow and head. Confirm the original stage count and parts needed for the exact BT4 variant.
• Replace a motor or pump end: For failed motors, compare motor replacement with a 56C pump-end configuration where appropriate. Confirm the shaft and motor mounting before quoting.
• Request a complete BT4 assembly: If multiple hydraulic parts are damaged or a new duty point is required, an appropriately selected new complete pump may be more practical.

BT4 vs. MH Series: Which Booster Pump Fits?

Do not select solely on maximum pressure. Compare GPM at the required head, motor and electrical supply, allowable fluid temperature, pressure control requirements and the available piping layout.

Installation and Model Compatibility Checklist

• Confirm the pump supply and all downstream components are rated for the expected inlet pressure plus pump-generated pressure.
• Use correctly sized suction and discharge plumbing with adequate inlet water and follow the manufacturer’s priming instructions.
• Select the proper electrical supply and check overload protection and motor enclosure for the installation.
• Choose the compatible control method: pressure switch and tank, or a manufacturer-approved inline control arrangement.
• For a 56C pump end, specify the actual motor and keyed shaft rather than assuming the pump end includes a motor.
• For repairs, note whether the unit is 5–25 GPM or 35–45 GPM and provide its complete OEM model/item number.

Request BT4 Pump Prices, Availability or OEM Repair Parts

For complete pumps: Send the required flow (GPM), desired pressure or total dynamic head, incoming pressure, available voltage, single- or three-phase supply, and whether you need a motorized unit or pump end. A photo of the original nameplate is useful for direct replacements.

For OEM replacement parts: Send the pump model, item number and suspected part or part number, plus the condition being repaired. Ken’s Distributing Company can help confirm fit, price and availability. Request a BT4 pump or parts quote, or call 303-699-7845.

Frequently Asked Questions

Is the Franklin Electric BT4 booster pump automatic?

The BT4 itself is a multi-stage pump. An automatic pressure-boosting installation needs compatible external controls such as a pressure switch or suitable inline pump controller. Confirm controller and motor electrical compatibility before ordering.

Which BT4 pump fits a 10-GPM pressure-boosting application?

Several 10-GPM BT4 models have different horsepower and stage counts. Select by required pressure or total dynamic head at the design flow, then match voltage and motor phase. Compare the model/item-number tables above.

What is the difference between a 56C pump end and a complete BT4 pump?

A 56C pump end contains the hydraulic pump assembly for use with a separately supplied NEMA 56C keyed-shaft motor. A complete BT4 assembly includes the motor indicated by its specific ordering row.

Does the BT4 produce 400 PSI at 45 GPM?

Not necessarily. Franklin’s 400 PSI figure is a maximum discharge-pressure specification, not a simultaneous flow-and-pressure operating point. Select the exact motor and stage configuration from its performance curve.

Which BT4 mechanical seal and O-ring parts can I request?

Manufacturer-listed examples include mechanical seals 305421906 and 305421907, 56C pump-end seal 305421003 and O-ring set 305421908. The correct component depends on the pump version and repair scope.

Does NSF/ANSI/CAN 372 mean the entire pump is approved for every drinking-water installation?

No. NSF/ANSI/CAN 372 addresses lead-content requirements for designated water-contact products. Confirm all additional local plumbing, water-quality and system requirements for the specific installation.

Can I buy an individual BT4 impeller or diffuser stage rather than the whole pump?

Yes, Franklin lists replacement diffuser/impeller/disk stage assemblies by nominal flow, plus other service components. Provide the full BT4 model and stage count to confirm the correct OEM part.

Can I run a BT4 with a variable-frequency drive?

Franklin describes the three-phase 5–25 GPM motor models as inverter-duty rated. Select and program the drive to match the actual motor nameplate and manufacturer guidance. Do not assume the same arrangement applies to single-phase motors.

Related Franklin Electric Pumps and Pressure Controls

• Franklin Electric MH Series Horizontal Multi-Stage Booster Pump: compare another multi-stage series for residential, light-commercial and higher-flow service.
• Franklin Electric Inline Controls Pressure Boosting System: explore external automatic start/stop controls, subject to motor and electrical compatibility.
• Franklin Electric End Gun Booster Pump: a different booster application for center-pivot irrigation.
• Franklin Electric Replacement Pump Parts: additional manufacturer series and service components.