Franklin Electric MH Series Horizontal Multi-Stage Booster Pump

The Franklin Electric MH Series Multi-Stage Booster Pump is a horizontal stainless steel, high-efficiency pressure booster designed for residential water pressure boosting, commercial building water supply, irrigation systems, and industrial fluid handling applications. Available in five flow rates from 15 GPM to 90 GPM, with horsepower options up to 7.5 HP in single-phase and three-phase configurations, the MH Series covers a wide range of pressure boosting demands from single-family homes to multi-unit commercial buildings. At Ken’s Distributing Company, we stock the MH Series and can help you select the right flow rate, HP, and phase configuration for your specific system requirements.

What Is the Franklin Electric MH Series Booster Pump?

The MH Series is Franklin Electric’s horizontal multi-stage centrifugal booster pump designed for consistent pressure delivery in water supply and circulation systems. Like all multi-stage centrifugal pumps, the MH Series achieves higher pressures than a single-stage pump of comparable size by stacking multiple impeller and diffuser stages in series along a common shaft, with each stage adding pressure to the water passing through it.

The MH Series splits into two distinct groups based on flow range. The 15 to 45 GPM models target residential and light commercial applications with UL 778 approved motors, NSF/ANSI/CAN 372 drinking water certification, and suction lift capability. The 70 to 90 GPM models serve commercial and industrial applications with a close-coupled design, three-phase IE3 class motor, and enhanced bearing and seal specifications for continuous commercial duty.

Compared to the Franklin Electric BT4 Series, the MH Series serves a somewhat different position in the market. The BT4 reaches higher maximum discharge pressures of up to 400 PSI and covers a flow range of 5 to 45 GPM with the patented Tri-Seal floating stage system. The MH Series extends the upper flow range to 90 GPM with the 70 and 90 GPM models and includes the higher temperature capability of 225 degrees F on the 15 to 45 GPM group, making it appropriate for hot water circulation and process water applications where the BT4’s 120 degrees F limit would be a constraint.

Kendisco is an authorized Franklin Electric distributor. Every MH Series pump ordered through Ken’s Distributing Company is a genuine Franklin Electric product with full manufacturer support and genuine replacement parts availability.

MH Series Model Groups: 15 to 45 GPM vs. 70 to 90 GPM

Feature	15 to 45 GPM MH Series	70 to 90 GPM MH Series
Flow Range	15, 30, and 45 GPM	70 and 90 GPM
Max Pressure	Up to 140 PSI	Commercial pressure range
Max Fluid Temperature	225 degrees F	Clear, non-loaded fluids standard temp
Motor Type	UL 778 indoor/outdoor square flange	IE3 class three-phase TEFC, IP55
Motor Phase Options	Single-phase or three-phase	Three-phase only
HP Range	Up to 7.5 HP	Commercial HP range
Impeller/Diffuser Material	300 Series Stainless Steel	300 Series Stainless Steel
Mechanical Seal	FKM elastomers	Carbon/Silicon Carbide/EPDM
Suction Lift	Up to 10 feet	Not specified for suction lift
NSF Certification	NSF/ANSI/CAN 372	Standard
Design	Horizontal multi-stage	Compact close-coupled
Best For	Residential, light commercial, hot water, potable	Commercial buildings, industrial, high flow

Technical Specifications

15 to 45 GPM Models

Specification	Value
Available Flow Rates	15, 30, and 45 GPM
Max Discharge Pressure	Up to 140 PSI
Max Fluid Temperature	225 degrees F
Suction Lift Capability	Up to 10 feet
Wetted Components	All 300 Series Stainless Steel
Mechanical Seal	FKM elastomers
Motor Certification	UL 778 approved indoor/outdoor
Motor Frame	Square flange
HP Options	5 motor HP size options, up to 7.5 HP
Phase Options	Single-phase and three-phase
NSF Certification	NSF/ANSI/CAN 372

70 to 90 GPM Models

Specification	Value
Available Flow Rates	70 and 90 GPM
Impeller and Diffuser	300 Series Stainless Steel
Mechanical Seal	Carbon/Silicon Carbide/EPDM
Motor Type	Three-phase, 2-pole, IE3 class, asynchronous
Motor Enclosure	TEFC, IP55 protection rating
Motor Insulation	Class F
Bearing Design	Oversized shaft, ball bearing in motor bracket and motor
Neck Ring	Floating PPS for wear resistance
Fluid Type	Clear, non-loaded fluids
Design	Compact close-coupled

Order Information

Multi-Stage Single Phase Model

Multi-Stage Three Phase Model

Understanding the MH Series Model Code

The MH Series model designations follow a consistent naming convention that tells you the key specifications at a glance. Using the model 15FMH05S2 as an example:

Code Element	Meaning
15	Flow rate: 15 GPM
FMH	Franklin Electric Multi-stage Horizontal pump
05	Motor HP: 0.5 HP (1/2 HP)
S	Single-phase motor
2	Number of stages
-T suffix	Three-phase motor version

This naming convention makes it straightforward to confirm you are ordering the right model by verifying the flow rate, HP, phase, and stage count directly from the model number before placing your order.

Key Features: 15 to 45 GPM MH Series

• All 300 Series Stainless Steel Wetted Components: Every component in contact with the pumped liquid is 300 Series stainless steel. This provides excellent corrosion resistance for drinking water, chemically treated water, hot water circulation, and process water applications where cast iron or aluminum components would corrode and contaminate the fluid over time.
• 225 Degree F Maximum Fluid Temperature: The 15 to 45 GPM MH models handle fluid temperatures up to 225 degrees F. This is a meaningful specification that makes the MH Series appropriate for hot water recirculation systems, domestic hot water booster applications, and process water systems at elevated temperatures where the BT4 Series 120 degree F limit would be a constraint.
• FKM Mechanical Seal: FKM (Fluoroelastomer) elastomers in the mechanical seal provide broad chemical compatibility and temperature resistance beyond what standard BUNA or Nitrile elastomers offer. This extends the seal service life in chemically treated water supply systems and hot water circulation applications.
• UL 778 Approved Indoor/Outdoor Motors: The UL 778 standard covers motors used in pump applications. Both indoor and outdoor installation are covered by the same motor, eliminating the need to specify different motor enclosures for different installation environments on the 15 to 45 GPM models.
• Suction Lift Capability up to 10 Feet: The 15 to 45 GPM MH models can operate with the water source up to 10 feet below the pump inlet. This allows the MH Series to be used in applications where the supply tank or reservoir is below the pump installation point, including basement tank setups and ground-level cistern installations.
• NSF/ANSI/CAN 372 Drinking Water Certification: Certified safe for contact with potable water. Required for booster pump installations in drinking water systems in many jurisdictions and a standard specification requirement for residential and commercial water supply applications.
• Five HP Size Options up to 7.5 HP: The range of available HP options within each flow rate allows the system designer to match the pump performance curve precisely to the required pressure boost at the system flow rate, rather than accepting the closest available single option.
• Single-Phase and Three-Phase Options: Both single-phase and three-phase motor options are available for the 15 to 45 GPM group, covering residential installations with single-phase power and commercial installations with three-phase service. Single-phase models are dual voltage at 115 or 230 VAC. Three-phase models accept 230 or 460 VAC.

Key Features: 70 to 90 GPM MH Series

• Compact Close-Coupled Design: The 70 to 90 GPM models use a compact close-coupled configuration where the pump mounts directly to the motor without a separate bearing frame. This keeps the overall footprint smaller than an equivalent frame mount configuration, which matters in commercial mechanical rooms where space is limited.
• IE3 Class Motor Efficiency: The three-phase motor meets IE3 (Premium Efficiency) classification, the highest standard motor efficiency class under the IEC international motor efficiency rating system. IE3 motors consume less energy than IE1 or IE2 motors at equivalent output, providing meaningful operating cost savings in commercial applications running significant duty cycles.
• IP55 Motor Protection: IP55 is the International Protection rating indicating protection against dust ingress and protection against water jets from any direction. This rating makes the 70 to 90 GPM models suitable for outdoor and wet mechanical room installations without additional motor enclosure protection.
• Class F Motor Insulation: Class F insulation is rated for continuous operation at winding temperatures up to 155 degrees C, providing a significant thermal safety margin above the ambient plus rise temperatures experienced in commercial continuous-duty applications.
• Carbon/Silicon Carbide/EPDM Mechanical Seal: The silicon carbide seal faces on the 70 to 90 GPM models provide better abrasion resistance than carbon and ceramic faces in applications where the fluid carries fine particles. EPDM elastomers extend the chemical compatibility range for specific fluid types.
• Floating PPS Neck Ring: The floating neck ring in PPS (Polyphenylene Sulfide) provides better wear resistance than standard materials at the critical wear interface between the impeller and the stage casing. PPS maintains its mechanical properties at elevated temperatures and in chemically aggressive environments better than many thermoplastic alternatives.
• Heavy-Duty Oversized Motor Shaft: The oversized shaft on the 70 to 90 GPM models handles the higher torque loads generated by the larger motor and pump combination with appropriate safety margins, extending bearing and shaft seal life at commercial duty cycle intensities.
• Flexible Application Baseplate: The adjustable baseplate accommodates different mounting configurations in commercial mechanical rooms, allowing the pump to be installed in the orientation and position that best suits the existing plumbing layout without requiring custom fabricated mounts.

Applications and Industries

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

• Residential Water Pressure Boosting: Homes with insufficient incoming pressure from municipal supply or private water systems use the MH Series 15 GPM models to boost pressure to comfortable residential levels for showers, fixtures, and appliances. NSF/ANSI/CAN 372 certification confirms safety for drinking water contact.
• Apartment Buildings and Multi-Unit Residential: Multi-story apartment buildings where upper floor units experience low pressure due to elevation use the MH Series 30 to 45 GPM models to maintain consistent pressure across all units. The five HP size options allow precise matching of the booster to the building’s demand and pressure requirements.
• Commercial Building Water Supply: The 45 to 90 GPM models handle the higher demand of commercial building water supply, including office buildings, hotels, and retail facilities requiring consistent pressure at multiple fixture points simultaneously.
• Hot Water Circulation Systems: The 225 degree F maximum fluid temperature of the 15 to 45 GPM models makes them appropriate for domestic hot water recirculation systems that maintain hot water availability at all fixture points by continuously circulating water through the hot water distribution loop.
• Irrigation Pressure Boosting: Drip irrigation, micro-sprinkler, and sprinkler systems requiring consistent operating pressure use the MH Series to boost supply pressure to the system operating requirement. The 15 to 45 GPM models cover the demand range of most residential and light commercial irrigation systems.
• Industrial Fluid Handling: Industrial process water circulation, cooling water supply, and fluid transfer applications where consistent pressure is needed use the MH Series for its stainless steel construction and chemical compatibility through FKM or EPDM elastomer seal options.
• Booster Sets: Municipal and commercial pressure booster stations use multiple MH Series pumps in parallel or series configurations to achieve the required system pressure and flow capacity with built-in redundancy through multiple pump units.
• Water Circulation Systems: HVAC chilled and hot water circulation, process cooling loops, and building water treatment systems use the MH Series for reliable, efficient circulation at the required pressure differentials.

MH Series vs. BT4 Series: Choosing the Right Franklin Electric Multi-Stage Booster

Both the MH and BT4 are Franklin Electric horizontal multi-stage booster pumps available at Kendisco. Here is a direct comparison to help you choose the right one.

Feature	MH Series	BT4 Series
Flow Range	15 to 90 GPM	5 to 45 GPM
Max Discharge Pressure	Up to 140 PSI (15 to 45 GPM models)	Up to 400 PSI
Max Fluid Temperature	225 degrees F (15 to 45 GPM models)	120 degrees F
Stage System	Standard multi-stage	Tri-Seal floating stage (patented)
NSF Certification	NSF/ANSI/CAN 372	NSF/ANSI/CAN 372
56C Pump End Option	No	Yes
Suction Lift	Up to 10 feet	Not rated for suction lift
High Flow Option	Yes, 70 and 90 GPM models	No, max 45 GPM
Hot Water Capability	Yes, up to 225 degrees F	Limited to 120 degrees F
Best For	High flow, hot water, suction lift, residential	High pressure, RO, specialized applications

Choose the MH Series when you need flow rates above 45 GPM, hot water circulation capability above 120 degrees F, suction lift installation, or a standard multi-stage configuration for residential and light commercial pressure boosting. Choose the BT4 Series when you need the highest possible discharge pressure up to 400 PSI, the patented Tri-Seal floating stage system, or the 56C pump end option for custom motor installations. Call Ken’s Distributing at 303.699.7845 to discuss your specific pressure, flow, temperature, and installation requirements and we will point you to the right series.

Installation and Compatibility

• Voltage Selection: Single-phase 15 to 45 GPM models accept 115 VAC or 230 VAC. Set the motor for the correct voltage before startup. Three-phase models accept 230 or 460 VAC. Confirm your supply voltage before ordering to ensure the model you select matches your electrical service.
• Suction Lift Applications: The 15 to 45 GPM MH models support suction lift installations up to 10 feet. Ensure the suction line is properly sealed and that a foot valve is installed at the water source to retain liquid in the suction line between pump cycles for reliable startup.
• Pressure Relief: Install a pressure relief valve on the discharge side set below the system maximum working pressure to protect the piping and fixtures from overpressure conditions.
• Check Valve: Install a check valve on the discharge side to prevent backflow through the pump when the booster is not running. This is particularly important in systems with elevated discharge pressure that could drive backflow through a stopped pump.
• Pressure Tank: Including a small pressure tank downstream of the MH Series pump reduces pump cycling frequency on systems with intermittent demand and protects against water hammer in the distribution system.
• Hot Water Applications: For hot water circulation with the 15 to 45 GPM models, confirm that all system components including piping, valves, and fittings are rated for the fluid temperature in your application up to the 225 degree F maximum.
• Mechanical Seal: Never run the MH Series dry. The mechanical seal requires liquid contact for lubrication and cooling throughout all operation. Install a low-pressure or flow cutoff switch on the suction side to prevent the pump from running when the supply is interrupted.
• Inline Controls: The MH Series is compatible with Franklin Electric inline pressure boosting controls for automated variable speed pressure management. Combining the MH Series with inline controls provides constant pressure delivery that adjusts to varying demand without pressure fluctuations.
• Baseplate and Mounting: For 70 to 90 GPM models, use the flexible application baseplate to position the pump in the optimal orientation for the available mechanical room plumbing layout before securing to the floor or frame.

Replacement Parts and Service

The stainless steel construction of the MH Series means the primary service components are the mechanical seal and the impeller stage assemblies rather than corrosion-related pump body components. The square flange motor design on the 15 to 45 GPM models allows motor service and replacement without disturbing the pump hydraulic assembly.

Ken’s Distributing Company carries genuine Franklin Electric MH Series replacement parts including FKM mechanical seals, silicon carbide seals for the 70 to 90 GPM models, 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.

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

Frequently Asked Questions

What does MH stand for in Franklin Electric pump naming?

MH identifies this as Franklin Electric’s horizontal multi-stage booster pump series. The designation FMH in the model code stands for Franklin Electric Multi-stage Horizontal, confirming the pump type and orientation. It is one of two horizontal multi-stage booster pump series in the Franklin Electric lineup alongside the higher-pressure BT4 Series.

What is the maximum discharge pressure of the MH Series?

The 15 to 45 GPM MH Series models deliver discharge pressures up to 140 PSI depending on model, HP, and number of stages. For specific performance data showing pressure at your required flow rate, contact Ken’s Distributing at 303.699.7845 with your flow and head requirements.

Can the MH Series handle hot water?

Yes. The 15 to 45 GPM MH Series models are rated for fluid temperatures up to 225 degrees F, making them suitable for domestic hot water circulation, hot water booster, and process water applications at elevated temperatures. The 70 to 90 GPM models are designed for clear, non-loaded fluids at standard temperatures. Confirm the temperature rating of the specific model you are considering before ordering for hot water applications.

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

The MH Series extends to higher flow rates with 70 and 90 GPM models, handles higher fluid temperatures up to 225 degrees F on the 15 to 45 GPM group, and supports suction lift installations up to 10 feet. The BT4 Series reaches higher maximum discharge pressures up to 400 PSI, offers the patented Tri-Seal floating stage system, and includes a 56C pump end option for custom motor installations. The BT4 is the right choice for high-pressure and specialized applications. The MH Series is the right choice for high flow, hot water, and suction lift applications.

Is the MH Series certified for drinking water use?

Yes. The MH Series 15 to 45 GPM models are certified to NSF/ANSI/CAN 372 for drinking water contact. This certification confirms the materials in contact with the pumped water meet potable water safety requirements. It is a required specification for booster pumps in drinking water systems in many jurisdictions.

What voltage does the MH Series require?

Single-phase MH Series models accept 115 VAC or 230 VAC and are dual voltage. Three-phase models accept 230 VAC or 460 VAC. Confirm your available electrical supply voltage before ordering to ensure you select the correct model configuration.

Can I get MH Series replacement parts from Kendisco?

Yes. Ken’s Distributing Company carries genuine Franklin Electric MH Series replacement parts including FKM mechanical seals, silicon carbide seals for 70 to 90 GPM models, impeller assemblies, and motor components. Call 303.699.7845 for availability and fast shipping on all MH Series service components.

Related Products

• Compare with the BT4 Series horizontal multi-stage booster pump for high-pressure applications up to 400 PSI
• View compatible Franklin Electric inline pressure boosting controls for automated MH Series 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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