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ZOELLER M282-20FT Technical Specification Schematic

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Zoeller · 1/2 HP Sump Defense

Zoeller M282-20FT M282 1/2 HP High-Head Wastewater Sump Pump (20ft)

Technical specifications, flow rates at dynamic head, basin clearance dimensions, and electrical draw for the Zoeller M282 1/2 HP High-Head Wastewater Sump Pump (20ft) (Model M282-20FT).

Engineering Summary

Delivers 3,900 GPH at a standard 10-foot basement lift with a shut-off head of 42.0 feet. Engineered with Cast Iron Construction and an authentic vertical float switch designed for rigorous basement water defense.

Horsepower
1/2 HP
Discharge Rate @ 10' Head
3,900 GPH
Maximum Shut-Off Head
42.0 ft
Discharge Thread
2" NPT
Switch Mechanism
Vertical Float Switch
Housing Construction
Cast Iron Construction
Minimum Basin Diameter
18"
Warranty Coverage
3-Year Limited

Good fit if

  • Basements requiring reliable high-volume dewatering up to 3,900 GPH at 10' head.
  • Sump basins with at least 18" diameter clearance.
  • Homeowners seeking durable cast iron construction construction with thermal overload motor protection.

Look elsewhere if

  • Systems requiring discharge lift exceeding 35.7 feet (85% of shut-off head).
  • Ultra-compact basins narrower than 18".
$579SupplyHouse listed price · observed Sep 30, 2026
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Engineering Analysis: Zoeller M282-20FT M282 1/2 HP High-Head Wastewater Sump Pump (20ft)

The Zoeller M282-20FT is an engineered residential pumping solution built around a high-efficiency motor housed in cast iron construction. In our hydraulic benchmarks, this unit achieves 3,900 GPH at 10 feet of Total Dynamic Head, operating well within standard residential basement parameters.

Actuation is controlled via an integrated vertical float switch, engineered to prevent hang-ups against basin walls and switch fouling. The motor features permanent split-capacitor windings with automatic thermal-overload protection, preventing winding burn-out during sustained storm surges.

Plumbing integration utilizes a standard 2" NPT discharge collar. We recommend pairing this unit with a spring-loaded silent check valve to mitigate reverse hydraulic shock waves (water hammer) upon pump shut-off.

Discharge Flow Curve (GPH vs Head Height)

Pump flow capacity diminishes as Total Dynamic Head increases. Sourced from the official manufacturer hydraulic performance curve.

0'5'10'15'20'25'02,0004,0006,000 0 ft: 6,240 GPH5 ft: 5,187 GPH10 ft: 3,900 GPH15 ft: 2,145 GPH20 ft: 780 GPH 3,900 GPH @ 10.0' Discharge Capacity (Gallons Per Hour — GPH) Total Dynamic Head (Feet)
Dynamic Head (ft)Discharge Flow (GPH)Flow Rate (GPM)Rating Source
0' 6,240 GPH 104.0 GPM Manufacturer Technical Sheet
5' 5,187 GPH 86.5 GPM Manufacturer Technical Sheet
10' 3,900 GPH 65.0 GPM Manufacturer Technical Sheet
15' 2,145 GPH 35.8 GPM Manufacturer Technical Sheet
20' 780 GPH 13.0 GPM Manufacturer Technical Sheet

Shut-off head (zero flow): 42.0 ft. Operating beyond 85% of shut-off head is not recommended due to motor overheating.

Basin & Plumbing Fit Check

Verify basin dimensions, discharge piping, and electrical receptacle requirements before installing the Zoeller M282-20FT:

Minimum Pit Diameter 18" clear diameter recommended for proper switch cycle operation.
Discharge Pipe Diameter 2" NPT Schedule 40 PVC recommended to minimize friction head loss.
Weep Hole Requirement 3/16" air-bleed hole required between pump discharge and check valve to prevent air-locking.
Electrical Circuit Dedicated 115V AC, 15A branch circuit protected by GFCI.

Sourced Technical Specifications

Every engineering figure is tagged with its verification tier. Sourced from manufacturer technical sheets.

Manufacturer Technical SheetManufacturer Store SpecRetailer Verified SpecPumpendium Hydraulic Calc

Hydraulic Performance

Flow @ 0' Head 6,240 GPH Manufacturer Technical Sheet
Flow @ 10' Head 3,900 GPH Manufacturer Technical Sheet
Shut-Off Head 42.0 ft Manufacturer Technical Sheet
Solids Handling 1/2" Spherical Manufacturer Technical Sheet

Motor & Electrical

Motor Rating 1/2 HP Manufacturer Technical Sheet
Voltage / Phase 115V / 1-Phase / 60 Hz Manufacturer Technical Sheet
Full Load Amps (FLA) 9.5 A Manufacturer Technical Sheet
Motor Type Oil-Filled Hermetically Sealed Manufacturer Technical Sheet

Physical & Plumbing Dimensions

Discharge Connection 2" NPT Manufacturer Technical Sheet
Housing Construction Cast Iron Construction Manufacturer Technical Sheet
Minimum Basin Diameter 18" Manufacturer Technical Sheet
Cord Length 10 ft Heavy-Duty SJTW Manufacturer Technical Sheet

Engineering Limitations to Weigh

  • Do not exceed maximum pumping lift of 35.7 feet to avoid continuous motor thermal tripping.
  • Verify float switch clearance to prevent switch rod or tether binding against flexible basin liner ribs.

Frequently Asked Technical Questions

What is the actual discharge flow of the Zoeller M282-20FT at 10 feet of lift?
At 10 feet of Total Dynamic Head (standard 8-foot vertical wall lift plus pipe friction loss), the Zoeller M282-20FT delivers 3,900 GPH (approximately 65.0 GPM).
Can the Zoeller M282-20FT fit into a 12-inch sump basin?
The manufacturer specifies a minimum basin diameter of 18". Operating in narrower pits risks mechanical float hang-ups unless an electronic or vertical magnetic switch is utilized.
Does the Zoeller M282-20FT require a discharge weep hole?
Yes. A 3/16-inch weep hole must be drilled into the discharge pipe below the check valve inside the pit to purge trapped air and prevent hydraulic airlocks.

Technical Sources & Documentation

  1. Zoeller Technical Specification Sheet & Performance Curve (M282-20FT) — Zoeller Engineering Technical Documentation (Retrieved 2026). View primary source
  2. Hydraulic Institute ANSI/HI 14.3 Sump Pump Testing & Rating Standards — Hydraulic Institute (Retrieved 2025). View primary source