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WATER ENTRY IN BUILDINGS

AGE of MOLD - Old is the Mold?

BASEMENT CEILING VAPOR BARRIER
BASEMENT MOLD WATER IMPACT
BASEMENT WATERPROOFING
BRICK WALL DRAINAGE WEEP HOLES
BUCKLED FOUNDATIONS due to INSULATION?
BUILDING DAMAGE ASSESSMENT & REPAIR

CONDENSATION on WINDOWS & SKYLIGHTS
CRAWL SPACES

DEW POINT TABLE - CONDENSATION POINT GUIDE

EFFLORESCENCE, Salts & White / Brown Deposits

FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOD DAMAGED FOUNDATIONS
FLOOD VENTS & FLOOD PORTS
FLOODS IN BUILDINGS-mold
FLOOR DAMAGE DIAGNOSIS
FOOTING & FOUNDATION DRAINS
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CRACKS & DAMAGE GUIDE
FOUNDATION WATERPROOFING
FRENCH DRAINS
FREEZE-PROOF A BUILDING
FROST HEAVES, FOUNDATION, SLAB

HUMIDITY LEVEL TARGET

ICE DAM PREVENTION

MOISTURE CONTROL in BUILDINGS
MOLD INFORMATION CENTER
NOISE / SOUND DIAGNOSIS & CURE

ODORS & SMELLS DIAGNOSIS & CURE

SEWAGE BACKUP, WHAT TO DO
SEWAGE BACKUP TEST & CLEANUP
SEWAGE BACKUP PREVENTION
SEWAGE PUMPS
SEWAGE PUMP CLOG DAMAGE
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
SUMP PUMPS
SWEATING (CONDENSATION) on PIPES, TANKS

TERMITES
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES

VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS

WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING

More Information

Duplex sump pump installation Guide to Single vs Duplex Sump Pump Installations
     

  • When should we install more than one sump pump; how to wire duplex sump pump installations.
    • Two Types of Duplex Sump Pump Installations: Alternating and Reserve
    • Where and how to install sump pumps
    • How to inspect & maintain sump pumps to remove water from buildings or to prevent basement leakage or crawl space water entry
  • SEPTIC SYSTEM PUMPS - separate article
  • SEWAGE EJECTOR / GRINDER PUMPS - separate article
  • SEWAGE PUMP CLOG DAMAGE - separate article
  • SUMP PUMPS - topic home page
    • Sump Pump Discharge - separate article - Where and how to install sump pumps; Where does the sump pump send its Discharge Water?
    • Sump Pump Inspection - separate article - Guide to Inspecting & Troubleshooting De-Watering Sump Pumps
    • Sump Pump Types - separate article - How to determine the sump pump capacity you need - sump pump sizing table & calculations
    • Submersible Sump Pump Guide - separate article
    • Pedestal Type Sump Pump Guide - separate article
    • Battery Backup Sump Pump Choices - separate article
    • Water Powered Sump Pump Guide - separate article
  • Sump Pump Single vs Duplex
  • Septic Pump Duplex System Designs - separate article
  • Questions & Answers about duplex sump pumps and backup sump pump systems to handle large basement or crawl space flooding or water entry
  • References

Click to Show or Hide Related Topics

  • WATER ENTRY in buildings - home
  • ATTIC LEAKS Moisture or Mold
  • BARRIERS, EXTERIOR WATER
  • BASEMENT CEILING VAPOR BARRIER
  • BASEMENT De-Watering Systems
  • BASEMENT HEAT LOSS
  • BASEMENT LEAKS, INSPECT FOR
  • BASEMENT WATERPROOFING
  • BASEMENT WATER ENTRY PREVENTION
  • CATCH BASINS
  • CHIMNEY LEAKS
  • CONDENSATION on WINDOWS, SKYLIGHTS
  • CORROSION in ELECTRICAL PANELS
  • CRAWL SPACE DRYOUT PROCEDURES
  • DEW POINT CALCULATION for WALLS
  • DEW POINT TABLE
  • DRYER VENTING
  • DRYWELLS, FRENCH DRAINS for FLAT SITES
  • DRYWELL DESIGN & USES
  • EFFLORESCENCE, Salts & White / Brown Deposits
  • ELECTRIC PANEL MOISTURE
  • EXTERIOR WATER SOURCE ELIMINATION
  • FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
  • FLOOD DAMAGED FOUNDATIONS
  • FLOOD VENTS & FLOOD PORTS
  • FLOODS IN buildings-priorities
  • FOUNDATION DRAINS, INTERIOR
  • FOUNDATION WATERPROOFING
  • GEOTEXTILES & DRAINAGE MATS
  • GRADING, DRAINAGE & SITE WORK
  • GUTTERS & DOWNSPOUTS - home
  • HUMIDITY CONTROL & TARGETS INDOORS
  • HOUSEWRAP AIR & VAPOR BARRIERS
  • LOG HOME Leak Diagnosis & Cure
  • LOG HOME Condensation
  • MOISTURE in BUILDING WALLS, EFFECTS
  • MOISTURE in CELLULOSE INSULATION
  • MOISTURE CALCULATIONS
  • MOISTURE CONTROL in BUILDINGS - home
  • MOISTURE METER STUDY
  • MOISTURE PROBLEMS: CAUSE & CURE
  • MOLD in buildings
  • MOLD PREVENTION AFTER FLOODING
  • MOLD RESISTANT CONSTRUCTION
  • PERIMETER DRAIN SYSTEMS
  • ROOF VENTILATION SPECIFICATIONS
  • SOFFIT INTAKE VENTS & Attic Condensation
  • SEALERS, Basement Floor & Wall Moisture
  • SEWAGE BACKUP, WHAT TO DO
  • SITE & SURFACE DRAINAGE
  • SUMP PUMPS
  • SWEATING PIPES, TANKS
  • VENTILATION in BUILDINGS - home
  • WALL / WINDOW LEAK DIAGNOSIS
  • WET BASEMENT PREVENTION
  • WINDOW / DOOR AIR LEAK SEALING HOW TO
  • WINDOW FLASHING & SEALING
  • WINDOW LEAKS INTO BASEMENT
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

This article explains when, where, and how multiple or duplex sump pumps are used in buildings, describes the types of sump pumps, and describes how sump pumps should be installed, inspected, and maintained.

Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.

Two Types of Sump Pump Installations - Simplex and Duplex Pumps

Photo of a common sump pump used in a modern basement

A sump pump is normally installed in a pit at the low end of a basement or crawl space floor or in another location where water needs to be removed such as in a boiler pit or an outdoor well pit. Also see SUMP PUMPS GUIDE and SEPTIC SYSTEM PUMPS.

On occasion we find that we need to install two or more sump pumps inside or outside of a building foundation to remove water from around the foundation of a poorly-sited (too low) building which has no natural drainage path to dispose of ground water by gravity.

Single submersible or pedestal sump pump: The photo on the left is what you're likely to see if your basement has a modern sump pump.

A pedestal type pump must keep its motor out of water and dry.

Regardless of which type of pump we select, pedestal or submersible sump pump, many installations require that only one single pump be installed.

We discuss the details of submersible and pedestal sump pump types at Four Common Types of Sump Pumps.


Duplex sump pump installation

Duplex sump pumps: The photo at left shows a duplexed sump pump system using pedestal type sump pumps. This was a really wet basement - a single sump pump simply could not keep up. In this installation .

When a building footprint or foundation layout is complex, or where the building is constructed over both basement space and one or more crawl spaces, it may be necessary to install multiple sump pumps to protect these various areas.

In a single large basement whose floor did not slope uniformly to a single low corner, it may be more economical to install two or even more sump pumps in problem areas than to tear up the entire basement floor to install a sub-slab drainage system.

Two Types of Duplex Sump Pump Installations: Alternating and Reserve

Reserve septic backup design: the backup pump never runs unless the primary pump has failed or is overloaded. A simple installation provides a pump control float switch that turns on the backup pump only water in the pumping chamber reaches a level above that normally handled by the primary sump pump.

This approach provides both pump backup and the ability to handle surges in building water entry loads on the sump pump system.

Alternating septic pump design: the two sump pumps are installed at the same location but are wired so that the pumps take turns, first one, and next cycle the other pump is turned on by the float switch.

This dual pump hookup is more common among septic pumping stations than among home sump pump de-watering systems, but it may be appropriate where a large volume of ground water has to be kept constantly out of a building.

An example we've seen was in the basement of a home on Long Island, NY in which the level of the basement slab was so low that flooding from Long Island sound would be nearly constant if the pumps failed.

The alternating sump pump approach has the advantage that both pumps are being exercised regularly, which reduces the chance of the ugly discovery that in the event you have to rely on a backup sump pump which has been sitting idle, waiting its chance to run, has in the interim, died.


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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

  • [1] pending
  • [2] Wayne sump pumps such as the Wayne CDU800 1/2HP product specifications
  • [3] Zoeller sump pumps, such as the Zoeller M53 1/2HP sump pump, the Zoeller 98-0001 1/2HP , the Zoeller 57-0001 M57 high capacity pump, and Zoeller "Old Faithful 81 pedestal pup, Zoeller® Company, Website: http://www.zoellerpumps.com/ , Email: zcotechnical@zoeller.com. 
  • [4] "Installation Instructions, Pedestal Pumps Dewatering and Sump, 81, 82, 84 Series", Zoeller Pump Co.®, PO Box 16347, Louisville KY 40256-0347, Tel: 800-928-PUMP Website: www.zoeller.com
  • "International Private Sewage Disposal Code," 1995, BOCA-708-799-2300, ICBO-310-699-0541, SBCCI 205-591-1853, available from those code associations.
  • "Manual of Policy, Procedures, and Guidelines for Onsite Sewage Systems," Ontario Reg. 374/81, Part VII of the Environmental Protection Act (Canada), ISBN 0-7743-7303-2, Ministry of the Environment,135 St. Clair Ave. West, Toronto Ontario M4V 1P5 Canada $24. CDN.
  • ...

 

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • Home Reference Book - Carson DunlopThe Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
  • GO TO Carson Dunlop's Home Study Course Information - How to Become a Home Inspector: Carson Dunlop's nationally recognized Home Study Course, selected by ASHI the American Society of Home Inspectors and other professionals and associations. This website author is a contributor to this course.
    Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd
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