Norweco Singulair Aerator Replacement (Green 96 and Bio-Kinetic)

Why this matters

The Norweco Singulair Green aspirating aerator is the heart of every Singulair Model 96 and Bio-Kinetic ATU. When the aerator stalls or the motor seizes, dissolved oxygen in the aeration chamber crashes within hours, the bacterial floc dies back, effluent BOD spikes, and on a NSF/ANSI 40 system the homeowner is in violation of their operating permit within a single 24-hour service-provider window. Most jurisdictions in the Singulair install base (Ohio, Indiana, Kentucky, Tennessee, North Carolina, Florida) require a Norweco-certified service provider to do the swap and log it. The mechanical job is simple; the certification, model identification, and warranty paperwork is what trips crews up.

Identify the exact aerator model

The Singulair aerator changed castings three times since 2005. Pulling the wrong replacement loses you a day. Read the data tag inside the access lid:

• Singulair Green Model 96 (current) - aerator P/N MSCB-001-AA (115 V, 4.0 amp draw, 1725 RPM). Black motor housing, integrated cord grip.
• Singulair Bio-Kinetic Model 960 (current commercial) - aerator P/N MSCB-002-AA (same motor, longer shaft).
• Singulair Green pre-2018 - P/N MS-960CB-AA, superseded by MSCB-001-AA. Mounting flange is compatible.
• Singulair Classic pre-2005 - older 1/2 HP motor, P/N MS-961-AA, NOT backward-replaceable with the current aerator without the conversion kit (P/N CK-960).

If the unit is more than 15 years old, photograph the data tag and call Norweco tech support (800-NORWECO) with the serial - the conversion kit may be the right answer instead of an aerator swap.

Tools and parts to stage

• Replacement aerator (Norweco-OEM only - aftermarket aerators void NSF/ANSI 40 listing and most state operating permits)
• New gasket kit (P/N MSGK-1) - never reuse the old gasket
• Stainless lift hook (1/2 inch all-thread, two nuts, two washers) for pulling the aerator straight up out of the well
• Multimeter
• Insulated screwdrivers
• Cable lockout for the disconnect at the control panel
• Norweco service log sheet (or the state-required equivalent in FL / IN / TN)

Lockout and verify de-energization

The control panel is typically a NEMA 3R box on a post within 25 feet of the lid. Open the panel, throw the disconnect to OFF, and apply a personal lockout. Verify zero voltage at the aerator terminals inside the panel - not just at the breaker. Singulair Green panels run the aerator on a continuous duty cycle by default; the alarm float and audible buzzer run on a separate 24 VAC sub-circuit that does NOT de-energize when you kill the aerator breaker. Tape the audible alarm or pull its plug before working - it will sound the moment you disconnect the aerator and the customer will be in the yard within 30 seconds.

Pull the old aerator

1. Remove the riser lid bolts (typically 6 stainless flange bolts, 1/2 inch socket).
2. Lift the cast iron lid straight off; the aerator hangs from the lid by its motor bracket.
3. Disconnect the aerator cord at the wire nuts above the lid - cut and cap if the splice is corroded; do not pull the cord through the gland.
4. With a helper, tip the lid 30 degrees and walk the aerator shaft straight up out of the aeration chamber. The shaft is 30-36 inches long depending on model and any side load will bend it.
5. Set the old aerator on a tarp - the motor housing is full of grease and the aspirator tip is coated in floc.

Inspect what the dead aerator tells you

A Singulair aerator that died young (under 5 years) failed for a reason. Read it before you install the new one:

• Black grit packed into the aspirator tip: the upstream trash trap or pre-treatment compartment is not catching solids - schedule a tank pump.
• Heavy white scale on the shaft: high-hardness raw water; consider a softener upstream of the home discharge.
• Burnt motor windings (acrid smell, melted varnish): the panel's overload protection failed - test panel before installing new motor.
• Sheared coupling between motor shaft and aspirator: the unit has been running unbalanced for months; check that the chamber baffle has not rotated.

If the aspirator tip is intact and the motor windings test open, you have a simple motor failure - swap and move on.

Install the new aerator

1. Place a fresh MSGK-1 gasket on the lid flange. Do not use silicone, RTV, or pipe dope - the gasket is a closed-cell EPDM and will swell against any sealant.
2. With the lid tilted 30 degrees, lower the new aerator shaft into the chamber. The aspirator tip should rest 18-22 inches below the static water line per the Norweco install sheet for your tank size.
3. Seat the lid flush. Hand-thread all 6 bolts before torquing any. Torque in a star pattern to 18 ft-lb. Over-torquing crushes the gasket and creates an air leak that mimics a stalled aerator.
4. Land the cord into the gland fitting with the strain-relief loop above the splice, not below. Wire nut splices need to be in a NEMA 3R J-box on the post, not buried in the soil.
5. Confirm the cord at the panel terminates on the AERATOR terminals (typically Red-Black), not the BLOWER terminals on a hybrid unit.

Energize and verify

Remove the lockout. Energize. The aerator should ramp to full speed within 2 seconds, draw within nameplate (4.0 amps for the MSCB-001-AA), and within 60 seconds you should see a vigorous boil in the aeration chamber visible through the chamber inspection port. Run for 15 minutes. Recheck amp draw - should hold steady. A reading that climbs over the first 10 minutes is the motor running hot from a binding shaft.

Take a dissolved oxygen reading at the aeration chamber surface after 30 minutes of run time. NSF/ANSI 40 systems typically read 2-4 mg/L DO when healthy; anything below 1 mg/L means the aspirator is not drawing air - check for a kinked or blocked air intake screen on top of the motor housing.

Document and close out

• Norweco service log: aerator serial, install date, your service-provider ID number.
• State-required: in Florida (Chapter 64E-6.018 F.A.C.) and Indiana (327 IAC 6.1-2.4) submit the inspection report within the contract period.
• Warranty: Norweco aerators carry a 2-year parts warranty (residential) and 1-year labor when installed by a certified provider. Register at norweco.com within 30 days.
• Customer handoff: explain the green alarm light meaning, the audible silence button, the next required inspection date (varies by state - typically 6 or 12 months).

References

• Norweco Singulair Green Model 96 Installation and Service Manual, document SGI-96 Rev N (2024)
• NSF/ANSI 40-2023 - Residential Wastewater Treatment Systems
• Florida Administrative Code Chapter 64E-6.018 - Aerobic Treatment Unit Maintenance
• Indiana Administrative Code 327 IAC 6.1-2.4 - Residential Onsite Sewage Systems
• Norweco Service Bulletin SB-2024-03 - MSCB-001-AA Aerator Replacement
• US EPA Onsite Wastewater Treatment Systems Manual, EPA/625/R-00/008, Chapter 4