Direct answer: North Star NSC22 and NSC31 softeners share one parts list built around a 3/4-inch valve; the NSC42 has its own list for a 1-inch valve. All three use the same resin, part 0502272 (1 cubic foot), the same brine tank (7391305), brine valve (7381180) and 24V DC power supply (7351054). The manuals say to order repair parts through [email protected]; warranty parts go through the installing contractor. Aftermarket, used or non-manufacturer parts void all warranties.
Publisher boundary: Water System Guide is an independent research publisher, not a North Star dealer or parts seller. Part numbers are copied from manual 7393624 (NSC22 and NSC31) and manual 7393632 (NSC42), both Rev. H dated January 7, 2026, reviewed October 15, 2026. We list no prices and do not confirm availability. NST, NSCWC and NSCWHC systems have their own documents.
Confirm the model first
Read the rating decal, then check the model code the control displays at power-up: n22P (NSC22), n31P (NSC31) or n42P (NSC42) (NSC31 manual, PDF page 12). The NSC22 and NSC31 are documented in one manual and share every part number in its lists, including the resin tank. The NSC42 differs in its valve, control board, faceplate, salt lid and resin tank.
Keep the small parts that ship with the softener. The NSC22/NSC31 packing list includes clips, hose clamps, an adaptor elbow, the bypass valve, a drain hose, a grommet, silicone grease and a water hardness test strip (NSC31 manual, PDF page 5). The silicone grease is what the manual specifies for O-rings during service.
Resin and resin tank
| Part | NSC22 / NSC31 | NSC42 |
|---|---|---|
| Resin, 1 cu. ft. | 0502272 | 0502272 |
| Replacement resin tank | 7113058 (8 x 40 in.) | 7247996 (10 x 40 in.) |
| Top distributor | 7077870 | 7077870 |
| Replacement bottom distributor | 7327584 | 7327584 |
| Distributor O-ring kit | 7112963 | 7112963 |
| Tank neck clamp kit | 7331177 | 7331177 |
Sources: NSC22/NSC31 parts list, PDF page 25; NSC42 parts list, PDF page 25.
The resin quantity differs by model even though the part number is the same. The specification tables list 0.65 cubic feet for the NSC22, 0.81 for the NSC31 and 1.20 for the NSC42 (NSC31 manual, PDF page 3). By our arithmetic, the NSC22 and NSC31 each fit within one 1-cubic-foot unit; the NSC42 needs more.
The manuals give no owner procedure for rebedding. Their troubleshooting table points to the tank assembly instead: “resin in household plumbing” means a crack in the distributor or riser tube, corrected by replacing the resin tank assembly. Iron fouling is handled with resin bed cleaner, not new resin. The fiberglass resin tank has a 10-year limited warranty.
Valve parts
| Part | NSC22 / NSC31 (3/4-inch) | NSC42 (1-inch) |
|---|---|---|
| Nozzle and venturi kit | 7398674 | 7398705 |
| Retainer, nozzle and venturi | 7081201 | 7081201 |
| O-ring, 1/4 x 3/8 in. (pack of 2) | 7342649 | 7342649 |
| Seal kit | 7129716 | 7185487 |
| Rotor and disc | 7199232 | 7185500 |
| Wave washer | 7082087 | 7175199 |
| Valve body | 7082053 | 7171145 |
| Valve cover | 7337466 | 7171161 |
| Motor, cam and gear kit | 7397864 | 7384691 |
| Position switch | 7030713 | 7305150 |
| Drain hose adaptor kit (with 2.0 gpm flow plug) | 7331185 | 7331169 |
| Drain plug kit | 7342665 | 7342712 |
| Turbine and support assembly | 7113040 | 7290931 |
| Sensor wire harness | 7309803 | 7309811 |
Sources: NSC22/NSC31 valve parts, PDF page 27; NSC42 valve parts, PDF page 27.
Clean the nozzle and venturi before replacing it
The manuals call a clean nozzle and venturi “a necessity for the water softener to work properly,” because it creates the suction that moves brine into the resin tank; if sand, silt or dirt plugs it, “the water softener will not work, and hard water will result” (NSC31 manual, PDF page 19). Cleaning is an owner task: put the bypass in bypass with the softener in service, unscrew the cap while holding the housing, lift out the screen support and screen, remove the disc, gasket and flow plug, wash them in warm soapy water and reassemble with the gasket’s small hole centered over the housing’s. Hand-tighten the cap.
Control, cabinet and brine parts
| Part | NSC22 / NSC31 | NSC42 |
|---|---|---|
| Replacement electronic control board | 7360867 | 7369798 |
| Electronics enclosure, rear | 7391729 | 7391729 |
| Faceplate | 7391559 | 7391567 |
| Faceplate decal | 7393496 | 7393501 |
| Salt lid | 7391494 | 7393721 (with magnet) |
| Top cover | 7391444 | 7391444 |
| Power supply, 24V DC | 7351054 | 7351054 |
| Brine tank | 7391305 | 7391305 |
| Brinewell | 7137824 | 7137824 |
| Rim | 7391355 | 7391355 |
| Brine valve assembly | 7381180 | 7381180 |
| Overflow hose adaptor kit | 7331258 | 7331258 |
| Drain hose | 7139999 | 7139999 |
The NSC42’s salt lid is listed “with magnet.” The manual explains why: its tank light comes on whenever the salt lid is opened and turns off when it closes, or after 15 minutes if the lid is left open (NSC42 manual, PDF page 17). The NSC22 and NSC31 use a TANK LIGHT button instead.
Bypass and connection parts
| Part | NSC22 / NSC31 | NSC42 |
|---|---|---|
| Bypass valve assembly | 7370286 (3/4 in., with 2 O-rings) | 7214383 (1 in., with 2 each clips and O-rings) |
| Clip, single | 7116713 (2 required) | 7089306 (4 required) |
| Clip, pack of 20 | 7336397 | 7336428 |
| O-ring, single | 7170288 (15/16 x 1-3/16 in., 2 required) | 7311127 (1-1/16 x 1-5/16 in., 4 required) |
| O-ring, pack of 20 | 7336402 | 7336410 |
| Installation adaptor, single | Not listed | 7271204 (2 required) |
| Installation adaptor, pack of 10 | Not listed | 7336614 |
The manuals warn that improper removal can damage the large holding clips and that damaged clips should not be reinstalled. Have spares before disconnecting the softener.
Brine-side problems and the parts behind them
A salt tank full of water is a common reason to look for parts. The troubleshooting table lists seven causes for “no soft water and salt storage tank full of water” (NSC31 manual, PDF page 20). Several are not parts at all: a plugged or kinked drain hose, a valve drain and tank overflow joined by a tee, or low or high water pressure. The parts-related causes are a dirty or damaged nozzle and venturi, an inner valve leak (seals and rotor), a dirty or broken brine float (clean or replace the brine valve float assembly), and a leak between the valve and resin tank (the O-rings in distributor kit 7112963). Rule out the plumbing causes first.
Problems no softener part will fix
Before ordering valve or resin parts for stained or cloudy water, check what the softener is designed to remove. The manuals’ “Water Conditioning Information” page separates four types of iron and sediment (NSC31 manual, PDF page 5):
- Ferrous (clear-water) iron dissolves in water. The softener “will reduce moderate amounts,” up to the model’s rated limit: 6 ppm for the NSC22, 8 ppm for the NSC31 and 11 ppm for the NSC42. Add 5 to the hardness setting for each 1 ppm.
- Ferric (red-water) iron and bacterial or organically bound iron are insoluble. “This water softener will not remove ferric or bacterial iron”; filtration is the usual approach, with chlorination recommended for bacterial iron.
- Colloidal iron “will not filter or exchange out of water,” and the softener will not remove it.
- Sediment such as clay or silt is not removed either. The manual says “a sediment filter installed upstream of the water softener normally corrects this situation.”
If the problem is one of these, a new nozzle, seal kit or resin will not cure it, and fouling can return. North Star sells separate iron and sediment filtration products; ask the contractor which fits a tested water sample.
How to order and what the warranty covers
Each parts list ends with “To order repair parts, contact us at: [email protected].” For warranty parts, the manual’s process starts with the contractor: “Should a defect or malfunction occur, contact your contractor.” If that is not possible, return the part freight prepaid to the factory with a description of the problem, your name and address, the purchase date, model and serial numbers, and the selling contractor’s name and address (NSC31 manual, PDF page 28).
The warranty terms that apply to parts:
- One year on all parts.
- Five years on the electronic control board and valve body.
- Ten years on the salt storage tank and fiberglass resin tank.
- Defective parts in those periods are shipped to the home without charge.
- Aftermarket, used or non-manufacturer parts void all warranties.
The manual’s warranty does not include a labor term. Ask the contractor what labor their installation covers. Our who makes North Star softeners page explains why the same manufacturer’s Rheem-branded softeners share several of these part numbers, and our error code guide maps codes to the switch, motor and board.
Frequently asked questions
What resin does a North Star water softener use?
The NSC22, NSC31 and NSC42 manuals all list resin part 0502272, sold by the cubic foot. The softeners hold 0.65, 0.81 and 1.20 cubic feet respectively.
What is the North Star nozzle and venturi part number?
The NSC22 and NSC31 use kit 7398674 and the NSC42 uses 7398705. The manuals describe cleaning the existing nozzle and venturi first.
Where do I order North Star softener parts?
The manuals say to contact [email protected] to order repair parts. For warranty parts, contact the installing contractor first.
How long is the North Star parts warranty?
One year on all parts, five years on the electronic control board and valve body, and ten years on the salt and resin tanks, from the delivery date.