Grundfos NB Pumps
Spare Parts for NB Range Pumps
Product Summary
Genuine and compatible spare parts for the Grundfos NB close-coupled end-suction pump (EN 733), used across Australia for HVAC chilled and condenser water, heating, water supply, irrigation and industrial transfer duties. Every NB from the NB 32-125.1 to the NB 125-250 uses the same build (single impeller, replaceable wear ring, mechanical shaft seal and standard IE3 motor), so tick what you need and we’ll match the exact kit to your nameplate (e.g. NB 65-160/149).
Spare Parts List
✓ Tick the parts you need. Grundfos NB service kits are matched to pump size, impeller diameter, materials and shaft seal code, so your nameplate model is all we need to get them right. Not sure which items? Add a photo of the nameplate and we’ll work out the kit for you.
| Select | Wear / Service Item | Function & when to replace |
|---|---|---|
| Common Service Kits | ||
| Shaft Seal Kit | Mechanical shaft seal with its fitting parts, matched to your seal code (standard BQQE: rubber bellows, SiC/SiC, EPDM; other faces and elastomers to order). Replace at the first sign of leakage behind the impeller. | |
| Impeller Kit | Impeller trimmed to your diameter (the number after the slash, e.g. /149) with its key, nut and washer. Replace if eroded, cracked or out of balance. | |
| Wear Ring Kit | The replaceable wear ring that seals the impeller eye. Worn rings let water recirculate and cost flow and head; renew them at any rebuild. | |
| O-ring & Gasket Kit | The O-ring between pump housing and cover plus plug seals, in EPDM or FKM. Renew whenever the pump is opened. | |
| Shaft Kit | Stainless pump shaft for your motor frame and pump size. Replace if the shaft is scored at the seal seat, bent or worn at the impeller fit. | |
| Other Core Parts | ||
| Replacement Motor | Standard IE3 motor matched to your kW, frame and speed (2-pole 2900 rpm or 4-pole 1450 rpm), from 0.37 to 45 kW across the range. | |
| Pump Housing | Cast iron volute casing with inlet and outlet flanges, matched to your pump size. Replace if cracked, badly corroded or eroded. | |
| Pump Cover & Motor Stool | The cover and adapter that join the pump end to the motor and house the shaft seal. Replace if cracked or damaged at the seal seat. | |
| Base Plate | Steel base frame for floor mounting of the larger NB sizes. We match it to your pump and motor frame. | |
| Complete Replacement Pump | When a rebuild doesn’t stack up, we quote a like-for-like NB from the model on your nameplate. | |
How we confirm the exact part: Grundfos NB kits depend on pump size, impeller diameter, material code, shaft seal code and motor frame. Your nameplate carries all of it, in the model (e.g. NB 65-160/149 A-F-A-BQQE) and the product number. Tick the items above and add a nameplate photo, and we’ll confirm the correct part and price for your exact pump.
Models
Spare parts are available for every NB size in the current Grundfos Australia range. In the model (e.g. NB 65-160/149), 65 is the outlet size (DN), 160 the nominal impeller diameter and 149 the actual impeller diameter in mm; a “.1” size is a reduced-performance version.
Models & Key Specifications
| Size | Casing sizes | Connections (in / out) | 2-pole kW (2900 rpm) | 4-pole kW (1450 rpm) |
|---|---|---|---|---|
| NB 32 | 125, 125.1, 160, 160.1, 200, 200.1 | DN50 / DN32 | 1.1–11 | 0.37–1.5 |
| NB 40 | 125, 160, 200, 250, 315 | DN65 / DN40 | 1.5–45 | 0.37–5.5 |
| NB 50 | 125, 160, 200, 250, 315 | DN65 / DN50 | 3–37 | 0.37–11 |
| NB 65 | 125, 160, 200, 250, 315 | DN80 / DN65 | 5.5–37 | 0.55–15 |
| NB 80 | 160, 200, 250, 315 | DN100 / DN80 | 15–37 | 1.5–22 |
| NB 100 | 200, 250, 315 | DN125 / DN100 | — | 4–30 |
| NB 125 | 250 | DN150 / DN125 | — | 11–30 |
All sizes: liquid temperature −25 °C to +120 °C (clean water / glycol), PN16 DIN flanges, standard shaft seal BQQE (others on request), IE3 IP55 motors, 50 Hz. Cast iron housing, stainless impeller, AISI 304 shaft, brass wear ring. Variable speed NBE available on request.
Troubleshooting
Pump will not start
Likely cause: no supply, a tripped motor protection or fuse, or a seized pump. Action: check the supply and reset the protection; with the power isolated, turn the shaft by hand. A pump that won’t turn needs inspection of the impeller, wear rings and seal.
Motor protection trips repeatedly
Likely cause: overload from running well right of the duty curve (low system resistance), a rubbing impeller, failing bearings or a phase fault. Action: check the voltage on all phases and the motor current; throttle to the duty point; inspect the impeller and bearings; confirm the impeller diameter suits the duty.
Low flow or head
Likely cause: worn wear rings or impeller, air in the pump, a blocked suction strainer or impeller, wrong rotation. Action: vent the pump and check the suction side; clean the strainer and impeller; confirm rotation; if output still falls short, replace the wear ring kit and impeller kit.
Noise or vibration
Likely cause: cavitation (insufficient NPSH), air in the pump, a damaged or out-of-balance impeller, worn bearings, or pipe strain on the flanges. Action: check suction pressure and NPSH; vent the pump; inspect the impeller and bearings; support the pipework so the pump isn’t carrying it.
Leaking at the shaft seal
Likely cause: worn or damaged seal faces, often from dry running, abrasive particles or a seal material that doesn’t suit the liquid. Action: replace the shaft seal kit and renew the O-rings. Never run a NB dry: the seal relies on the pumped liquid for cooling and lubrication.
Leaking at the pump housing
Likely cause: a perished O-ring between the pump housing and cover, a failed flange gasket, or a cracked housing. Action: fit the O-ring and gasket kit and tighten the housing bolts evenly to Grundfos specification; replace the housing if it is cracked.
Pump runs backwards after stopping
Likely cause: a leaking or missing non-return valve on the discharge. Action: repair or replace the non-return valve. Reverse spin can damage the seal and loosen the impeller.
Request for Quotation
Selected Parts:
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Not sure which parts? Just send a photo of the nameplate or part below.