Ideal Standard / Armitage Shanks — 1/2″ Ceramic Disc Cartridge — HOT (Clockwise Close) — A963003NU
Genuine A963003NU quarter-turn (90°) ceramic cartridge for the HOT side (clockwise close) used on Ideal Standard / Armitage Shanks taps (e.g., Natos, Swan, Alto, Vectis).
Design update: latest OEM version is all-brass and handing is fixed (no longer user-adjustable). It still fits taps that used the earlier version.
Image 2: Left = earlier adjustable design (clip below the splines). Right = current OEM brass cartridge with fixed handing (A963003NU).
Key features
- Genuine Ideal Standard / Armitage Shanks A963003NU — HOT (clockwise close).
- 1/2″ quarter-turn ceramic disc valve (approx. 90° operation).
- Updated OEM design: brass body; handing is not adjustable.
- Photo reference: in Image 2, left shows the earlier adjustable version; right shows the updated brass, fixed-handing A963003NU.
- Typical fitments include Natos, Swan, Alto, Vectis, Opus, Tempo, Calista (selected models).
How to confirm HOT vs COLD
| Handle direction (to open) | Valve needed | Part code |
|---|---|---|
| Turns clockwise to open (closes anti-clockwise) | HOT (CO) cartridge | A963003NU (this item, FTB899) |
| Turns anti-clockwise to open (closes clockwise) | COLD (ACO) cartridge | A963004NU — FTB900 |
Tip: Don’t assume left = hot. Watch the lever direction on your tap to choose the correct handing.
Specification
- Type: 1/2″ quarter-turn ceramic disc cartridge
- Handing: HOT — clockwise close (CO)
- Overall length: ~57 mm
- Spline: 18 teeth (~7.6 mm Ø)
- Body: OEM brass (current design)
- Top screw: may not be supplied in current OEM packs
- Part code: A963003NU (HOT). Cold counterpart: A963004NU.
Known compatible tap families (examples)
- Natos / Swan (Ideal Standard)
- Alto (basin & bath pillar taps)
- Vectis (selected models)
- Opus, Tempo, Calista (selected 1/2″ quarter-turn models)
Model coverage varies by era/variant; if unsure, match the measurements and handing above.
What fails & typical symptoms
- Worn ceramic seats → dripping from spout when closed.
- Stiff or gritty action → limescale/debris inside the cartridge.
- Wrong handing fitted → lever turns the “wrong way” or won’t index correctly.
Fitting notes (at your own discretion)
- Isolate water. Protect the finish around the handle.
- Remove cap/screw & handle; lift off shroud if present.
- Unscrew retaining nut; withdraw old cartridge.
- Clean housing & seat; remove debris/limescale.
- Insert new A963003NU (HOT) aligned correctly; refit nut & trim.
- Restore water and test. If lever direction is wrong, you likely need the A963004NU (COLD) instead.
Work should be undertaken by a competent person. If unsure, consult a plumber.
Questions & Answers
Has the A963003NU design changed?
Yes. Ideal Standard updated the design to an all-brass body and handing is now fixed (no user hand-swap). It remains a direct fit for taps that used the earlier version.
How do I tell if I need HOT (A963003NU) or COLD (A963004NU)?
Watch which way the handle turns to open the water. If it opens with a clockwise turn, you need the HOT/CO valve (A963003NU). If it opens anti-clockwise, you need the COLD/ACO valve (A963004NU).
Will this fit my Natos / Swan / Alto / Vectis tap?
It fits many 1/2″ quarter-turn models in those families. Confirm by checking the ~57 mm length, 18-tooth (~7.6 mm) spline, and that your tap requires a clockwise-close (HOT) cartridge.
The old cartridge picture shows a clip below the splines — why is the new one different?
Older versions looked slightly different; the current OEM design supersedes them and still fits the same tap bodies. See Image 2 caption above for side-by-side reference.