Astralpool Controller Viron P320C & Label SP21488
Astralpool Controller Viron P320C & Label SP21488 is temporarily out of stock and will ship as soon as it's available.
Don't Guess - Ask Us!
Don't Guess - Ask Us!
Not sure if it’s the right part? Send us a message and a photo of what you’re replacing, or what you need, and we’ll help make sure you get the right part the first time.
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Delivery and Shipping Info*
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Astralpool Controller Viron P320C & Label SP21488
Astralpool Controller Viron P320C & Label SP21488 is temporarily out of stock and will ship as soon as it's available.
Astralpool Controller Viron P320C & Label SP21488
This is the genuine Astralpool variable speed controller for the Viron XT P320, supplied with its label. Astralpool lists the controller as 21488 for the P320 and 21489 for the P520 — the two are not interchangeable, because each is matched to its own motor output.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
The Viron XT Part Matching Rule (rev. VXP-1.0)
Controllers are the single easiest Viron part to order wrongly, because the pump body looks identical across the range. Confirm all three of these before ordering:
- Model number — P320 or P520. The P320 runs a 0.75 kW motor at 4.1 amp; the P520 runs 1.5 kW at 6.0 amp. Astralpool warns that fitting a 1 HP control to a 2 HP motor causes the HI A over-current fault.
- Generation — XT, XT Series 2, or C XT. The controller housing and rear cover changed across these. Read the full badge, not just the number.
- Photograph the existing controller and its label before ordering. The label carries the identifying detail we need if there is any doubt.
If your pump badge says eVo rather than XT, this is the wrong controller entirely — that is a different pump generation. Send us a photo and we will identify the correct part.
Related Viron XT Control Parts
- 21488 — controller, P320 (this product)
- 21489 — controller, P520
- LABEL311 — controller label
- LABEL518 — XT label
- 70603 — controller rear cover
- 40145 — rear cover retaining screws (x2)
- SP12812 — display screen, Viron XT P320 (buy here)
- SP71660 — motor with slinger, Viron XT P320 (buy here)
Symptoms of Controller Failure
- Blank or partially lit display with power confirmed at the outlet
- Pump unresponsive to the speed buttons, or stuck at one speed
- Timer settings not holding through a power cycle
- Persistent fault codes with no mechanical cause found — HI T (over temperature), HI A (over current), LO V (under voltage) or BSUC (motor stuck)
- No communication with a connected chlorinator, EQ doser or Viron Connect over the RJ12 data cable
Before replacing a controller, note that Viron pumps hold power in their circuit boards. Astralpool advises turning power off completely for ten seconds before switching back on, and some non-Astralpool chlorinators bleed a small current into the pump even when off, which can stop it resetting correctly. Rule that out first — it presents exactly like a dead controller.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers or diagrams? See the manufacturer catalogues: Astralpool Catalogue 2026 | Zodiac Catalogue 2026
Before ordering: confirm this part is correct for your pump. Use the catalogues above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers and any labels. All electrical work must be carried out by a licensed electrician in accordance with AS/NZS 3000. This is a special-order item.
Common search terms: Astralpool SP21488, Viron P320 controller, Viron XT P320 controller, 21488 controller, Astralpool variable speed pump controller, Viron P320C controller replacement.
In plumbing, named sizes are not the actual measurements. A pipe called “50mm” or “2"” does not measure 50 mm across. Instead, it follows nominal sizing, an internationally-standardised naming system.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
These are nominal sizes and are designed to fit matching fittings — not to measure exactly what their name suggests. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate. Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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SP21488