Water System Parts - Zodiac JXI / Astralpool IXI Gas Heater Parts

Imperial Name	Metric Name	Pipe Diameter (OD)
1"	25 mm	~33.4–33.7 mm
1.5"	40 mm	~48.1–48.4 mm
2"	50 mm	~60.2–60.5 mm
2.5"	65 mm	~75.2–75.5 mm

Imperial Name

Metric Name

Pipe Diameter (OD)

25 mm

~33.4–33.7 mm

1.5"

40 mm

~48.1–48.4 mm

50 mm

~60.2–60.5 mm

2.5"

65 mm

~75.2–75.5 mm

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.

Quick example: A 2" / 50 mm fitting is named for the pipe it connects to, but the pipe’s actual outside diameter (OD) is approx. 60.3 mm (typically ~60.2–60.5 mm in AS/NZ pressure pipe).

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).

Important: For pool/spa work, most plumbing uses Pressure Pipe (AS/NZ standards) — not DWV. Always check OD and the pipe class against your equipment specifications.

PVC Pressure Pipe AS/NZ 1477 Dimensions¹:

Common nominal sizes with typical outside diameters and indicative inside diameters by class.

Imperial Name	Metric Name	Outside Diameter (OD)	Class 9 IDº	Class 12 IDº	Class 18 IDº
1/2"	15 mm	~21.2–21.5 mm		18.3 mm	17.8 mm
3/4"	20 mm	~26.6–26.9 mm		23.7 mm	22.4 mm
1"	25 mm	~33.4–33.7 mm	30.5 mm	29.8 mm	28.1 mm
	32 mm	~42.1–42.4 mm	38.5 mm	37.5 mm	35.4 mm
1.5"	40 mm	~48.1–48.4 mm	45.2 mm	44.1 mm	42.8 mm
2"	50 mm	~60.2–60.5 mm	55.2 mm	53.7 mm	50.5 mm
	65 mm	~75.2–75.5 mm	68.9 mm	67.0 mm	63.2 mm
2.5"		~73 mm

Imperial Name

Metric Name

Outside Diameter (OD)

Class 9 IDº

Class 12 IDº

Class 18 IDº

1/2"

15 mm

~21.2–21.5 mm

18.3 mm

17.8 mm

3/4"

20 mm

~26.6–26.9 mm

23.7 mm

22.4 mm

25 mm

~33.4–33.7 mm

30.5 mm

29.8 mm

28.1 mm

32 mm

~42.1–42.4 mm

38.5 mm

37.5 mm

35.4 mm

1.5"

40 mm

~48.1–48.4 mm

45.2 mm

44.1 mm

42.8 mm

50 mm

~60.2–60.5 mm

55.2 mm

53.7 mm

50.5 mm

65 mm

~75.2–75.5 mm

68.9 mm

67.0 mm

63.2 mm

2.5"

~73 mm

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.

Imperial Name	Metric Name	Inside Diameter (ID)
3/8"	9–10 mm	~9 mm
3/4"	19 mm	~19 mm

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

BSP Thread Size Naming

Outside Diameter (mm / inch)

TPI

1/16" BSP

7.7 mm / 0.304"

1/8" BSP

9.7 mm / 0.383"

1/4" BSP

13.16 mm / 0.518"

3/8" BSP

16.66 mm / 0.656"

1/2" BSP / 15 mm

20.99 mm / 0.825"

5/8" BSP

22.99 mm / 0.902"

3/4" BSP / 20 mm

26.44 mm / 1.041"

7/8" BSP

30.20 mm / 1.189"

1" BSP / 25 mm

33.25 mm / 1.309"

1-1/4" BSP

41.91 mm / 1.650"

1-1/2" BSP / 40 mm

47.80 mm / 1.882"

2" BSP / 50 mm

59.61 mm / 2.347"

2-1/4" BSP

65.71 mm / 2.587"

2-1/2" BSP

75.18 mm / 2.960"

3" BSP

87.88 mm / 3.460"

4" BSP

113.03 mm / 4.450"

5" BSP

138.43 mm / 5.450"

6" BSP

163.83 mm / 6.450"

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We stock and supply parts from all the major brands: Aeware, AquaFlo, Astralpool, Balboa, CG Air, CMP, Darlly, Davey, Del Ozone, Edgetec, EvoHeat, Fluidra, Gecko, Hurlcon, Jandy, LX, Pentair, Raypak, Rheem, SpaNet, Spa-Quip, Waterco, Waterway, Zodiac—and many more.
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Please note: Images are for illustration only—actual products may vary. Some OEM parts may arrive without packaging or manuals. Where available, manuals are on the product page or provided on request. All parts must be installed by qualified professionals. Electrical and gas work must be carried out by licensed technicians.
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Water System Parts - Zodiac JXI / Astralpool IXI Gas Heater Parts

Delivery and Shipping

Understanding Plumbing Sizes & Nominal Measurements

Why pipe sizes don’t match the measurements

How to Measure Pipe Correctly

Hose & Tube Dimensions

BSP – British Standard Pipe Thread Sizes

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