Heat Pump Barrel Union - AstralPool, EvoHeat, Fairland, Hayward, Henden, Madimack, Pentair, PHNIX, Sensaheat, SpaNET, SpaPro, WWDG
Heat Pump Barrel Union - AstralPool, EvoHeat, Fairland, Hayward, Henden, Madimack, Pentair, PHNIX, Sensaheat, SpaNET, SpaPro, WWDG - is backordered and will ship as soon as it is back in stock.
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
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Heat Pump Barrel Union - AstralPool, EvoHeat, Fairland, Hayward, Henden, Madimack, Pentair, PHNIX, Sensaheat, SpaNET, SpaPro, WWDG - is backordered and will ship as soon as it is back in stock.
Heat Pump Barrel Union plumbing connection to suit many pool and spa heat pumps, including many units from Aquark, Aquatermic, AstralPool, Chilli, EvoHeat, Fairland, Hayward, Heatseeker, Henden, Madimack, Oasis, Pentair, PHNIX, Raypak, Relteck, Rheem, Sensaheat, SpaNET, SpaPro, Sunlover, Sunrain, Supreme, Waterco and WWDG, plus many other rebadged heat pumps. This style of barrel union is commonly used across a large range of modern heat pumps that share the same plumbing connection design.
Kept Physically in Stock for Pick up or Fast Shipping
Please check the thread style shown in the product photos, along with measurements and dimensions, before ordering. There are a number of similar-looking heat pump unions on the market, so photo matching, thread style, and sizing are important.
Some early heat pumps used odd plumbing sizes where the pipe glues in. This is the more common and more universal style, designed to suit 40mm PVC pressure pipe and 50mm pressure fittings / sockets. Please see the notes and dimensions below.
Dimensions & Specifications
- Nut thread internal diameter: approx. 72mm
- Nut-side tail outside diameter: approx. 75mm (the part typically visible on the heat pump)
- Glued socket outside diameter: approx. ~60-61mm (to suit 50mm pressure sockets)
- Glued socket internal diameter: approx. 48mm (to suit 40mm pressure PVC pipe)
PVC pressure pipe dimensions are often different from the nominal size they are sold under. See here for an explanation of PVC plumbing sizes and naming.
Common Associated Part Numbers
20000-130096, 20000-130097, SH-19314, HP-UNION-FITT, SH-HPUNION, DS44, HWX200130097
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" | 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.
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).
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) |
|---|---|---|
| 1/2" | 15 mm | ~21.2–21.5 mm |
| 3/4" | 20 mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 32 mm | ~42.1–42.4 mm | |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 65 mm | ~75.2–75.5 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.
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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