Balboa BP21P4BC Controller – 3.0kw
Balboa BP21P4BC Controller – 3.0kw is backordered and will ship as soon as it is back in stock.
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Don't Guess - Ask Us!
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Delivery and Shipping Info*
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Balboa BP21P4BC Controller – 3.0kw
Balboa BP21P4BC Controller – 3.0kw is backordered and will ship as soon as it is back in stock.
Balboa BP21P4BC Controller. There are multiple variations of BP21 spa packs and they are not necessarily cross compatible. Ensure you are purchasing the exact/compatible spa pack. Model variations include: BP2100G0, BP2100G1, NHP2100H, BP21P4BC, Microsilk variations. NO pack suits Microsilk unless specified. Programming must be set PRIOR to connection any 2 speed pump.
GL8000, EL8000 Replacement:
Commonly used to replace GL8000, EL8000 control packs. Note that button functions on touchpad may change. Eg: 1 x button pressed twice might activate 2 pumps. We recommend engaging a Spa Technician when replacing the above control packs.
- Confirm compatibility by reviewing the tech sheet and your equipment.
BP21P4BC 240volt Output Sockets
CPUMP: Circ pump (must have a circ pump if pump 1 single speed)
PUMP 1: 1Spd Pump or 2Spd Pump
PUMP 2: 1Spd Pump or 2Spd Pump
PUMP 3: 1Spd Pump
PUMP 4: 1Spd Pump
BLOWER: Blower
240V: This outlet has a constant 240volts and is not switchable
O3/UV: This outlet is only to be used with an ozone system
BP21P4BC Low Voltage
2 x Touchpad Outlets
1 x AUX Outlet
1 x Light
1 x Wifi Port
BP21P4BC Features
*In heater temp sensors
*Max Temp 40 degrees
*Adjustable Filtration
*Heater Modes (Ready & Rest)
*Wifi Interface
*Programmable Load Shedding
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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