Balboa M7 Heater Temperature Sensor - sNA, SA, sNB, SB Error Fix - 12" / 14" / 24"
Balboa M7 Heater Temperature Sensor - sNA, SA, sNB, SB Error Fix - 12" / 14" / 24" is temporarily out of stock and will ship as soon as it's available.
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Balboa M7 Heater Temperature Sensor - sNA, SA, sNB, SB Error Fix - ...
Balboa M7 Heater Temperature Sensor - sNA, SA, sNB, SB Error Fix - 12" / 14" / 24" is temporarily out of stock and will ship as soon as it's available.
Balboa M7 Heater Temperature Sensor - sNA, SA, sNB, SB Error Fix - 12" / 14" / 24"
Genuine Balboa M7 Temperature / Hi-Limit Sensor. This sensor is used in many Balboa M7 spa control systems where two matching sensors are fitted into the heater tube to monitor water temperature, heater temperature and flow conditions.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
- Genuine Balboa part, not a generic copy.
- Used for both temperature and hi-limit sensing on M7 heater systems.
- Commonly used in Balboa GS, GL, BP and Revolution style control systems.
Balboa M7 Sensor Details
- Connector: 2-pin plug for Balboa circuit boards
- Probe diameter: approximately 6.3mm / 1/4 inch
- Function: temperature sensor and hi-limit sensor, depending on position and system
- Common error codes: Sn, SA, Sb, OH, HH, dry heater, heater may be dry, sensor balance errors
- Sensor type: 30k NTC thermistor
- Resistance: approximately 30kΩ at 25°C
What This Sensor Does
Balboa M7 systems generally use two identical sensors, one at each end of the heater tube. The control box compares the readings from both sensors to monitor spa water temperature, heater temperature and water flow through the heater.
If one sensor is faulty, drifting, open-circuit, shorted or reading differently from the other sensor, the spa may show sensor, overheat or dry heater errors even when the heater tube is full of water.
When To Replace Balboa M7 Sensors
This sensor may be required if your Balboa spa control system is showing faults such as Sn, SA, Sb, OH, HH, dry, dr, dRY, heater may be dry, sensor balance or unexplained heating shutdowns.
In many cases it is best to replace both M7 sensors at the same time, especially on older systems, because the spa controller relies on the two sensors reading closely together.
Important Before Ordering
- Check the cable length of your existing sensor before ordering.
- Some Balboa M7 sensors are the same electrically but have different cable lengths.
- Make sure the sensor probe, plug and cable length match your existing sensor.
- This is not a pressure switch. M7 systems use temperature sensors to help detect flow through the heater.
Common Balboa Part Numbers
Depending on cable length and version, Balboa M7 sensors may be associated with part numbers including 30344, 53605, 32016, 30382, 30514, 25283 and other superseded or spa-brand-specific numbers. Always compare the plug, probe and cable length before ordering.
Common Compatibility Guide
This sensor type is commonly used on Balboa M7 heater and control systems, including many systems in the following ranges. This is a guide only and is not a complete list of every compatible spa or control box.
- Balboa GS Series: commonly seen on GS100, GS500, GS500Z, GS501, GS501Z, GS510, GS511, GS520, GS523 and other GS M7 systems
- Balboa GL Series: commonly seen on GL2000, GL800, GL1200 and other GL M7 systems, but check carefully as some GL systems use different sensor arrangements
- Balboa BP Series: commonly seen on BP200, BP501, BP601, BP7, BP2100 and other BP M7 systems
- Balboa Revolution Series: used on some Revolution control systems with M7 heater sensing
- Balboa Value / LE / SUV Systems: some 1000LE, 2000LE, 2000 Value and SUV systems use M7 sensors, but cable length and version must be confirmed
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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