XMK 6600-166 Temperature Sensor for Sundance Spas and Jacuzzi Hot Tubs, with Curled Finger Connectors and 6540-228 O-Ring
- Compatibility: 6600-166 spa temperature sensor with curled finger connectors compatible with Sundance Spas.
- Temperature Sensor for Jacuzzi Hot Tub Models: All J300-J365 tubs use the 6600-066 curled finger sensor.
- Temperature Sensor for Sundance Spas Models: 2012+ 680 Peyton, 2011+ Select Series 2008+ 680 Denali.
- Temp Sensor for Sundance Spas Models: 1998-2004 Sweetwater Series and Portofino Series: Caprio, Metro and.
Hot Tub Sensor-Compatible with Balboa Spa Heater M7 System 30344 30042 30382, 24" Temp/Hi-Limit, 1/4" Dia Dual Purpose Sensor Hot
- All spa parts hot tub temperature sensor, Replacement for Balboa spa M7 heater sensor 53605,32016,30042.
- KEYDINHT M7 temperature sensor for hot tub is a reliable tool for accurately measuring water temperature.
- KEYDINHT The bal'boa m7 sensor uses 12 feet of sensing wire, facilitating the movement and connection of.
- Cut off old bal'boa heat sensor 30344 Temp/Hi Limit Sensor in the hot tub and tape old wire to new spa.
A hot tub bubbling but failing to heat indicates a specific problem within its heating system. This symptom typically points to a faulty heater element, a malfunctioning temperature sensor, or restricted water flow. These three causes account for most instances where the pump and air blower appear to work, but the water remains cold.
Finding the exact cause requires a systematic approach. You can often diagnose and fix these problems yourself, avoiding a costly service call. Check for Restricted Water Flow
The most common reason a hot tub heater fails to engage, even with the jets bubbling, is inadequate water flow. Hot tub heaters have safety switches that prevent them from operating without sufficient water circulation. This protects the heater element from overheating and burning out. Bubbling jets mean the pump is running, but the flow through the heater itself might be too low.
What to Check:
- Water Level: The hot tub water level must be above the skimmer opening. If the water is too low, the pump can draw air, reducing flow and potentially causing an airlock. Top off the water if needed.
- Dirty Filter Cartridge: A clogged or dirty filter is a primary culprit for restricted flow. Over time, debris, oils, and minerals accumulate, making it harder for water to pass through. This reduces the pressure reaching the heater.
- Quick Test: Remove the filter cartridge entirely. Turn the hot tub power back on. If the heater begins to work, the filter was the problem.
- Solution: Clean or replace the filter cartridge. Cleaning involves rinsing with a hose and using a specialized filter cleaning solution.
- Closed or Partially Closed Valves: Many hot tubs have gate valves or ball valves on the plumbing lines leading to and from the heater or pump. Make sure all valves are fully open. Sometimes, they are accidentally bumped or left partially closed after maintenance.
- Airlock in the Pump: An airlock can occur if air gets trapped in the pump housing, preventing water from circulating properly. Even if the pump motor hums, no water moves.
- Quick Test: Look for a small bleeder valve on top of the pump housing. Loosen it slightly to release trapped air. You should hear a hiss of air followed by a trickle of water. Tighten the valve once water flows steadily.
- Alternative: Turn off the power, loosen a union fitting on the discharge side of the pump until water seeps out, then retighten. This allows trapped air to escape.
- Debris in Plumbing: Less common, but sometimes small objects or excessive scale can build up inside the plumbing lines, creating an obstruction. This usually requires a technician to diagnose and clear.
Repair Costs for Flow Issues:
Most flow issues are DIY fixes and cost nothing beyond your time. A new filter cartridge can cost $30-$80. If a professional needs to clear a stubborn airlock or plumbing obstruction, expect to pay for a service call and an hour or two of labor, totaling $150-$300.
2. Troubleshoot the Temperature Sensors
Hot tubs use multiple sensors to monitor water temperature and ensure safe operation. There is usually a primary temperature sensor and a hi-limit sensor. If either of these malfunctions, the control system might incorrectly believe the water is already hot, or it might prevent the heater from turning on due to a perceived overheating condition.
The bubbling action of the jets means the control panel is receiving power and engaging the pump, but it is not activating the heater. This often points to a sensor reading issue.
Understanding Hot Tub Sensors:
- Temperature Sensor: This sensor reads the actual water temperature and communicates it to the control board. The board uses this information to determine when to activate the heater to reach your set temperature.
- Hi-Limit Sensor: This is a safety sensor. It monitors for dangerously high water temperatures or heater overheating. If it detects a temperature above a safe threshold (e.g., 110-120°F), it shuts down the heater and sometimes the entire spa to prevent damage or injury.
What to Check:
- Error Codes: Check your hot tub's control panel for any error codes. Common codes like 'SN1', 'SN2', 'HL', 'OH', or variations indicate sensor problems or overheating. Consult your owner's manual for specific code meanings.
- Visual Inspection: Turn off the power to the hot tub. Locate the sensors, which are typically inserted into wells in the heater tube or plumbing. Look for obvious damage, corrosion, or loose connections.
- Resistance Testing (Advanced): If you have a multimeter, you can test the sensor's resistance (ohms). The resistance changes with temperature.
- Disconnect the sensor from the control board.
- Set your multimeter to measure ohms.
- Place the probes on the sensor's terminals.
- Compare the reading to the manufacturer's specifications for your specific sensor model and the current water temperature. Turn off the power, drain the hot tub if necessary (depending on sensor placement), disconnect the old sensor, and install the new one.
- For Sundance Spas and Jacuzzi Hot Tubs, the XMK 6600-166 Temperature Sensor is a common replacement. It features curled finger connectors and often includes the 6540-228 O-Ring. This sensor is compatible with Sundance Spas 2012+ 680 Peyton, 2011+ Select Series, and 2008+ 680 Denali models. For Jacuzzi J300-J365 tubs, the 6600-066 curled finger sensor is used.
- If your hot tub uses a Balboa M7 heater system, consider a Hot Tub Sensor-Compatible with Balboa Spa Heater M7 System. These sensors are designed for accurate temperature measurement and are compatible with Balboa models like 53605, 32016, 30042, 30344, 30042, and 30382.
Repair Costs for Sensors:
New temperature sensors typically cost $20-$80. If you do it yourself, this is your only expense. A professional sensor replacement, including the part and labor, might range from $150-$300.
3. Inspect the Heater Element
Even if water flows correctly and sensors report accurate temperatures, a hot tub will not heat if the heater element itself is defective. The heater element is essentially a large, specialized electrical coil that heats the water as it passes through. If it burns out or breaks, it cannot generate heat.
What to Check:
- Visual Inspection: Turn off the power to the hot tub. Drain the hot tub to below the heater tube level. Remove the access panel to the equipment compartment. Locate the heater tube, which is usually a metal cylinder in the plumbing line. Look for signs of corrosion, discoloration, or scale buildup on the heating element terminals or inside the tube. A burned-out element might show obvious charring or a break in the coil.
- Continuity Test (Advanced): Use a multimeter to test for continuity across the heater element terminals.
- Safety First: Make sure the hot tub is completely disconnected from power at the breaker before touching any electrical components.
- Disconnect the wires leading to the heater element terminals.
- Set your multimeter to the continuity setting (usually indicated by a speaker symbol or ohms).
- Place one probe on each heater terminal.
- A working element will show continuity (a beep or a low resistance reading, typically 9-12 ohms for a 4kW element or 3-4 ohms for a 5.5kW element). If the multimeter shows no continuity (an open circuit or 'OL'), the element is burned out and needs replacement.
- Check for Tripped Breaker: While less likely if the pump and jets are working, sometimes the breaker specifically for the heater circuit can trip. Check your main electrical panel for a tripped breaker related to the hot tub.
Replacing a Heater Element:
Replacing a heater element involves draining the spa, disconnecting electrical wires, unbolting the old element, and installing the new one. It requires careful attention to electrical safety and plumbing seals. If you are uncomfortable with electrical work, hire a qualified technician.
For more detailed troubleshooting on heating issues, refer to our Hot Tub Not Heating: Causes & Quick Fixes guide.
Repair Costs for Heater Element:
A new heater element typically costs $150-$400, depending on the hot tub brand and wattage. DIY replacement saves on labor. Professional replacement, including the part and labor, can range from $250-$600.
4. Control Panel or Circuit Board Malfunction
If you have ruled out flow issues, sensor problems, and a faulty heater element, the control panel or main circuit board might be the cause. These components manage all functions of the hot tub, including sending power to the heater based on sensor input and user settings.
What to Check:
- Visual Inspection: With the power off, inspect the circuit board for any signs of burning, corrosion, or damaged components. Look for scorch marks around relays that control the heater.
- Reset the System: Sometimes, a simple power cycle can resolve a temporary glitch. Turn off the power to the hot tub at the breaker for 15-30 minutes, then turn it back on.
- Professional Diagnosis: Diagnosing a faulty circuit board often requires specialized knowledge and tools. If you suspect a board issue, it is best to consult a certified hot tub technician. They can test voltage outputs and communication signals to confirm the problem.
Repair Costs for Control Board:
A new hot tub control board can be expensive, ranging from $300-$800 for the part alone. Professional diagnosis and replacement can push the total cost to $500-$1200 or more, making it one of the most expensive repairs.
Preventative Maintenance Tips
Regular maintenance can significantly reduce the likelihood of your hot tub bubbling but not heating. Proactive steps keep the system running efficiently and extend the life of components.
- Clean Filters Regularly: Rinse your filter cartridges every 2-4 weeks and deep clean them with a chemical solution every 3-4 months. Replace filters annually or as needed.
- Maintain Proper Water Chemistry: Balanced pH and alkalinity levels prevent scale buildup, which can damage heater elements and plumbing. See our How to Lower Pool pH guide for more information.
- Inspect Components Annually: During your annual drain and clean, visually inspect all accessible components, including sensors, heater terminals, and wiring, for signs of wear or corrosion.
- Keep Water Level Correct: Always make sure the water level is maintained above the skimmer to prevent air intake and pump strain.
Final Thoughts
A hot tub that bubbles but does not heat can be frustrating, but many of the common causes are easily fixable. Start by checking for simple flow restrictions like a dirty filter or low water level. Finally, consider the heater element or the control board as the source of the problem. Always prioritize safety by turning off power before inspecting or repairing any electrical components. Many parts are available for DIY replacement, but do not hesitate to call a professional if you are uncertain about any step.
Our Recommendation🏆 TOP PICK
XMK 6600-166 Temperature Sensor for Sundance Spas and Jacuzzi Hot Tubs, with Curled Finger Connectors and 6540-228 O-Ring
Check Price on Amazon- Compatibility: 6600-166 spa temperature sensor with curled finger connectors compatible with Sundance Spas.
- Temperature Sensor for Jacuzzi Hot Tub Models: All J300-J365 tubs use the 6600-066 curled finger sensor.
- Temperature Sensor for Sundance Spas Models: 2012+ 680 Peyton, 2011+ Select Series 2008+ 680 Denali.
- Temp Sensor for Sundance Spas Models: 1998-2004 Sweetwater Series and Portofino Series: Caprio, Metro and.
Hot Tub Sensor-Compatible with Balboa Spa Heater M7 System 30344 30042 30382, 24" Temp/Hi-Limit, 1/4" Dia Dual Purpose Sensor Hot
Check Price on Amazon- All spa parts hot tub temperature sensor, Replacement for Balboa spa M7 heater sensor 53605,32016,30042.
- KEYDINHT M7 temperature sensor for hot tub is a reliable tool for accurately measuring water temperature.
- KEYDINHT The bal'boa m7 sensor uses 12 feet of sensing wire, facilitating the movement and connection of.
- Cut off old bal'boa heat sensor 30344 Temp/Hi Limit Sensor in the hot tub and tape old wire to new spa.
