Hot Tub Temperature Sensor Testing – Full Guide

Hot_Tub_Temperature_Sensor_Testing_-_Full_Guide

Testing the conditions of your hot tub is an essential part of spa care. In addition to testing the heater, switches, and transformer, you should do the hot tub temperature sensor testing. The only thing you need is a multi-meter which can test Ohms.

You can get a multi-meter at any hardware or home store. It can help you check for shorts in cables, wires, and cords, as well as resistance. This can prevent potential damage and injury. In this article, we will talk about testing all the necessary components in your tub, including the hot tub temp sensor.

Hot Tub Temperature Sensor Testing Guide

  • Testing the Heater Step-by-Step 

  1. Firstly, shut off the spa bath at the spa pack and the breaker
  2. Then, remove the copper tabs or wires which are located at the heater terminals
  3. Set the multi-meter to the lowest Ohm setting possible
  4. Put the leads of the meter on the tip of each terminal
  5. Check the result. 10-14 Ohms is considered good for most heaters

If your heater shows ‘zero’ or ‘open’, it means that it has a crack. Also, it could mean that the coil inside is causing problems in the GFCI or circuit breaker. This means you should replace some heater element or change the whole heater. 

  • Testing Spa Transformers Step-by-Step 

  1. Shut off the tub both at the spa pack and the breaker
  2. Set the multi-meter to the lowest possible Ohm setting
  3. Find the resistance values on the transformer
  4. Place the leads of the meter onto both primary and secondary wire
  5. Compare the result on the meter to the specified specs on the transformer

Transformers work on 120V or 240V power and reduce it to a specific voltage which is needed for the component circuits. Transformers which are connected to the board by a solder can be a bit tricky to test with a multi-meter. Also, you should bear in mind that many hot tubs have several transformers of such kind. 

  • Testing Hot Tub Temp Sensor Step-by-Step 

  1. Shut off the hot tub at the spa pack and the breaker
  2. Adjust the multi-meter settings to 20K Ohm
  3. Find the end of the wires and unplug the board
  4. Put the leads of the meter onto the red and green wire
  5. Compare the result to the Temperature Chart and Thermistor Resistance Chart

For most hot tubs, the thermistors (high limits), hot tub temp sensors, and thermal cut-offs have a resistance of around 10 000 when reading at 77 degrees Fahrenheit. Warmer or average water produces lower readings. On the other hand, if the water is colder, the readings will be higher – around 50 000. 

To check your results, compare the readings to the Temperature vs Resistance chart provided by your tub manufacturer. If your meter shows ‘zero’, it means that the cable or sensor is likely bad. You should be aware that many tubs come with more than one temperature sensor, so you should do the hot tub temperature sensor testing on all of them. 

  • Testing Spa Fuses Step-by-Step 

  1. Shut off the power both at the spa pack and spa breaker
  2. Adjust the multimeter setting to 1K Ohm
  3. Remove the fuse from the fuse housing or the board
  4. Put the leads of the meter on each fuse end
  5. Compare the results from your readings and the printed levels on the fuses

If your tub fuses are blown, the readings will not show anything or will show ‘zero’. Keep in mind some meters can also show ‘open’ or ‘O.L.’ (Open Loop). In addition to meter-testing, you can also inspect a clear fuse to see if it is broken inside. Opaque fuses cannot be inspected in this way, but you can always use the multi-meter. 

  • Testing the Flow Switch and Pressure Switch Step-by-Step 

  1. Shut the power off both at the spa pack and the breaker
  2. Adjust the multi-meter settings to 1K Ohm
  3. Remove the wire from the switch
  4. Adjust the pressure switch if you get a reading other than ‘zero’

If you remove one wire, your flow or pressure switch should show ‘zero’ resistance because the switch is ‘open’. You can use a multi-meter to adjust the switch to ‘zero’. All you need to do is slightly turn the adjustment screw or knob until you see the desired reading. 

Understanding Meter Readings

Understanding_Meter_Readings

If your readings are showing resistance, it typically means good news, unless you are measuring the pressure switches. But, if your readings are showing no resistance, it means that electricity is taking another path. This generally means a defective cable or component. Since it is not known where the power is going, this situation can become a safety hazard.

You can also use the meter to test wire and cable length resistance. If you place a probe on each end, the meter should measure some resistance. On the other hand, if there is no resistance, it means that a short is causing a problem somewhere. 

Keep in mind you should always completely switch the tub off before doing any testing. Also, carefully read the instructions that come with the multi-meter to prevent any injuries. Lastly, call a professional if you are experiencing any issues with the testing. 

Globo Surf Overview

Testing the components of your hot tub is one of the most important parts of hot tub maintenance. This will prevent any possible injuries and damage and will show whether some components need replacement. Using a multi-meter, you should check the heater, the transformers, the temp sensor, the fuses, and the flow and pressure switch.

Keep in mind you should always turn off the tub before you attempt any testing. This is a crucial step that should not be skipped. Also, it is important to read the meter instructions before use. Lastly, compare the readings you get with the manufacturer’s regulations.

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My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!