How to Troubleshoot a Hot Tub Heater
Many clients have asked me this question. Why is my hot tub not getting hot? I have talked people through this process over the phone and have sent them a list of information on how to test the spa heater themselves. I do not normally recommend that an end user attempt to troubleshoot their own spa. Working with electricity can be dangerous, and working with electricity and water can be deadly. It is always recommended to contact a qualified service technician to troubleshoot any issues. That said, many people are more than capable of troubleshooting their own spa heater and this guide will help.
Hot Tub and Spa Heater Troubleshooting Guide
An easy to follow guide to spa and hot tub heater troubleshooting. Troubleshooting a spa heater can be a simple procedure if you have the right tools.
Note: This troubleshooting guide is intended for trained spa service professionals. It is not recommended that the spa owner troubleshoot their own spa.
The tools you will need to have are:
A multimeter, to check the voltage, and a clamp meter, to check the amp draw on the element. You cannot accurately troubleshoot a spa heater element without these tools.
Multimeter – Used to test the voltage at the terminals of the heating element.
Amp Meter – Used to check the amp draw of the heating element.
You will also need various hand tools. Screwdrivers, pliers, open-end wrenches, etc.
Note: The spa must be full of water and in normal operating condition to perform these tests.
To test the heating element, you must: Check the voltage at the heating element
1. Turn off the spa. (This means cutting the source voltage to the spa at the switch or disconnecting).
2. Open the equipment area and locate the heater assembly.
3. Open the spa heater assembly to expose the heater terminals.
4. Make sure all other wires and connections are clear of heater terminals.
5. Open the spa filter housing and remove the filter. Replace the filter cover and secure it to work.
6. Recheck the area around the heater terminals to ensure you can access the terminals with the multimeter probes, without the risk of touching other contacts.
7. Remember, when you turn the spa back on, it will be running on 240 volts of electricity. Water and electricity do not mix.
8. Make sure there is no water near the terminals where you will be working. Also, make sure you are not kneeling or standing in the water while testing the voltage at the heater terminals.
9. Reconnect power to the spa and turn up the thermostat to turn on the heater. Listen to the spa to see if operation sounds normal.
10. Turn on the multimeter and plug the probes into the meter as instructed in the meter instructions. You will be testing the voltage.
11. Carefully place a probe across one of the element terminals.
12. Carefully place the second probe on the other terminal of the heater.
13. Read your multimeter for the voltage across the element.
14. Remove both probes and note the voltage you read from your test.
15. Turn off the spa. If you received “0” volts at the heater terminal, your problem is most likely not the heater element. If you received the correct voltage at the heater terminals, you now need to check the amp draw on your heater.
Check amp draw on heater element
1. Turn off the spa. (This means cutting the source voltage to the spa at the switch or disconnecting).
2. Find the wires that connect to the spa heater terminals.
3. Attach a wire going to your heating element, with your ammeter.
4. Make sure all cables are secure and safe for operation.
5. Reconnect power to your spa and turn up the thermostat to turn on the heater.
6. Check the ammeter to see if your heating element draws amps.
7. Turn off the spa.
8. Write down the amp reading on your ammeter. If you received an amp reading from your heater. Your heating element is working. You need to look for problems elsewhere.
*If you received the proper voltage at the heater terminals, but did not receive an amp reading when the spa was running, the heater element is bad.
What to do if the heating element performs well during these tests, but does not heat the spa during normal operation. Remember step 5 in the voltage test. You removed the filter. Check the condition of the filter, run the spa for 24 hours without the filter in place to see if the spa heats normally. If the spa heats normally without the filter, replace it with a new one.
Now keep in mind that every hot tub/spa is different. If you have a digital system, make a note of any error codes that are displayed. The new digital systems in today’s spas will do a lot of the troubleshooting for you if you know what it’s telling you, but let’s save that for another article.