How to Troubleshoot a Hot Tub Heater

I have been asked this question by so many customers. Why won’t my hot tub heat up? 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 try 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 for any troubleshooting. That said, many people are more than capable of troubleshooting their own spa heater and this guide will assist them.

Spa & Hot Tub Heater Troubleshooting Guide

An easy to follow Spa & Hot Tub heater Troubleshooting Guide. Troubleshooting a spa heater can be a simple procedure if you have the right tools.

Note: This troubleshooting guide is meant for trained spa service professionals. It is not recommended for the spa owner to troubleshoot their own spa.

Tools you will need to have are:

A Multimeter, to check voltage, and a Clamp on Amp Meter, to check for amp draw at the element. You can not accurately troubleshoot a Spa heater element without these tools.

Multi-Meter: Used to test for voltage at the heater element terminals.

Amp Meter: Used to check for amp draw by the heater element.

You will also need various hand tools. Screw drivers, Pliers, open end wrenches, etc.

Note: Spa must be full of water and in normal operating condition to perform these tests

To test the heater element, you must: Check voltage at heater element

1. Turn Power off to spa. (This means to shut off source voltage to the spa at the breaker or disconnect).

2. Open 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 away from the heater terminals.

5. Open spa filter housing and remove filter. Replace filter lid and secure for operation.

6. Double check area around heater terminals to make sure you have access to the terminals with the multi-meter probes, without the hazard of touching other contacts.

7. Remember, when you re-apply power to spa, you will be working with 240 volts of electricity. Water and electricity do not mix.

8. Make sure no water is near the terminals where you will be working. Also, make sure you are not kneeling or standing in water while testing for voltage at the heater terminals.

9. Re-apply power to spa and turn thermostat up to cause heater to come on. Listen to spa to see if operation sounds normal.

10. Turn multi-meter on and plug probes into the meter as directed by the meter instructions. You will be testing voltage.

11. Carefully place one probe on one of the element terminals.

12. Carefully place the second probe on the other heater terminal.

13. Read your multi-meter for voltage at the element.

14. Remove both probes, and write down the voltage you read from your test.

15. Turn power off to 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 must now check for amp draw at your heater.

Check amp draw at heater element

1. Turn power off to spa. (This means to shut off source voltage to the spa at the breaker or disconnect).

2. Find wires that connect to the spa heater terminals.

3. Clamp one wire that goes to your heater element, with your amp-meter.

4. Make sure all wires are secure and safe for operation.

5. Re-apply power to your spa and turn thermostat up to cause heater to come on.

6. Check amp-meter to see if amps are being drawn by your heater element.

7. Turn Power off to spa.

8. Write down the amp reading from your amp-meter. If you received an amp reading from your heater. Your heater element is working. You need to look for problems elsewhere.

*I f you received the proper voltage at the heater terminals, but received no amp reading when the spa was operating, the heater element is bad.

What to do if heater element tests good during these tests, but does not heat spa, during normal operation. Remember step 5 in the voltage test. You removed the filter. Check condition of filter, run spa for 24 hrs without filter in place to see if spa heats normally. If spa heats normally with filter out, replace filter with new.

Now be aware every hot tub / spa is different. If you have a digital system, make note of any displayed error codes. The new digital systems on the spas today will do much of the troubleshooting for you if you know what it is telling you, but let’s leave that for another article though.

Source by J. A. Peters

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