Are you having trouble with your hot tub high limit switch? Is it tripping for no good reason or long before you think it should?
When your switch trips, your heater will turn off meaning you will soon be enjoying a soak in a cool bath instead of a nice warm hot tub. There are many possible causes of a tripped high limit switch. Today, we will examine the most common causes and what you need to do to repair them so you can get back to enjoying your nice warm soak without your heating turning off while you relax.
What Is a Hot Tub High Limit Switch?
Sometimes also called a hot tub high limit sensor or simply a high limit sensor, this is a safety feature built into all hot tubs that prevents them from overheating. It keeps the temperature from exceeding 120°F (49°C) in most cases. If it does reach these higher temps, the switch will trip, turning off your heater in the process.
Sometimes, problems with your hot tub can cause the switch to trip. When this happens, you may scratch your head wondering what is really going on.
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High Limit Switch Troubleshooting
Let’s check out some of the most common problems that could be causing the hot tub high limit switch to trip.
Air Problem
First, you should know that the problem could go away on its own. If there is still air trapped in your system after a refill, this could cause the hot tub high limit switch to trip prematurely. Monitor your hot tub if this problem begins after you drain and refill it. If it stops, chances are it was just air. However, if the problem persists, you must look at other possible causes.
Switch Reset
Sometimes, your switch just needs a good reset. On your spa pack you will find a red button that will reset the high limit switch. Once you reset it, test your hot tub to see if it trips again. If it doesn’t, the reset did the trick.
Switch Replacement
If the water in the thermal well is the same temperature as the water in your spa, then something has gone wrong with the hot tub high limit switch. You will need to shut down your spa, remove the old high limit switch and replace it with a new one.
Calcium Buildup
If the temperature inside the thermal well is higher than the water in the hot tub, then you could have calcium buildup affecting the flow of water. Low water flow can cause this higher temperature which will trip the hot tub high limit switch.
Clean your filter thoroughly, double check the plumbing for any blockages and make sure your gate valves are open all the way to ensure proper water flow.
Quickly remove metals like iron and copper from your hot tub water.
Thermostat Issues
Sometimes, it’s not the high limit switch at all, but the thermostat. It could be calibrated improperly or it may just be failing. First, make sure the thermostat probe is in the thermal well properly so it can take an accurate temperature reading. If so, then try recalibrating the thermostat and then testing your spa to see if that clears up the problem.
Double check the contactor to make sure it opens and closes properly when the thermostat is turned on and off. If it doesn’t, replace the contactor and then retest your system.
If all else fails and the hot tub high limit switch is still tripping, then it may be time to replace the thermostat.
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Learn MoreA Word of Warning
While troubleshooting a high limit switch is fairly easy to do, it does require that you have basic knowledge of your hot tub and its electrical systems. Remember, if you are uncomfortable working on your spa’s electrical systems, please call in a professional.
Closing Thoughts
Remember, don’t ignore a problem with your hot tub high limit switch for very long. The longer you let it go, the more you risk damaging other equipment on your hot tub. That means an even higher repair bill. In most cases, it is easy to determine what is causing the problem with your high limit switch.
Once you determine the problem, you can repair it and get back to enjoying those nice warm waters without your heater turning off just when you were getting comfortable.
Happy Soaking!
Need More Hot Tub Maintenance Help?
- Download our free Hot Tub Cheat Sheet. It’s a free, easy-to-use guide to help you keep your hot tub water balanced and sanitized.
- Subscribe to our Swim University YouTube Channel. We publish free video tutorials throughout the year.
- Check out our Hot Tub Care Course. You’ll get step-by-step videos and a step-by-step downloadable guide with everything you need to know about hot tub maintenance.
