There is nothing more disappointing than preparing to take a good soak only to realize that your hot tub is not heating the water. When your jets are turned on and the water is still cold, your heater is running but not heating up or you have some flashing error codes, we are here to help.
The following are the 7 key causes and remedies in a step-by-step breakdown when your hot tub is not heating. Be it a conventional spa, or maybe a Coleman or like one of the plug and play inflatable types, we too will have you troubleshooting quickly and safely.
1. Low Water Level/ Air in the System
The level of water in the hot tub should never drop below the skimmer and jet intakes. When it falls too low, air may enter the plumbing system and form an airlock that will not allow the heater to switch on.
Fix:
- Turn off the electricity.
- Fill the hot tub to the desirable level.
- Unscrew the pump union slightly, and allow a little water or air to come out. This is occasionally referred to as burping process
- Re-fire the hot tub.
- Typical Symptoms: Heater not lighting, jets will be functional.
2. Blocked Water Flow by Dirty or Clogged Filters
One of the causes that are generally ignored in case of heating problems is poor water circulation resulting in clogged filters. It will not work when the heater detects low flow to prevent heating the heater.
Fix:
- Remove the filters and clean them well with a hose.
- Clean the filters with a cartridge cleaner once every month.
- Change the filters after one year or when you realize that they require it.
- Typical Symptoms: FLO, heat running but no heat, pulsing jets, weakly.
3. Heating Mode Set Wrong: Rest / Economy vs Ready Mode
Most of the hot tubs contain some heating modes. Only when the filtration cycle is scheduled, the Economy, or Rest mode will heat; the Ready mode will maintain the desired temperature at all times.
Fix:
- Look in your spa control panel.
- Shifting out of Economy (EC) mode or Rest (SL) mode into Ready or Standard (ST) mode.
- Consult your manual to find out specifics of your brand.
4. Bad Heating Element or Heater Circuit :
The heating element is actually in the very center of your hot tub. All failures identified occur as a result of failure through corrosion, and scale build up, the most common.
Fix:
- Turn off the electricity.
- Remove the panel, and test those heater terminals with a multimeter.
- A reading of 10 to 14 ohms normally indicates that the element is working well.
- In case the reading is out of that range, then you are supposed to go ahead and replace the element.
- Most frequent Symptoms: No rise of temperature even with heater running.
5. Airlocks or Circulation Problems in the Plumbing
Although filters are clean and the water levels are sufficient, issues and circulation will result in improper water flow and halt the heater kicking on.
Fix:
- Look at the pump and see that it is in proper working order.
- Check jets and plumbing to see that they are clear.
- This can be done by loosening the union at the pump to free lodged air.
6. Bad Sensors, Pressure Switch or Flow Switch
The pressure and flow switches check that the water is flowing properly before permitting the heater to turn on. One or both of these could be faulty or malinterpreted and turn the heater off before it should.
Fix:
- Check the sensor connections to see whether it is corroded.
- Clean or change the pressure switch.
- Look at twisted hoses or valve obstacles.
7. Error Codes and Brand Specific Problems
A large number of the plug-and-play and inflatable hot tubs such as Coleman and other models have digital displays with error codes. Among the most widespread ones is the E02 code in Coleman spas, which is normally an indicator of a water flow or heating problem.
Fix:
- Wash filters.
- Test the water level.
- Hit the reset button of the heater.
- Make sure that the GFCI outlet is not tripped.
Note: We do not include brand names in the meta title here but they are used organically in the content to be relevant to the search engines.
Bonus: The Way To Know Whether Your Hot Tub Heater Is On Or Not
Doubt whether the heater is functioning or not? Apply these speed tests:
- Touch the heater housing-that should be warm after 10 to 15 minutes of use.
- Check voltage between terminals w/ multimeter.
- Listen to a low hum of the heating element.
- When you do not observe such symptoms, then chances are high that your heater is not functioning.
Preventive Maintenance Suggestions
In order to minimize the possibility of heating problems in the future:
- Clean filters once every week
- Always keep water level up
- Regulate PH and alkalinity
- Apply an insulated cover that is weatherproof
- When your spa has been used a lot, shock it
- Such minor steps will help avoid expensive repairs and downtime.
Comparison Table: Troubleshooting At a Glance
| Problem | Symptom | Likely Cause | Quick Fix |
| No heaters functioning | Cold, light heater on | Fired out component | Change the heater element |
| Heater on and no heat | No temp rise, jets good | Clogged filter, no flow | Clean/change filter |
| Water will not heat, no mistake | No codes, cool water | Airlock, low water level | Refill and bleed system |
| Plane heaters not functional, jets OK | Blow jets, cold water | Mode is set to Economy | Change to Ready/Standard mode |
| E02 / FLO error | No heat, warning on display | Clogged filter, flow sensor issue | Reset the system, clean the filter |
Hot Tub Heating Problems FAQs
Why will my hot tub not heat up?
Most typically, it is caused by a clogged filter or improper settings, or an airlock.
What is E02 in a hot tub?
Normally, E02 is a problem with water flow. Having clean filters and checking the pump.
Will I be able to repair heating problems in an inflatable hot tub myself?
Yes, a lot of typical problems such as airlocks or clogged filters can be fixed by a DIY person.
What is the time it takes a hot tub to heat?
A: 4 to 8 hours average, depending on size, starting water temperature and insulation.
Why is the heater on and water cold?
You may have scale build up on your heating element or a bad pressure switch.
Final Thoughts
When your hot tub fails to heat, most likely, one of the following common issues are involved: an incorrect water level, unclean filters, improper settings, or a bad heater element. Fortunately, some of them can be corrected without consulting a specialist.
Spend some time wading through each of the 7 solutions above. When you have done just about all you can do and the problems remain, you might have to check the wiring or swap out internal parts. Do not hesitate to ask a certified spa technician when you are not sure.
