Hot tub heaters can fail for many reasons, here are the Top 5 causes spa technicians encounter:
Spa and hot tub water flow issues
1- Spa Water Flow Error
If the control system is registering inadequate or no flow, the heater will automatically be turned off by the system.
2 - Pressure or Flow Switch detects spa water flow
A low flow error is sensed differently by every system, some systems use a pressure or flow switch to break or complete the circuit. If the water flow through the system is below the required amount, or the flow switch can’t make contact, a flow error will occur.
All Flow SwitchesAll pressure switches3 - Sensor to detect spa water flow
Other types of systems rely on sensors to detect flow. If the water is moving too slowly the info sent back to the control system from the sensors will be outside of preset limits and trigger an error.
All control systems4 - Dirty or damaged spa filter cartridge
A clogged or damaged cartridge will slow the movement of water through the cartridge and the overall flow of the system. When this happens, the water will get too hot inside the heater and trigger a high limit error or flow error.
Filter cartridges5 - Damaged or clogged spa circulation pump
If the circulation pump is damaged, or the impeller is clogged, this will either slow the water flow or stop it completely. This will cause the safety items mentioned above to trigger a flow or overheat code. This can be caused by a bad motor, non-primed pump, or internal damage to impeller or wet end
Debris stuck inside the spa and hot tub heater tube
Debris inside the heater will cause damage to the element. When debris passes by the filter for whatever reason, it can get hung up on the element and cause a failure.
This can rot out the element until it fails and trips the breaker
Overheat and trigger a high limit code.
If enough debris is clung to the element, it can even restrict flow enough to trigger a flow error.
Damaged spa and hot tub control system
1 - Damaged spa control system circuit board
Damage to the control system or circuit board can cause the heater not to work for many reasons.
2 - Damaged spa and hot tub heater relay
A heater relay is a part of a circuit board that when engaged, allows power to flow from the circuit to the heating element. If the relay is damaged or otherwise unable to close and allow power to pass through it, the heater will not engage.
3 - Spa and hot tub water-damaged flow sensors
A damaged sensor that is sending improper resistance values (bad information) back to the circuit board, will cause an error. If the circuit board itself is damaged and unable to read or properly interpret the data, it will also prevent the heater from working.
4 - Spa and hot tub damaged pressure or flow switch
If a pressure or flow switch becomes damaged the heater will never engage. It is also possible that the pressure or flow switch is working properly, but damage to the circuit board or software is preventing it from recognizing that proper flow has been established.
Improper spa and hot tub water chemical maintenance
1 - Low PH or alkalinity of spa and hot tub water
When PH or Alkalinity gets too low the water becomes Acidic. The heating element is always exposed directly to the water, and during both on and off times, it is sitting fully submerged. If the water becomes acidic, the heater element will become corroded and form tiny holes. These holes will allow electricity to escape the element and become in contact with the water causing a direct electrical short and tripping the main circuit breaker or GFCI. If the circuit breaker or GFCI has also failed, it can cause a seriously dangerous situation as all the water in the tub and plumbing will be holding a current of electricity.
2 - High PH or alkalinity of spa and hot tub water
High Alkalinity or PH causes problems with the sanitation of the hot tub. One of those problems is how it affects other chemicals in the water. For example, Calcium is very much affected by alkalinity levels. When Alkalinity or PH become very high, it can cause calcium to come out of solution and adhere to surfaces. White hazy areas above the water line inside the tub, deposits around jets and suctions, as well as deposits accumulating on the heating element. When this happens, it can damage the element and cause a failure.
3 - Excessive enzymes, flocculants, scents, clarifiers in the water of a spa or hot tub
When misused or in excess, these chemicals can cause issues with the heater. Excessive enzyme use can cause a residue inside the heater and affect sensors. Flocculants can cause particulates to combine, and when this happens inside a heater during off times, it can cause a buildup that can damage the element or sensors. Scents and colored dyes can also leave deposits when used in excess. Using Clarifiers to help with water clarity can also cause a decrease in flow. As clarifiers form a membrane over the pleats of a cartridge, too much usage can cause a reduction in flow and trigger errors in the system.
Extended non-use of your spa or hot tub
1 - Spa sits unused for long period of time
Whenever a Spa or Hot tub is going to be sitting unused, it is important to be sure to drain and blow out all the plumbing lines, equipment, and the heater.
2 - Idle spa and hot tub heater heating element
If a failure needs repair or during a planned prolonged non-operation, it is crucial not to leave the spa and its plumbing full of water and let it sit. The quality of the water inside pumps and heaters will deteriorate rapidly, and the same issues found with chemical damage will occur. The element will rot out and corrode in the water. When you attempt to use the spa later, the element or the complete heater assembly will need to be replaced.
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