My hot tub doesn't get hot, or not hot enough

You turned your spa on yesterday, but the water is still only lukewarm, or even cold? You might have a heater problem, but other - often simpler - reasons can also be the source of the problem. We'll explain, step by step, how to identify the cause of these malfunctions.

We strongly recommend that you call a qualified electrician or technician to carry out electrical operations. If in doubt, contact us.

First of all, check your control panel

Is there an error message?

If the answer is yes, refer to the manufacturer's user manual, or our page (this page for Gecko control panels) listing the main error messages that can be found on a control panel, and follow the instructions.

If the answer is no, there is a good chance that the problem comes from the heater.

The water doesn't get hot

So, your heater isn't heating, but there's no error message. It could be that the resistance in the heater has failed, which means you need to replace the resistance.

If you need a visual, picture a filament light bulb. The filament, much like the one in the resistance, connects the circuit and lets the electricity flow, lighting up the bulb. If the filament breaks, the light stops shining. The same goes for the resistance in the heater: if it breaks, the heater stops working and your spa gets cold.

There are many reasons why a resistance can break, but usually it is due to voltage variations in your spa’s wiring. Your spa needs a constant voltage around 230 V. This variation may be an overvoltage, like during storms for example, or an undervoltage, if the distance between your spa and your electrical panel is too long, and the cable too thin.

You need a multimeter to determine the value of your resistance, in the unit ohm (symbol: Ω).

Always turn off the power to the spa before performing this operation!

If the multimeter indicates a value between the two terminals, your resistance has no problem (the value will depend on the power, in kW, of the heater). If the multimeter indicates OL, — or 0, you must change the resistance (see the video opposite for replacing a resistance)

The water is heating, but too slowly

Your spa is heating up, but the heat is too low and your water remains lukewarm? The problem is not your heater: it either works or it doesn’t, there is no in-between.

On average, a spa gains between 1 and 3°C per hour, depending on its size, insulation, weather conditions, etc. It will not help to put your hand in front of the heater outlet (or on the heater!) to see if it is heating: the water at the heater outlet may be slightly warmer than the water in the rest of the spa, but the difference is so small that you may not even notice it.

The easiest way to check whether the heater is heating or not, in addition to determining the value of your resistance with a multimeter, is to measure the voltage, in volts, with the same device.

Turn on the power supply to your spa to perform this operation!

If the voltage is around 230 V between the two terminals, and there is continuity (see previous section) your heater is necessarily heating correctly.

Two probable causes then explain the low warming.

• Your control system only supplies the heater intermittently. An error message will appear (sometimes intermittently, so check it regularly) on your control panel.
• Your spa is poorly insulated, and is losing its heat. It is essential to use a good cover in this case.