Diagnostics

Spa Repair Diagnostics-Heaters

 

 

Heaters

The most common style heater for spas is shown above; its a 'flow thru horizontal heater". Less common are low flow heater which can be a canister or a "U" shape heater.

All electrical heaters are mild heaters. They will heat 1-2 degrees per hour when operating on 115v and 5-6 degrees per hour when operating on 230v. Its a simple element that is resisting current flow and in doing so heats. As water passes by the element it absorbs the heat and goes into the hot tub. Typically you can NOT feel the heater and feel heat. If you do there is a flow problem. These heaters are design to transfer heat to the water efficiently and not overheat.

The most common indication of heater failure is tripping the GFCI. On spas operating on 230v the tripping usually is instant in turning on the power but can occur as the spa heats up. The other way heaters fail is they just stop heating. To test for both situations you need to have and can operate a voltmeter.

 

First, turn spa power OFF. Set your voltmeter to OHMS. With power to the spa OFF, place the probes on each post of the heater as shown below. This is one of the most common failure. The meter should read 10-15 ohms resistance. If not, you have a failed heater.

If you DO have 10-15 ohms resistance, change the meter to VOLTS +300vac. CAUTION: The following test must be done with the spa operating. If you are not experience in using a meter on operating equipment you should have a tech do this test. Turn on hot tub. When the heater light or icon is on solid, carefully place the probes back on the two heater post again. You should have either 115v or 230v present. If less and no error code on topside, your board has failed. Replace.

On hot tubs with either a canister or "U" shaped heater, the principles above remain true except you make the test on the heater cord or socket (on canisters) or on "U" heaters where the heater wire connects to the board.

 

 
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