Is your bestway Lay-Z-Spa 2020 Flip Up Display AirJet pump not heating up? Possibly tripping the RCD shortly after the 'Heat' button is pressed? Then it is very likely that your PTC heater assembly has failed and will need to be replaced. Please be aware that this device is designed to operate at 110-120 Volts. The operational voltage of your system will be stated on the silver data panel affixed to the case