Hot Tub Generic Heater Low Flo 6KW Heater Assembly 73790-Generic. Your existing 3/4" vinyl tubing will attach to this heater with no worries. This replacement heater doesn't have a plug on the end of the power cord like on the 1995-1996 spas. In most applications, the heater is connected directly inside the spas control box. If your existing heater plugs into the bottom of your control box, you may need the appropriate adapter. Adapters are listed next to your spa model on the chart below. Note: The 73791 can be used as an alternative to this heater in a spa that's wired 230 volts. Some service techs prefer the 4kW PDR to this 6 kW siting that it puts less strain on old/weakening 30 amp GFCI breakers.  73790 draws 25 amps (wired 230 volts) 73791 draws 16 amps (wired 230 volts)