This 3 kW heater is widely used on several brands of hot tub, including Jacuzzi.
Two versions of this heater are available; with and without a pressure switch cable. The pressure switch cable (if present) is a second cable connected to the box of the heater, which is thinner than the main power cable. If your old heater has two cables, then choose a heater with a pressure switch cable; otherwise chose the version without one!
Just to add a bit more confusion, there is a different heater that carries the name H30-R1. The one on this page is 255 mm long (the metal part, excluding the plastic unions) and connects to 48 mm pipes. The other one, which is much rarer, is 330 mm long and connects to 60 mm pipes. Please check your heater dimensions before ordering!
Length: 255 mm (without unions)
Pipe unions: 48 mm inside diameter, for 1.5-inch pipe
Power rating : 3 kW
Nominal current : 13.6 A
1 year Tubs Parts warranty
LX Whirlpool : H30-R1