Therm [Cal Spas] 16.25" 4.0kW Flo-Thru Incoloy Heater (26-0165-5S-K) poolcovers and this Darlly 4CH-15 cartridge

and this Darlly 4CH-15 cartridge is designed for compatible spa and pool applications where the original cartridge has become loaded

A circuit board is useful because it manages core system functions

This replacement is especially useful during service work when damaged covering needs to be renewed or when a connection needs extra sealing support

or added strain on the cleaner’s drive components

3 inch hole size

Therm [Cal Spas] 16.25" 4.0kW Flo-Thru Incoloy Heater (26-0165-5S-K) poolcovers and this Darlly 4CH-15 cartridgeTherm [Cal Spas] 16. 25" 4. 0kW Flo Thru Incoloy Heater (26 0165 5S K) provides a targeted heating solution for Cal Spas, combining the specified output and construction needed to restore consistent water heating without relying on a generic substitute. Its 4. 0kW heating output and 16. 25" heater length should be matched to the original equipment requirements before installation, since spa heaters are not universally interchangeable. A heater