I have a '95 Khyber hot tub with an original heater that stopped heating. I replaced the heater with a 73790 Watkins No-Fault PDR heater (recommended by Hot Springs manufacturer). After turning back on the power to the tub, the new heater is not heating either.

The circulation pump, jets, and light are all working but the heat is not. I turned off the power at the breaker for 30 seconds and then turned power back on but still no heat. There is no reset button on this PDR heater.

Please help.

Have you checked voltage at the 30 amp breaker? Your spa, if wired per/instructions, has two breakers. One breaker (20 amp220v) powers the pumps and light, the other (30 amp 220v) powers the heater only. If it malfunctions, there is no sign, other than a lack of heat.

Common problems would be:
thermistor bad
breaker bad
flow/switch bad
bad flow switch relay or heater relay (both are 12v dc coil T-92 relays)
possible burnt wires.


When measuring for voltage across the breaker, be sure to meter both poles at the same time to test for 220v. Don't test them one at a time.

Good luck!

~Swine