Tiger River, Caspian, not heating

[Dline]

Tiger River Caspian, CHP3L 3086

My 2009 Caspian 4K heater quit. Found a dark or burn spot on the power input circuit board near a relay. All the pumps run, just no heat. Don't seam to have a short, the circuit breakers stay on. I cleaned the ground on the no fault heater case, unsure if this caused problems. No power to the black wire leading to the no fault heater. Assume the burn on circuit board is the problem. The red wire to heater has 120 volts. Test resistance between the two heater wires, shows 18 ohms. No ohms from ground to each heater wires.   Two led lights on the main circuit board are on. LIM is green and HTR ON is red. The CONTROL UNPLUGGRD only lights when unplugged.

Further testing, disconnected all wires to heater. Connected a separate power source, 120 volts to each heater wire and a ground. Made sure the transfer pump was running and moving water. The No fault heater did not get warm. 

Question: (1)  Have I tested the heater properly? (2) Will this heater cause a new circuit board burn out? There are 3 sensors in the heater, are they normally open or closed? I want to check each sensor.

I will replace the power input circuit board. Wonder if I need to replace the heater.

Thanks for your help. Doug

[cranbiz]

18 ohms should be good to go. Look in the heater tube and make sure the element isn't touching the side wall.

Do you have continuity from the relay contact point to the heater terminal? If so, the burn mark is OK, if not you can either repair it or buy a new relay board. The relay is probably bad so again you either need to repair the board by replacing the relay or buy a new relay board.

Most likely the heater relay stuck on and caused the damage. It's not an uncommon failure.