I have a Caldera spa and the heater is not working. There are no error codes on the display. It shows 52 degrees and "temp" is on. I opened up the panel and took off the blue cover. The little red heater light is lit. I already cleaned the filter. The spa sounds the same when the circulation pump is running. There is enough water in the tub. I checked for burn marks near the relays and did not see any. I checked the voltage to the heater and got 120v on line #1 and the ground and 120v on line 2 and the ground. Does anyone have any suggestions?

Thanks, JT

Check between 1 and 2 to see if there is 220volts, if so then check for continuity on the heater. You should have 14 ohms or so between the black and white heater wires.

Thanks for the reply. I'm getting 16 ohms across leads 1 and 2. When I check for voltage thru the back of the connectors on #1 and #2 I don't get anything. If I pull off lead #1 and put one side of the meter thru the back of the connector on #2 and the other side of the meter onto the tab on the board where lead #1 was I get 220v. If I put lead #1 back on the tab I get nothing. Relay problem?

Heater is good then.

Turn off power, pull the heater wires off (#1 and #2) on your diagram. Turn power on and test the two terminals that the heater wires were previously connected to. you should have 220 volts there. If not then the heater relay board is bad. Once you take it out you will most likely see burn marks in the back of the board.

That was it. There was no voltage on the board and when I looked at the back there were scorch marks. Thanks for the help.