I have a Spa-Temp Series st-2115 system with Ramco controls approx 15 years old. The heater would not come up to 104 degrees. I followed the instruction on this web site to calibrate the thermostat. Now the low pump and heater will not turn on. Every other function of the systems works fine, even the low and high pump for continus flow. I can hear the thermostat "click" on and off but it seams it is not sending the signal to the motor and heater. All wires etc look ok, no corosion.

It is possible that when you adjusted the thermostat you have loosened one of the wires leading back to the PCB, check and make sure all the wires are making a good connection, if they are then there may be a problem with the PCB itself that just happened to appear around the time you were adjusting the thermostat. Also make sure your hi-limit is not tripped, on some of these older systems the hi-limit only stops the heater from functioning and as a result the thermostat would not activate the low speed either. does the timer (if it exists) acitvate the low speed? More than likely if everything else checks out it just be time for a new topside control panel with thermostat attached.