It is possible you have burned out the electric element or overheated the control unit, but I'll bet the problem is you have not turned off the water heater bypass.
The unit has a bypass system that consists a set of valves that allow the unit to be filled with antifreeze for the winter without filling the entire water heater. There are usually Three valves and piping. The cold water line comes into a T. Out one side of the T is a cutoff with a pipe to the inlet of the heater. Out of the other side of the T is a cutoff connected to a second T. One port on this second T connects to a cutoff that goes to the hot water outlet of the heater. The other port of the second T is the hot water outlet and goes to the fixtures. To winterize, close both tank valves and open the cross valve. This connects the Hot and Cold water system and turnoff the tanks so it can be drained. For normal operation open both tank valves and close the center valve between the two T's. This allows cold water into the tank and connects the hot water lines to the fixtures, but blocks any water from going directly from the cold line into the hot pipes.
Whew - That took a lot of words for a simple device.
Ill bet you have the center valve open which allows cold water to flow into the hot water outlet. This would explain tepid water then cold only.
If this is not the problem, below there is a link to a troubleshooting manual that may help if you are handy with a meter and hand tools. The primary heat system is gas with 12 volt electric controls. Some models having a secondary 120 VAC booster system.
In normal operation it should work as you would expect. Turn on the faucet and get either 6 or 12 gallons of hot water (Gas, or gas electric both). Turn off the hot faucet and it should reheat the water and shut off.
Hope this helps
- Jerry
Here is the manual:
http://trekin.digital-digs.net/Share...ban%20V1.1.pdf
Linear Mode
