WF Envision 049, "DHW" switch off Our WaterFurnace’ Envison 049 is only three and a half years old. It’s under service contract that serviceman comes to check every spring to make sure the unit running properly. Early last month the unit called for service. The repairman came to check and conclude the compressor went dead. It was extremely rare occurrence according to the repairman. He said WF people told him this was the third incident in this particular model. Four days later (Nov. 10) he brought a new compressor to replace it. This past Sunday it called for service again. I checked the indicating lights on the unit first before called for service. I noticed the “Status” light blinking (which meant normal according to the manual), and “DHW” light on which meant hot water discharge was shut off. The switch to turn on and off of this discharge is right under the “DHW” light. I checked the manual to learn the discharge needs to be turn off while the unit is in service. Clearly, the repairman came to replace the compressor forgot turning it back on three weeks ago. Another serviceman came just before noon and spent almost three hours trying to find out the problem. He did make the unit run but could not figure out what went wrong. According to the manual, when “DHW” is on and water temperature reaches 130oF “… unit’s hot water pump will be de-energized to prevent excessive temperatures.” My assumption is while the “DHW” was left off and the water temperature reaches the limit the de-energized system could not kick on and stop the unit. Is my assumption correct? Had this overheat (assumed) partially damaged the unit?