Originally Posted by goose55
My aqua hot has plenty of hot water but no heat at any of the zones. Anyone have an idea where to start on what the problem might be?
I had that problem. Ultimately, we determined that the "control thermostat" was bad (it was preventing the unit from heating up completely (158 deg - 190 deg). If the "control thermostat" is good - check the "low temperature cutoff switch" (basically another thermostat). The Low temp cutoff prevents boiler antifreeze from circulating if the temperature seen at the low temp cutoff is below 90 degrees (the unit does this to prioritize heating water over producing comfort heat).
A laser thermometer and a phone call to the Aquahot support folks will likely go a long way in terms of getting help on this. They were incredibly helpful when we were troubleshooting the problems that I experienced.