Most dissatisfaction with the device is due to a lack of familarity by both warm air techs and homeowners with hot water heaters used as a heat source.
Unless the tank leaks, all of the system is usable.
http://discussions.tommmymac.us/wwwboard/messages/103717.html
http://www.heatpro.us energy businessmen’s knowledge
Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.