I am trying to install a Rinnai air handler coupled with a Rinnai demand water heater. I am running into a code issue in Maine. They are requiring a second heat exchanger because of perceived comingling of DHW and boiler water, even though this is not a boiler in the true sense.

I understnd that this is an issue in Mass. as well. does anyone have a simple work around that does not use a second heat exchanger? Has anyone ever dealt with this issue?

Thank you for all your help,