Heat Pump WH to dehumidify + existing indirect ??

Lee_8

I live in Sothern NH and have a dampness / midew issue in the full concrete basement of our 45 year old home.  It wasn't an issue until we replaced gas atmospheric boiler and traditional HW heater a few years ago.  Apparently  their, pilots and flue were providing adeqaute ventilation even in the summer. 

We run a dehumidifier and fans most of the year which is likely eating up much of the savings from the direct vent boiler.  Ventilation and air to air heat exchanger don't solve the problem since they would draw hot moist air in to cool space in the summer.  

At a recent home show someone suggested using a heat pump HW heater in the basement, it would dehumidify and use the heat it produces to heat water.  Can this be used with our 40 Gallon indirect in a code compliant manner?  Could we use it as a pre-heated source to the indirect?  If yes what is the advised preheat temp to address legionella in a 2 person household, 145 F?