Heat pump for water heater

[UNCSoc]

Ecorenovators,

It seems that there are downsides of the heat pump water heater as well as the tankless water heaters. But why not combine them?

So the first source of hot water would be a standard heat pump water heater in my basement utility room. I would need one that would only use the heat pump--no other source of heat (would have to shut off any backup heat in this unit).

From there the heated water would run through an inexpensive (propane) tankless hot water heater. If the water was not hot enough, the tankless hot water heater would come on as needed, and the fully heated water would be ready for use in the house.

In the summer, we would set the heat pump water heater at a higher temperature to remove the heat and humidity in the basement. In the winter, we might set the temperature on this unit lower. And maybe we could move some air through a door to a large insulated (ICF block) crawl space, which under some conditions may offer another source of "geothermal" heat. And that way the utility room wouldn't get overly cold from the heat pump (cold) air and "leak" that cold into the rest of the basement. Could insulate the walls of the utility room to keep that relative cold enclosed. Or just use mostly the tankless hot water heater in the cold winter month or two, and keep the heat pump hot water heater on a very low temperature.

Does any of this make any sense? I am not that familiar with these systems so would be thankful for any advice. Thanks.