Now that my EKO 40 is up and running and heating my basement and main living area I want to explore my options for heating my second story. My house is really a 1 1/2 story house built in 2002. It has the typical knee walls and small attic spaces on each side upstairs. The upstairs area I want to heat with my EKO has a small seperate furnace in a closet that I could use for a WAHX but I also have the ability to install baseboard or some of the more modern heat panels. I have access to the kneewall attics and I am able to get my pipes from my storage tank in my basement up into the kneewall attics. Problem is that area is not part of the thermal envelope and would likely freeze when the temps get really cold outside. The staircase leading upstairs is open so it doesn't get that cold up there. If I keep downstairs at 70 it is probably 63-65 upstairs in the two bedrooms that I want to heat as long as the doors stay open. For some reason the builder insulated the floor joints between the main floor and upstairs half story. When I installed my storage tank in the basement I left one inch copper tapings valved off for this very purpose. Is running a Water/water exhanger with antifreeze in the upstairs circuit the best way?