Need cold climate solution

[Theotilus]

I currently heat my home with a 3 ton Unichiller RC supplying hot water for my radiant floors. When the outside air reaches about 30 degrees F or lower the btu output is insufficient. I need around 36000 btus/hr. My research indicates that I need a DC Inverter heat pump with EVI technology to produce adequate heat.
Our outside air gets down to 15 degrees F at the coldest. A Daikin Altherma system is not within my financial means. I have found a unit built by Macon in China that would meet my needs but there is the usual issues of parts and service that come with that. I am an avid DIYer. I purchased the Unichiller used a few years ago and connected it to my radiant floor system which I installed myself. I have considered buying an inverter ductless heat pump and using a flat plate heat exchanger to convert it to air to water but don't think I have the knowledge to pull it off. Any solutions you can offer I would be open to.

Thank here in Bellingham, Wa.