I installed on of these.
https://www.amazon.ca/dp/B005UTVJMO/...FM12BPJS4J0ERR
Mainly because I put about 900 sqft of hardwood on our main floor.
It is a pretty easy DIY, depending on your experience. They even have a youtube video walking you through the installation.
The only "mod" I did was that for the water hookup, I installed a shutoff valve in an existing PEX line rather than use one of those crappy saddle valves.
Some complaints I have heard about these are the water usage. I just close the shutoff valve about halfway or more so that there is less wasted water.
It is a little unnerving cutting a massive hole in your main hot air furnace duct.