Re: Hydronic Flooring
You have returned nearby. Any way to get a couple supplies routed through the garage and up through the floor? Your existing heating plant is likely oversized like most anyway, so the extra load wouldn't hurt. Getting through the concrete floor won't be easy, but it's doable with a good hammerdrill. You might even be able to get away with one large duct, maybe a 6x14" on a 10" branch.
Ideally, you'd do a load calculating and determine what percentage of the heat that room requires compared to the rest of the house and proportionally distribute the air accordingly.
Another option could be adding a small direct vent fireplace or stove if you have gas heat. It would also supply heat and light during a power outage.
1925 Two-Story Stucco Beaux Arts Neoclassical