I'm having no luck finding reputable hydronic radiant experts near Leesburg, Virginia who will call me back. I had a large sunroom addition (approx. 867 sf.) added to my home. It is a concrete slab on grade. I had pex tubing embedded in the slab so I could later add a hydronic radiant floor heating system. There are five (5) French door openings into this room from the main house. I also have a couple of mini-split systems installed in the room. I can maintain a comfortable air temperature but the slab (porcelain tile on slab) can get uncomfortably chilly on stocking or bare feet. I'm now looking for solutions to heat this floor and possibly combine to replace an aging (20 year old) electric domestic hot water heater. I have propane available and that is likely my preferred route, unless someone can propose something more efficient that will get the job done. I've called heating contractors. I've called plumbers. I've requested referrals from manufacturers (Buderus, Polaris) and they have actually provided referrals but either no one calls back or those that do don't really seem to have any experience or interest. I'd really appreciate any assistance. Thanks.