Has anyone installed Warmboard (or other radiant floors) as the only heat source in a building with 3 or more units? I’m curious to know how you decided to heat the common hallway and vestibules. Is it simpler to install a radiator in the vestibule and connect it to common electric? Or does it make more sense to extend the Warmboard zoning into the common hallway of each floor, since the common space is more or less equally distributed throughout the building? Is there a HPD or MDL rule that would eliminate the latter option?