Reply by Jim Finn

I am a retired heating contractor (Wisconsin) In floor heat is slow to react and expensive to install. Forced air gas its the way I would go. Even a space heater with a fan would work well. Unless you sleep in your shop it will be expensive to operate an in floor system. Turn it on when you walk in or with a timer and it has to heat up all that concrete before it starts to heat the air in the room.

-- In God We Trust