Is a heated crawlspace one that is insulated and a unheated
one that is not.
Let me explain with a simple pic.
Click the pic below…
That diagram about sums it up.
I belive a heated crawl is preferable to unheated.
It depends on your climate if you have to heat the crawl space or not. If you insulate the perimeter of the foundation the heat loss through the floor to the crawl space may be enough to keep the pipes from freezing. The problem is that the floor will be very cold to walk on. To overcome this some people will heat the crawl space or insulate under the floor to make the floors feel warmer. With the floors insulated you have stopped any heat from radiating into the crawl space and again it will need to be heated to keep the pipes from freezing. With only the floor insulated then you will have a heat loss through the foundation walls.
Heated or unheated does not depend on the insulation but on a heat source either radiating through the floor or a separate heat source in the crawl space. In very cold climates enough heat may not radiate through the floor to keep the pipes from freezing.
Sums it up for me , thanks again