My house has a crawl space. The walls are insulated; there is a vapor barrier on the dirt floor as well as the concrete foundation walls. We are on a well and the pressure tank is located in the crawl space along with plumbing supply and drains.
We have wood and ceramic floors, which do get cool - especially in the winter. The temperature in the crawl space during the winter months can go as low as 34 to 36 degrees. I would like to insulate the floor, but my concern is that if I insulate it I will lose the heat that does radiate from the living area to the crawl space, and then my plumbing might freeze.
My heat source for the house is a gas fired Monitor heater. The home is located in Alaska so winter is long and the temperatures in our area can go as low as -35 degrees for 2 to 3 weeks or more at a time.