Heat moves upward, so you could theoretically just heat the lower floor. In the summer, you would cool the upstairs and the downstairs would remain cooler. However, variables such as how extreme the heat and cold are in your house, and your house's quality of insulation, windows and roofing probably will affect your plans.
it depends of your house. if it has more than one floor then it might not. it also depends on how many rooms has radiant floor
Heat has a tendency to rise
Because heating systems use convection which causes heat to rise.
with a heater
Radiant floor heat is considered by many to be better than central heat because it is much better for our environment. Another reason is that is cost less to heat your house using radiant floor heat than central heating.
You dig hole in living room floor and wait for magma to come out. Then house is br00tally warm.
Because heat rises, and conversely, cold falls. Heat on the floor will rise and warm the whole house, not just the upper level. Air conditioning will fall and cool the whole house, not just the basement.
a two story house has a smaller surface area than the one story house for the given volume
This would normally be a smoke alarm/detector. At the basic lengths, you should have a heat detector in the kitchen, smoke alarm in the hallway of every floor. I.e. the entrance hallway on the ground floor and the landing on the first floor, second floor etc. If possible, also put one in the loft/atic and the basement (if you have one).
Garn WHS with radiant floor heating. simple, effective, economical.
Possibly, but the supply lines should be in the wall. Even on a slab house, the water should come into the house at the water heater and then be in the walls. Possible heat vent leak? I'm assuming a slab house because if there was access underneath, you would be able to tell if there was a leak.
no