Try this: it's untested though:
tpt.el.watr.name="MGLQ"
tpt.el.watr.temp=255
function heat(i,x,y,surround_space,nt)
if tpt.get_property("temp",i)==256 then
tpt.set_property ("temp",0,i)
end
end
tpt.element_func(heat,tpt.el.watr.id,1,virus)


You needed to make an element function, not a function that is just run once per frame. Also the temperature of your element will probably almost never be exactly 256 degrees Kelvin.