So if I used the bigger heat bulb like 250 watt you are saying it uses less voltage or current?
I took a course in "farm electrification" 40 years ago but it was too much like math which I hate!!!
Why do you need so much wattage? What is the situation of the well/ tank enclosure/ wellhouse? And how cold are we talking? My Mom/ Dad used to have a little insulated wellhouse, it rarely was in danger of freezing. "when it was" I took a pair of fairly large incandescent lamps (I forget, maybe 200W) and wired them in SERIES, that is, two 120V lamps across 120V. That made the lamps draw 1/4 of the wattage, so effective only about 40w or so. They being on at all times, provided a bit of heat, and because they were in series they would last forever.
I just meant the above as an example, the question remains, why you need so much? Also are you putting them on a thermostat?
