ew, Fairbanks gets way cold.
with those temps, still follow my general water guidelines above... but by -30 you might want to start heating.
Swedes luckily are pretty pudgy ducks, good solid, and stay warm well.
But -40 and below is horrid cold.
I have heard that some people up there vent their garage heat to the coop or attach the coop to the house, or attach the coop to the heated water tank building. The point of course, get some heat from somewhere!
Never use a heat lamp for heat... heat. I know people just north of Anchorage use flat panel heaters rated for outside in their coops.... but fairbanks might be too cold for those.
Personally I would set up a sleeping area in the coop for the ducks, line it with the in floor heat mat that is made to go in bathrooms under tile. I think that stuff is safe for wood too. So I would make a wood box where the bedding and ducks sleep, heat mat under box.
Maybe set it on a timer to go on at 9pm and off at 8am. Dunno, the electric still might kill ya.