I know there has been many posts about heating the coop with a heat lamp, I've done the search. I don't think I need to do a full 250 watt heat lamp, I was thinking more on the lines of a 75 watt flood lamp since the coop is fairly small and air tight. On cold nights, like last night, the water bowl is frozen solid. I was thinking of starting with the 75, and could always go up if need be. We use a 40 watt bulb on a timer now (comes on just before dusk and stays on for about 3 hours) to give enough "daylight" for eggs, and it works fine, we get eggs every day. My worry is, if I use a light all night now for heat, will it mess with the egg production?