I also bought a 250W infared bulb yesterday from the local feed store for three 2 week old chicks that I set up in a large dog crate, and it definitely seems like overkill, even set up outside the door and pointed inside, its 85 degrees inside the crate.
Consider getting an in-line dimmer (rated for at least 300W) for use with the 250W lamp. The 250W lamps were the only ones available locally when we brought the first batch of fuzzbutts home, and it was definitely overkill in the small brooder tub. I scavenged a dimmer pack from a torchiere lamp that was headed to the trash, and repurposed it for the heat lamp. We have been walking the lamp down every Saturday for the Black Australorps - we are at 75F currently. The Red Sex Links are getting the full 250W, and we tuned the temperature based on their behavior. I don't know what the specific temperature is right now, but the balance of spacing with snugglage seems about right.
During the transition to the wall-to-wall brooder, they were in the green tub without the heat lamp for about 30 minutes. They were in an extreme puppy-pile wedged into the corner desperately trying to retain heat. It was pretty obvious they were cold.
