Infra red is nice. Even with air conditioning, it just doesn't take much to raise 75 ambient air to the 90 the chicks like for week one. They won't want it that warm for long. In fact, the purpose of the lamp is not necessarily to create a 90 degree world for them. This goes against nature. A broody mother hen only provide a warm spot of her body, if and when and as they need it. The rest of the time, chicks are busy little bodies running, jumping and pecking around in 50 and 60 degree air. The purpose of the lamp is to merely mimic the hen's body.
A warm circle big enough for your seven chicks to come into when, if and as they need it. That's all. Too hot is almost always more dangerous than a bit too cool. If they are cool, they'll peep and tell you. Lowering and raising the lamp adjusts the heat they sense. Remember, their bodies are 2" closer to the lamp than the floor of the brooder. Always have cooler areas of the brooder for them to go and self regulate.
Enjoy the journey.