I agree with the others. You have a dangerous situation there. Being too hot is just as dangerous to them as being too cold, maybe even more so. What I suggest you immediately do has already been suggested, raise the lamp or move it so a lot less of the heat is going into the brooder. They need a chance to cool down.
I don’t care if you have 4 chicks or 40. To me, a perfect brooder is big enough and set up so one area is warm enough or even a little too warm. That way the chicks have somewhere to go if they need to warm up. But they also need an area that is too cool, maybe verging on cold. That way they can self-regulate and you don’t have to worry about what temperature it is in there at all. I’m guessing that is in your house so it’s not going to be all that cold anywhere in there.
I think the chicks are healthier and feather out faster if they get to play in varying temperature conditions. They are not as likely to get pasty butt or get bored. You’re less likely to have behavioral problems which seem to increase if they are too warm. They will regulate their food and water intake better so they are eating and drinking a healthy amount.
People tend to make this harder than it has to be by worrying about controlling things too tightly. Just give them some flexibility and you can relax. They’ll do the work for you.
I think you are to be congratulated. You noticed a problem and came on here to get help. Well done.
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