I don't use a heat lamp, never have. First (and foremost,) the safety issue, for the chicks and my property. Second, common sense would tell you it is totally unnatural to be exposed to bright light 24/7. (I am a firm believer that is also a serious mistake made by hospital nurseries for human babies as well) All you have to do is watch chicks under a heat lamp to see how hyper and stressed they are. I currently use a Brinsea heater brooder. (inserting a commercial here) this is the one I WON 2 YEARS AGO FROM BACKYARD POULTRY MAGAZINE!!! In their 21 days of Christmas giveaway. I am also in the process of purchasing a Sweeter Heater for the coop.
I do have a brooder "area" already that breaks down for storage that is designed to fit under the roost area in my coop that even has it's own pophole that opens out into an area of the run that can be temporarily separated by fencing. The problem I ran into was my 2 survivors had to be brooded in the house because they initially needed to be hand fed, etc. or they would not have survived and I still cannot move them to the coop as the crazy weather (supposed to snow tonight) would be too radical an adjustment. I am hoping to move them to the coop brooder next week (they will be 2 weeks old on Sunday) if the weather levels out. I have never had success integrating chicks as young as you suggest with the adults (I've tried) and because of the timing, I doubt mixing them in with the new chicks will work either. The other problem I have is I do not have the floor space in my coop that would be needed to handle that many chicks in the coop with all the "extras" needed to support that many. However, as I type this I realize I might be able to "stage" the older chicks out into the coop before the new ones arrive, then move them out as soon as I get the first ones integrated, etc. It will take some adjusting since I have neither the room nor the beautiful setup that you have (my little coop is elevated, combined with a greenhouse in a "creative" way, etc.) but it is worth a try! I can always still re-home later if it just doesn't work.
Edited by chickisoup - 5/13/16 at 8:38am