Oh, that's awful! I'm so sorry your chicks died.
I haven't used the Sweeter Heaters since last year's hatches, but when I used them last year, they worked fine. I never tried to get a temperature reading under them, as several folks had commented that this is difficult to do accurately with a thermal panel. I went by the chicks' reactions.
It's really hard to know what went wrong without being there, but here are some questions to consider: How high was the lens of the heater panel above the litter? Was there an area in the brooder box that was not covered by the heat panel at all (a cooler area where chicks could go to eat, drink and mill around)? Did you turn on the heater several hours before putting the chicks outside to heat up the litter? Was the heater set up against a wall so that heat could be trapped under a portion of it?
I'll try to give as many details as I can
We have a 4x8 plywood brooder (2 feet high) that we put in our chicken coop. It was partitioned almost in half using chicken wire from our staggered hatches last year, so the 10 chicks had access to an area approximately 4x4. The heater was hung right in the middle, so it was not against a wall, so there was an area approximately 1.5 feet wide uncovered on either side of the heater. We covered the entire brooder with a chicken wire lid, so that the adult birds couldn't get at the chicks, and then covered most of the 4x4 chick area with a sheet of cardboard so they didn't get pooped on by the guineas in the rafters. The heater was between 3 or 4 inches off the bottom of the brooder floor. We had just laid paper towel on the floor since in past years we've had issues with chicks eating pine shavings and getting pasty butt in the first couple of days. We turned the heater on Thursday morning so we could monitor it all day (and make sure it didn't like, start a fire!) and so it was on about 24 hours before we put the chicks in it. We set their food and water pretty close to the heater so they wouldn't have to go far to get a drink.
When my husband first set up the heater Thursday, he put the meat thermometer underneath and it read ~50 degrees after a couple hours. I explained to him that we wouldn't be able to get a good reading given the way these heaters work and that we should just trust that they'd work. I went out and touched the lens to make sure it was heating, and I could only hold my hand there for a second or two before it felt too hot; so I knew it was working. It was because of my husband's concern that we lowered the heater from 6 inches above the floor recommended to the 3 or 4 inches.
Friday morning around 10, we took a large towel out of the dryer, put it in a cardboard box, grabbed the 10 chicks from the incubator and brought them to the brooder in the coop. We dipped their beaks in the water as we put them into the brooder. They clustered together under the heater and looked like they were ready to take a nap. I thought nothing of it. I checked on them just about every hour throughout Friday, since I was going to the coop to collect eggs for hatching anyway. Daytime temps were in the mid to high 20s. The chicks were always under the heater, not shivering, not panting, and at times some were further away from the group and sometimes they were all grouped together. The last check was around 7pm when my sisters came over for a game night. Nighttime temps dropped into the teens.
In the morning, my husband went out to check on them around 8am, and 8 were dead and the other two did not look good. The dead chicks were all over the 4x4 section of the brooder they had - some under the heater, some in the far corners, and some in between. Within a couple hours, the remaining two were dead as well.
Today, we put a concrete paver and a section of 2x4 under the heater, and after a few hours we used our infrared baby thermometer to take the temp of them. The surface of the heater read 160, but the paver and the 2x4 were only around 60. The floor a few inches away from the heater was 37. We lowered the heater even further, and a few hours later my husband took readings again and the paver/2x4 read 80 degrees.
We did have one late hatch chick. When we pulled the 10 out of the incubator Friday morning, I saw that one chick had died midhatch, but I didn't notice this other one until I grabbed the egg to remove it - it had pipped, and the chick started moving it's beak. So we left that chick in the incubator with some wet paper towels to increase humidity; a few hours later it had made a sizable hole. Saturday morning, that hole hadn't gotten any bigger so in a desperate attempt after knowing all the others died, I helped it out of its shell. Part of the membrane had dried onto its back and I couldn't remove the shell there so I left it. Today I used a warm, wet paper towel to remove as much of the shell and membrane as I could, and as of tonight its doing surprisingly well! However, its one leg is curled up quite a bit still, and under normal circumstances we might have culled it, but now.... we just might end up with a house chicken named Lucky!
I'm devastated and trying to figure out what happened since we have 42 more eggs in an incubator set to hatch in two weeks.
