Eggs installed at home

I’m slightly worried about the temperature regime in my enclosure. When I was setting up the box, I noticed my max-min thermometer is no good. The mercury has separated. I’ll try and buy a replacement one tomorrow. So I've put a couple of other standard thermometers in the box. One is on the base, the other is in the space above the eggs. The air temp has been around 20 degrees during the day (maybe down to 16-18 degrees overnight), but the base temp has been around 23-25 degrees constantly. I've left the heat mat on the whole weekend and the above temps have been pretty constant all weekend.