In the end we got a dozen chicks.
11 of them hatched before the 21 day deadline, 1 of them just after. We left the incubator on for another 36 hours, but there was no sign of life from the remaining 6 eggs. I candled them, because we were slightly disappointed not to have got a slightly higher hatch rate. One had failed at about day 10, but the other five were all at quite an advanced stage, say day 15. That coincides with a day on which we had a power cut for about 2 hours.
Now I love the R-com 20 a lot. It’s easy to use, easy to clean, and generally a great bit of kit. But of course, when you cut the power, everything fails: the heater, the humidifier, and the fans. And I noticed that if you simulate the effects of a power cut by terminating the programme midway, the lack of air circulation means that the temperature actually rises by quite a few degrees before it starts to fall again. No doubt some parts of the incubator get hotter than others, and I suspect that these five eggs, all round the edge, suffered as a result. To be fair to R-com, the incubator resumes automatically from where it was interrupted as soon as power is restored, but damage done can’t be undone.
On a more cheerful note, we learned last year just how quickly the chicks mature. On their first night they had saucers of food and water, with marbles in the water so that they wouldn’t accidentally drown. Within a day they’ve gone to small versions of proper feeders and drinkers, which are far more hygienic!