Well small steps I guess. I had 1 pullet lay in the nest box this morning; 5 used their usual back corner, 1 taking a break. I will wait some days before I start to encourage the others to use it.
A friend has a Infrared Thermometer that I will borrow for the week to check on heater function. However, when I went out this morning the outside temperature was 0C, temperature inside the coop was 5C. The thermometer is mounted on the wall immediately above the new nest box and may have been influenced by the heater, I was surprised at the difference but reminded myself that there is 15 full sized birds inside as well. I also felt the heater itself and I can feel heat in all three legs, seemed about the same in each one, I did not try to measure.