Wire nuts are a whole different ball game and less controversial than the screw terminals for tinned wire. But again, for the wire gauge and a current draw we are talking about, the conversation is rather pointless.
I agree that at the current we are talking it will not matter, but I would think that terminal screws could tighten down on a tinned wire with enough force that the contact points would be very conductive. It cannot be any worse than plastic wire nuts holding the two wires together. That is a 1/2hp disposal so it is close to 10 amps.
Glad you were able to avert an issue with the heater. What alerted you to a failed heater? Was it the lack of power usage on the output that the heater is connected or the temp dropped below the safe zone on the temp sensor?
It was a safe-zone alarm; I was just walking by. was lucky in the fact it only was going on for and hour or so.
Mine sends an alert to my phone and iPad when something is out of bounds. I have the temp input safe zone setup and a wattage range on my to heater outputs. I use the temp setting on the heaters as the backup and control normal on and off with the controller. I use 2 50 watt heaters and have the wattage limits set from 45 to 55 watts so as long as they are between those limits it will not send an alert. I also have a maximum on time setting for 8 hours and 30 minutes so if a heater output stays on that long it will also send an alert but does not turn off the output. I have is setup so it doesn't turn it off but just sends an alert since it is a heater.
