Did a dummy run this weekend (in a howling gale ;^)
Filled the mash tun with water and set up the HERMS
I had mounted the kettle, pump, filter and speed controller on a board and then let it run to see how well it worked.
Observation #1 - the cheap and nasty Chinese thermocouple leaks like a seive with no method of stopping it happening from what I could see. This will be solved by removing the thermocouple from it's crimped housing and making a new fixing using a 6mm brass bolt drilled to accept it glued inside. That should sort that out.
Observation #2 - found that my PiD would only allow me to adjust the set temperature downwards and not up. Therefore I could only reach about 59 degrees in the mash tun when it was set to 70 degrees. I could not adjust it upwards but did manage to turn it down easily.
Post test I found an 'un-documented' setting in the PiD which limits the top temperature.
This picture shows the pump and filter plus speed controller.
After my experimenting, and once I've sorted out the thermocouple fixing, I'm happy to give it a bash with a first brew this coming weekend.