I have installed a lot of these controllers this year and only recently had a couple of problems with them when used on bore systems.
It seems that the smaller transformer in them may not have sufficient capacity to cope with the demands of a pump start relay and a solenoid at the same time. The controller either brings up an ‘MV err’ message immediately or runs for a short time and then cuts out. Its been tricky to diagnose the exact problem but in discussion with Shaye from Rainbird it seems that the transformer may be the source of the problem.
The controllers have worked perfectly on mains water supply systems but I hesitate to use them on bores now and would go with the Hunter X Core which has a larger transformer. Its worth knowing in case you are having similar problems!