System operation is operating. It is strongly suspected that flow in the collector loop (perhaps including the water heater plumbing) is restricted due to extreme mineral scale build up.
Anti scald valve was stuck.
Insect residue in controller enclosure.
Evidence of drip from the drain valve in the collector feed line. A solidified chunk of mineral was coming from the drain valve port. Suspect there could have been a very minimal leak that eventually calcified.
Section of pipe near ceiling penetration is not insulated. Escutcheons should have been used.
Insulation protected by foil tape. Some sections of foil tape are losing their adhesion and coming off.
Sealing of pipe flashing and collector mounts with roof tar like material was done pretty sloppily.
Air vent outlet port is becoming calcified.
Long sections of sensor wiring is not secured.