System type: Pumped - differential controller
System is still operating.
Test of controller and sensors were positive.
Anti scald valve is leaking and stuck at set position.
Very unusual plumbing strategy. The return from the collector feeds into the cold water supply at tank just before the anti scald valve. All plumbing was ¾” copper except for a short piece of ½” copper in the hot water line to the house. Plumbing was very poorly installed. The electrical switch to the water heater was installed backwards.
The freeze valve and air vent were leaking. Metal parts of the freeze valve were severely rusted. The exterior piping was insulated but the hot return was not wrapped with aluminum foil tape and therefore starting to degrade.