Technician reported installing a High Pressure Shut-Off Valve and insulting blankets incorrectly; with the Bleed Duct Overheat sense elements under the insulation blanket. The aircraft made an air turn back due to a Bleed Overheat problem.

Narrative

Arrived at work and my supervisor told me my job was to change the High Pressure Shut-Off Valve on the LH Air Cycle Machine; I found my references and did the job referencing the manual throughout. When I came in the next day I was told the plane had to return to field and both the bleed leaks were flagging in the system. Several people examined the area and finally found the issue was the loops behind the Shut Off Valve were installed under the insulation cover so when operated for long enough for the High Pressure Shut-Off Valve to get hot it flagged as a bleed leak event.When installing the insulation cover there are two sets of loops it has to go under; one of them is on the side and can see easily; the other is not in the visual field and is not mentioned in the Aircraft Maintenance Manual other than to make sure the insulation cover is installed under the loops.)I made sure the one I could see was not under the cover; when performing the operational check of the installation the issue did not flag and was cleared. Familiarize myself with the system more and have work double and triple checked before signing off.