Bar height = share of reports marked cold or warm in that hour, split by status. A morning spike suggests boiler recovery lag.

A single problem floor points to a riser or zone valve; uniform rates point to the central plant.

No resolved outages in this window (an outage resolves when a hot report follows cold/warm on the same tap).

None detected: no fixture repeatedly failed while another tap in the same unit ran hot.

The fixture reported cold/warm while another tap in the same unit ran hot at the same time — points at that fixture's mixing valve or cartridge, not the riser. These events are excluded from riser analysis.