Cooling Notes from a Daejeon Facility Visit
What we measured when intake temps hit 34°C in a Jung-gu storage-room conversion.
In early August we assessed a six-unit half-rack installation in a converted storage room near Jung-gu, Daejeon. The operator reported hash-rate falling each afternoon despite no hardware changes. Ambient room temperature was the culprit — but not in the way they expected.
The Setup
- 6U half-rack shelf with four active units (0.08–0.12 TH/s class)
- Single window with indirect sunlight from mid-afternoon
- No dedicated exhaust fan; reliance on room air exchange via a single ceiling vent
Measurements
| Time | Room ambient | Shelf intake | Shelf exhaust | Avg hash-rate vs rated |
|---|---|---|---|---|
| 09:00 | 26°C | 28°C | 41°C | 98% |
| 14:00 | 31°C | 34°C | 49°C | 91% |
| 17:00 | 33°C | 36°C | 52°C | 87% |
The units were not failing. They were throttling because intake temperature exceeded their internal fan curve design point.
Remediation We Recommended
- Install a rear-shelf exhaust fan ducting hot air toward the ceiling vent
- Add reflective film to the window receiving afternoon sun
- Insert blanking panels on the two empty U-positions to stop short-circuit airflow
The operator implemented items 1 and 3 before our follow-up visit. Afternoon hash-rate recovered to 95% of rated output.
Broader Lesson
Daejeon summers push room ambient above 30°C in unconditioned spaces. Compact rack shelves amplify that by 3–6°C at intake. Budget for either room-level cooling or shelf-level exhaust before adding more units.