Sizing Exhaust for Two ASICs in a Basement Room
How heat rejection doubles when you add a second miner, and why intake placement matters more than fan horsepower.
Basement mining rooms are common in Gyeonggi Province — they offer noise isolation and stable temperatures year-round. But adding a second ASIC to a basement that already hosts one unit changes the thermal dynamics in ways that a bigger exhaust fan alone cannot fix.
The Recirculation Problem
A single ASIC pushes hot exhaust out one side. In a basement with limited cross-ventilation, that exhaust often lingers near the ceiling and gets pulled back into the intake of the same unit or a neighbour on the rack. This is manageable with one miner because the temperature delta between intake and exhaust stays within the unit’s rated operating range.
Add a second ASIC, and the shared air volume heats faster than either unit’s fans can evacuate — especially if both intakes face the same wall. We see intake temperatures rise 8–12°C above ambient within 45 minutes of dual operation.
What We Measure On Site
Seung-ho Lim’s thermal review protocol includes:
- Baseline ambient — Temperature at the room’s coolest point, away from the running miner
- Intake temperature — At the fan inlet of the existing unit after 30 minutes of operation
- Exhaust temperature — At the hot-air outlet
- Hot spot mapping — Infrared scan of walls, ceiling, and shelving around the mining area
- Projected dual-load — Estimated intake temperature with a second unit of specified wattage
Duct Sizing vs. Intake Placement
Operators often ask whether they need a larger inline fan. In roughly 60% of basement reviews, the answer is no — repositioning the intake to draw from a cooler zone (near the floor, away from the exhaust plume) solves the problem. Duct work becomes necessary only when the exhaust path exceeds three metres or includes more than two 90-degree bends.
For a typical 6-square-metre basement room with two 3,200W ASICs, we target an exhaust flow rate of 350–400 cubic metres per hour. A 150mm inline fan rated at 450 m³/h provides adequate headroom if duct resistance is low.
Seasonal Variation in Korea
Summer basement temperatures in Gyeonggi can reach 28°C ambient even without mining load. A second unit pushing intake above 40°C triggers thermal throttling on most ASIC firmware. We account for July–August peaks in every ventilation recommendation, not just spring conditions during the site visit.
Practical Takeaway
Before buying a second miner for your basement, map where hot air actually goes — not where you assume it goes. A ₩280,000 thermal review costs less than replacing a throttled ASIC that underperforms for six months.