R-Pro › Field cases › Air conditioning
Sizing AC BTU by Room — Measure + Correction Factors
Likely causes
Korea standard: 1 py (3.3 m²) ≈ 600 BTU + environment factors
Check: **Base**: living 6 py × 600 = 3,600 BTU → 5,000 BTU model (LG/Samsung 1.5kW). **Corrections**: ① **Ceiling >2.4m** = +10% (hotel/duplex). ② **South/West** = +15% (sun). ③ **Big window (>2 m²)** = +10%. ④ **Per person** = +400 BTU. ⑤ **PC/electronics** = +500 BTU/each. ⑥ **Poor insulation (1980s detached)** = +20%. **Example**: 8 py living + 2 PCs + poor insulation = (8×600)+1000+1.2 factor = 7,000 BTU → choose 7-8k BTU model.
What to do: **Oversized warning**: BTU > sq area = ① quick cool then frequent compressor cycle, +30% energy. ② Condensation (low ΔT > 16°C). ③ User complaint 'too cold/uneven'. **Undersized warning**: ① Full load, +50% energy, short compressor life. ② 'Not cool'. **Standard models (LG/Samsung residential)**: 7 py=5,000 BTU, 9=6,000, 11=7,000, 13=8,000, 15=10,000, 20 (living+1)=12,000. **Hotels/shops** → industrial (residential rated for living env).
Korean 'bigger is better' myth = 30% over-sized. On visit, measure py/ceiling/window/occupants 30 min → receipt 'recommended BTU + reason' (dispute prevention). New apartment py = sales area (private + common); actual living area is 70% → use real floor area.
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