Best for
- Crawl-space owners choosing between two AlorAir capacity classes
- Basements where continuous drainage is available
- Buyers who want capacity stated at AHAM conditions
Watch for
- Square-foot coverage is not a moisture-load calculation
- The HD90 is physically larger
- Both models need a planned drain path
HD55S: compact 55 PPD AHAM capacity
AlorAir lists the Sentinel HD55S at 55 pints/day under AHAM conditions and 120 pints/day at saturation, with coverage up to 1,300 ft².
The current Wi-Fi version uses gravity drainage, moves 130 CFM and measures 19.2 × 12.2 × 13.3 inches. That compact footprint is useful where crawl-space clearance and service access are limited.
HD90: 90 PPD AHAM for larger moisture loads
The Sentinel HD90 is listed at 90 pints/day AHAM and 198 pints/day at saturation, with coverage up to 2,600 ft².
It uses gravity drainage and measures 15.2 × 23.2 × 17.7 inches. The larger capacity is the reason to buy it; there is little value in stepping up if the smaller unit already handles the actual moisture load.
Choose from moisture load first, square footage second
Coverage numbers are useful for rough shopping, but crawl-space moisture varies with climate, soil moisture, vapor barriers, air leakage and water intrusion. A wet 900 ft² crawl space can be a harder job than a dry 1,400 ft² basement.
Fix bulk-water problems and encapsulation defects first. Then choose enough dehumidification capacity to maintain the target relative humidity without forcing the unit to run continuously at the edge of its capacity.
Use the same basis across brands. Room-size claims, operating-cost assumptions and moisture ratings can use different methods. Normalize the inputs before comparing products.