01 · Same test conditions
35 or 55 pints per day
At 80°F and 60% relative humidity, the HD55P is rated to remove 20 more pints per day. At 90°F and 90% RH, the ratings rise to 70 and 120 pints. Compare the models within the same row; the hotter, more humid test produces a different result. [1][2][3][4]
| Specification | HD35P | HD55P |
|---|---|---|
| Moisture removal | ||
| AHAM 80°F / 60% RH | 35US pints/day | 55US pints/day |
| 90°F / 90% RH | 70 pints/day | 120 pints/day |
| Airflow | 115 CFM | 153 CFM |
| Cabinet and equipment | ||
| Length × width × height | 15.2 × 11.2 × 11.4 in | 17.64 × 11.69 × 11.85 in |
| Weight | 38.18 lb | 44.4 lb |
| Built-in pump | Yes | Yes |
| Gravity drainage | Yes | Yes |
| Filter / refrigerant | MERV-1 / R32 | MERV-1 / R32 |
Manufacturer specifications and product listings. [1][2][3][4]
These ratings do not establish how quickly either unit will dry a particular crawl space. Moisture entry and site conditions still determine the load. See the crawl-space dehumidifier guide for sizing considerations.
Figures that need clarification: the HD55P specification lists both 3.51 A and 3.1 A. Its coverage claim is 1,500 sq. ft. in the specification and 1,300 sq. ft. in the store listing. Published noise figures also differ between those sources. They do not provide a consistent basis for choosing the quieter or cheaper-to-run model. [2][4]
02 · Cabinet and access
The HD35P is 2.44 inches shorter
The HD55P adds 0.49 inches in width and 0.45 inches in height. Its listed weight is about 6.2 lb higher. Those differences matter when checking an access opening and the intended support surface. [1][2]
Cabinet footprints at the same scale. This excludes hoses, electrical connections and space for airflow or service. Dimensions: specification sheets. [1][2]
Both manuals call for level support and unobstructed airflow. They advise placing the unit on supports rather than directly on a vapor barrier. Allow access to the filter and drain connections as well as room for the cabinet itself. [5][6]
03 · Drainage
The pump runs automatically
In pump mode, a float starts the pump when water reaches the trigger level. Pressing Drain also starts a manual purge. It is an additional control, not a requirement to empty the unit after each cycle. Both manuals show a maximum vertical discharge height of 19.6 ft, about 6 m. [5][6]
Pump mode
The manuals describe holding Drain for three seconds to switch drainage modes. The pump indicator lights when pump mode is selected. The gravity outlet must be plugged when using the pump.
Gravity mode
The manuals list gravity drainage as the default mode. The drain hose must run below the unit so water can flow out. Check the selected mode during installation.
Mode selection and indicator: printed pages 5 and 6. Drainage diagrams: printed pages 11 and 12 in both manuals. [5][6]
04 · Access and consumables
Leave room to reach the filter
Both current specifications list a MERV-1 filter. A shared filter rating does not establish that the replacement parts are interchangeable; check the model compatibility when ordering. [1][2]
The manuals describe an optional wired remote controller and humidity settings from 25% to 80%. Pump access requires removing a panel. Routine placement should leave the filter, controls and drainage connections reachable. [5][6]
05 · Choosing between them
Capacity first, then fit
Sentinel HD35P
The smaller cabinet and lower weight are its documented advantages. Consider it where a 35-pint AHAM rating meets the calculated load and access is constrained.
Sentinel HD55P
It provides the higher rated removal: 55 pints at AHAM. Check the larger footprint and installation access before choosing it for the additional capacity.
Affiliate links to the matching models at AlorAirCrawlspace. Check the current price, included accessories and order terms on the product page.
Documentation
Sources and scope
The sources are manufacturer documentation and current store listings. No hands-on noise, energy-use or drying-time tests were conducted. The linked manuals predate the current specifications; confirm the instructions supplied with the purchased unit.