Methodology

How the sizing estimate is calculated

The calculator is an editorial screening heuristic, not a moisture-load calculation or a validated engineering sizing model. Its multipliers are CrawlClimate assumptions. They have not been calibrated against a published field-test dataset. The output describes an equipment class rated at 80°F / 60% RH; it does not predict how many pints a unit will remove in your crawl space.

Condition adjustments

• Height: below 3.5 ft × 0.96; above 4.5 through 6 ft × 1.08; above 6 ft × 1.15. Other heights use × 1.
• Sealing: tightly sealed × 0.92; partially sealed × 1; loosely sealed × 1.18.
• Current RH: 60–69% × 1.05; 70–79% × 1.12; 80% or higher × 1.22. Below 60% uses × 1.
• Target RH of 45% or below: × 1.05.
• Temperature below 40°F: lower band × 1.08 and upper band × 1.12. From 40°F to below 50°F: × 1.03 and × 1.08. At 50°F or above: no temperature multiplier.

Applicable factors multiply together. The endpoints round to the nearest 5 PPD, with a minimum lower endpoint of 35 PPD and a minimum band width of 10 PPD. These bands cannot establish the need for equipment from a single humidity reading. If current humidity is already at or below the target, monitor conditions before choosing a unit. Drainage changes the model shortlist, not the capacity estimate. Active leaks or standing water require attention before equipment selection.

How products enter the shortlist

The calculator recommends starting options when rated capacity is inside the estimated band and the recorded operating and drainage information supports the choice. Known temperature conflicts are excluded. Missing cooler-condition ratings, maximum-temperature data or coverage figures do not automatically prevent a recommendation. Those are buying notes, not evidence of incompatibility.

At an entered temperature below 55°F, an unknown minimum operating temperature remains an unresolved requirement. Unknown drainage, a required external pump, capacity outside the exact band, or published coverage below 80% of the entered area puts a model in the separate “extra requirement” group. That coverage threshold is an editorial screen, not a physical sizing rule. Models within 15% below the lower endpoint or 25% above the upper endpoint may appear there; these browsing margins do not prove adequate sizing.

Recommended models are ordered by closeness to the band's midpoint, with preference for adequate published coverage and cooler-condition documentation when relevant. Cooler air reduces water removal even inside a published operating range. A recommendation is a practical starting choice, not a guarantee of output at the entered temperature. Affiliate availability does not affect selection or order.

Worked checks and limits

For 1,500 sq ft, 4 ft height, 70% current RH, 50% target RH, partial sealing and 50°F, the formula returns 55–80 PPD. At 2,000 sq ft, 4 ft height, 70% current RH, 50% target RH, partial sealing and 42°F, it returns 80–110 PPD. A 120-PPD model is above that second range; unknown temperature data cannot prove compatibility. Repeat calculations should replace the previous results, and changes to an input mark the old result as stale.

Sources, evidence and updates

Use the exact-model manufacturer manual for installation limits, the dated specification sheet for ratings, and the product listing for package contents. Keep 80°F / 60% RH, 65°F / 60% RH and saturation figures separate. If a source conflicts or a revision is unclear, label the field as unverified until the exact model is confirmed. Product records provide source links and verification notes; a partial source check does not reset the whole record's verification date.

Specification research is not hands-on testing. Any future test should state the model revision, equipment source, instruments, measurement conditions, duration, raw results and limitations. Purchased, borrowed or supplied equipment should be disclosed. A calculator regression check establishes software behavior; it does not validate physical sizing accuracy.

Commercial independence

Affiliate availability does not enter calculator screening or sorting. Published specifications and the reader's conditions determine the shortlist. Prices, delivery, return policies and warranty eligibility must be checked at the selected seller. No purchase or savings result is inferred from an outbound click.