AlorAir Sentinel HD90 vs HDi90: Gravity Drain or Built-In Pump?

Quick answer

Choose the HD90 when you have a reliable continuously downhill drain route. Choose the HDi90 when the practical drain point is above the dehumidifier or gravity drainage would force a worse equipment location. You are not buying extra drying capacity with the HDi90—the current AlorAir specifications rate both models at 90 PPD at 80°F / 60% RH.

View Sentinel HD90 profile →
View Sentinel HDi90 profile →

The Sentinel HD90 and HDi90 have the same published 90 PPD capacity, airflow, operating-temperature range, cabinet size and manufacturer coverage. The buying decision is mainly about condensate drainage: the HD90 is the simpler gravity-drain model, while the HDi90 adds an internal condensate pump for installations where water must be lifted to a higher discharge point.

We may earn a commission if you buy through our links. Affiliate disclosure.

AlorAir Sentinel HD90 vs HDi90 specifications

Specification Sentinel HD90 Sentinel HDi90 What it means
Normalized capacity 90 PPD 90 PPD No published drying-capacity advantage for either model at the stated 80°F / 60% RH condition.
Saturation capacity 198 PPD 198 PPD Same manufacturer saturation figure; do not compare this number with another model’s AHAM/80°F rating.
Published coverage Up to 2,600 sq. ft. Up to 2,600 sq. ft. Manufacturer context is identical; size from actual conditions rather than coverage alone.
Airflow 210 CFM 210 CFM No published airflow difference.
Operating temperature 33.8–104°F 33.8–104°F Neither model has a published low-temperature advantage over the other.
Automatic defrost Yes Yes Both are designed to manage coil frosting within their published operating range.
Drainage Gravity drain Built-in condensate pump This is the main practical difference.
Published pump lift Not applicable 14.7 ft maximum pump head* HDi90 can raise condensate where gravity cannot; measure vertical lift separately from hose length.
Built-in drain hose Plan gravity drain route 19.6 ft published hose* Hose length is not the same thing as maximum vertical lift.
Current draw 5.56 A 5.56 A Current manufacturer pages publish the same current draw.
COP 2.69 L/kWh 2.69 L/kWh No published efficiency difference in the current specification tables.
Sound pressure <58 dBA <58 dBA No published sound-pressure advantage.
Dimensions 23.2 × 15.2 × 17.7 in. 23.2 × 15.2 × 17.7 in. The pump version does not require a larger published cabinet.
Weight 67.2 lb 70.5 lb HDi90 is about 3.3 lb heavier, consistent with the added pump hardware.
Filter MERV-1; optional MERV-8 MERV-1; optional MERV-8 No meaningful published filter difference.
Warranty 6-year limited warranty 6-year limited warranty Current AlorAir program is the same class for both models; verify current terms at purchase.

Check fit and total purchase cost

Measure the access opening, installation area and filter-service space before ordering. Cabinet dimensions do not include the extra space required for airflow, duct bends or maintenance.

Compare the full installed cost

Add the unit price, required ducting or adapters, drain hose or pump, mounting hardware, delivery and installation labor. Confirm the exact model and seller package before checkout. A built-in pump still needs a suitable discharge destination.

Pay for additional capacity only when the sizing range calls for it. Between equal-capacity models, compare physical fit, drainage, required accessories and documented performance.

Warranty duration alone is insufficient: check seller eligibility, installation conditions, parts and labor coverage, freight and the return window.

*AlorAir support stated in May 2026 that the HDi90 includes a 19.6-ft drain hose and has a 14.7-ft maximum pump head. The current main HDi90 specification table identifies pump drainage but does not show the pump-head figure, so CrawlClimate labels the support source explicitly.

The HDi90 is not the “higher-performance” version in published moisture removal. Current AlorAir data gives both units 90 PPD at 80°F / 60% RH, 210 CFM airflow, the same 33.8–104°F operating range and the same 2,600-sq-ft manufacturer coverage. The built-in pump is the reason to step from HD90 to HDi90.

What actually changes between the HD90 and HDi90?

1. HD90 depends on gravity drainage

The HD90 is the simpler choice when the condensate outlet can run continuously downhill to a suitable drain or exterior discharge point. Gravity drainage has no internal pump motor to cycle, no pump-head limit to plan around and one less powered component in the condensate path.

2. HDi90 can lift condensate to a higher drain point

The HDi90 adds an internal condensate pump. AlorAir support currently states a 14.7-ft maximum pump head and a 19.6-ft supplied drain hose. Those figures solve a different problem from dehumidification capacity: they let the installation discharge water uphill within the published pump-routing limits.

Drain hose length ≠ pump lift. A 19.6-ft hose does not mean the pump should raise water 19.6 ft vertically. For a pump installation, measure the vertical rise from the unit to the highest point of the discharge route and follow the current manual/support guidance.

3. The published drying performance is otherwise essentially the same

Both current product pages publish 90 PPD at 80°F / 60% RH, 198 PPD at saturation, 210 CFM, 2.69 L/kWh COP, less than 58 dBA sound pressure and a 33.8–104°F operating range. If both units can be installed correctly, there is no current manufacturer specification showing that the HDi90 removes moisture faster simply because it includes a pump.

4. The pump adds modest weight, not cabinet size

AlorAir currently lists the HD90 at 67.2 lb and the HDi90 at 70.5 lb, a difference of about 3.3 lb. Both use the same published 23.2 × 15.2 × 17.7-inch cabinet dimensions.

Which one should you choose?

Choose HD90

You already have a dependable downhill drain

If a floor drain, sump location or exterior route can accept a continuous gravity slope, the HD90 delivers the same published 90-PPD performance without paying for an internal pump you do not need.

Choose HDi90

The drain point is above the dehumidifier

If condensate must rise to a sink, standpipe, foundation-wall exit or another elevated point, the built-in pump can make the preferred dehumidifier location practical—provided the route stays within the published pump limit.

Consider HD90 + external pump

You want the pump to remain a separate service component

A gravity-drain unit feeding a correctly selected external condensate pump can be a valid alternative. It adds another device and connection, but the pump can be replaced independently of the dehumidifier.

Three installation examples

Drain routeFloor drain 15 ft away and continuously downhillDistance alone does not require a pump if gravity slope is reliable.
Starting choiceHD90Same published dehumidification performance with the simpler drainage path.
CheckMaintain continuous fallAvoid traps, kinks and uphill sections that can stop gravity drainage.
Drain routeDischarge point 6 ft above the unitGravity cannot move condensate uphill.
Starting choiceHDi90Six feet is below AlorAir support’s currently stated 14.7-ft maximum pump head.
CheckExact hose routingVertical rise, bends and total equivalent routing still matter.
Drain routeExisting external condensate pump nearbyThe pump is already part of the installation and can be serviced separately.
Starting choiceHD90 may be enoughThere may be little reason to pay for a second internal pump if the external system is correctly sized and maintained.
CheckExternal pump capacity and safety controlsFollow both manufacturers’ installation requirements.

Does the HDi90 make more sense for a cold crawl space?

Not based on the current published temperature specifications. Both HD90 and HDi90 are listed at 33.8–104°F and both use automatic defrost. The pump solves drainage; it does not give the HDi90 a lower published operating-temperature limit. If cold conditions are the main problem, compare low-temperature specifications separately.

Compare cold-space dehumidifiers →

Does the HDi90’s built-in pump justify the extra cost?

That depends on the installation, not on a universal value judgment. If gravity drainage is easy and dependable, the internal pump may add little practical benefit. If a gravity route would force the machine into a poor location or cannot reach the discharge point at all, the pump can be the feature that makes the installation workable. Because retail prices change, CrawlClimate does not hard-code a price premium into this comparison—check current merchant pricing when you are ready to buy.

Size before choosing drainage hardware

Do you actually need the 90-PPD class?

HD90 and HDi90 solve the same capacity problem. Use your crawl-space area, humidity, sealing and temperature to verify that 90 PPD is an appropriate class before deciding whether gravity drainage or a pump fits the installation.

Size my crawl space →

Frequently asked questions

What is the difference between the AlorAir HD90 and HDi90?

The main current published difference is drainage. The HD90 uses gravity drainage, while the HDi90 includes an internal condensate pump. Their published 90 PPD capacity, 210 CFM airflow, operating-temperature range, dimensions and manufacturer coverage are otherwise the same.

Does the AlorAir HD90 have a built-in pump?

No. AlorAir currently lists the Sentinel HD90 as a gravity-drain model. If the discharge point is above the unit, use a correctly configured external condensate pump or choose a model such as the HDi90 with an internal pump.

How high can the Sentinel HDi90 pump water?

AlorAir support stated in May 2026 that the HDi90’s built-in pump has a maximum lift height of 14.7 ft and that the supplied drain hose is 19.6 ft long. Treat the vertical lift and total hose route as separate specifications and verify the current guidance for the exact unit before installation.

Can the HDi90 use gravity drainage instead?

AlorAir’s current main product listing identifies the HDi90 as pump drainage. CrawlClimate would not assume a gravity-bypass configuration unless the current manual for the exact unit explicitly supports it. If you specifically want gravity drainage, the HD90 is the straightforward model in this pair.

Is the HDi90 more powerful than the HD90?

No according to the current published dehumidification specifications. Both are rated at 90 PPD at 80°F / 60% RH and 198 PPD at saturation. The “i” model’s practical advantage here is its integrated condensate pump, not higher moisture-removal capacity.

Which model is better for a 2,000 sq. ft. crawl space?

Both have the same published 90-PPD capacity and 2,600-sq-ft manufacturer coverage, so square footage does not separate them. First verify that the 90-PPD class fits your actual moisture conditions, then choose HD90 or HDi90 based primarily on the drainage route.

Related CrawlClimate guides

DrainageBest Dehumidifiers With a Built-In PumpCompare HDi90 with other pump-equipped models and published pump-lift data.
InstallationGravity Drain vs Condensate PumpPlan the condensate route before deciding which drainage system you need.
By sizeBest for 2,000 Sq FtSee where the 90-PPD class fits among other larger crawl-space options.
Primary sources checked for this comparison

Source note: Product specifications and warranty terms can change. CrawlClimate keeps manufacturer coverage separate from normalized capacity and explicitly labels support-derived pump information rather than presenting it as a value from the main specification table.

Based on published sources. How we research and choose products.