Whole house dehumidifiers

What they actually are

A portable dehumidifier conditions the air in the room it is standing in. A whole-house unit is plumbed into the ducting, so it conditions the air the whole system moves - either drawing from and returning to the main trunk, or ducted independently to specific problem areas like a basement or a crawl space.

Practically, that means it runs on a humidistat somewhere central, drains to a permanent condensate line, and you never see or empty anything. The trade-off is that it is a fitted appliance: it needs duct connections, a drain, power, and somebody who knows how to size and commission it.

The efficiency case, from the certified data

This is the part that is genuinely persuasive, and it is measurable rather than a sales claim. The ENERGY STAR certified product list carries 24 whole-home models. Their Integrated Energy Factor - liters of water removed per kilowatt-hour - runs from 2.22 to 3.26. The 50-pint portable class median is 2.01, and the very best certified portable reaches 2.20.

The best-performing certified unit in the entire dataset, portable or ducted, is a Santa Fe model at 127.5 pints a day and IEF 3.26. For scale: that is roughly two and a half times the capacity of a 50-pint portable at about 1.6 times the efficiency per liter. Nothing you can put on a basement floor comes close.

The pint ratings here changed too, and by less

The same 2019 DOE test change that cut portable ratings applied to whole-home units, but the effect was smaller because these were already tested closer to their real operating conditions.

So an older 120-pint whole-home unit is about a 100-pint unit on today's scale - a 17% haircut, against the 25 to 30% portables took. If you are comparing a quote against an older spec sheet, that is the adjustment. The full explanation of the change.

When one is genuinely worth it

• More than two or three rooms have the problem. At that point you are buying, siting, emptying and listening to multiple portables, and the ducted unit starts to look tidy rather than extravagant.
• The house has ducted HVAC already. The install is far simpler when the ductwork exists. Without it, you are paying for duct runs as well as the machine.
• You want it invisible and unattended. No unit in a corner, no bucket, no hose across a floor, no machine to remember. For a finished basement or a whole-home humidity problem this is the actual appeal.
• Humidity is a year-round structural problem rather than a summer nuisance - a house that is persistently over 60% is a different case from a basement that is damp in August.
• You are already replacing HVAC. Adding it during an existing job is dramatically cheaper than doing it as a standalone visit.

When it is the wrong purchase

• One damp room. A 50-pint portable at around 488 W solves a single-basement problem for a fraction of the cost and installs itself. The basement roundup.
• A rental, or a house you are leaving. It is a fixture. It does not come with you.
• Water is getting in. A ducted unit runs against a leak exactly as uselessly as a portable does, for considerably more money. Gutters, grading and a working sump come first.
• An unheated crawl space or garage. These are conditioned-space appliances. A low-profile crawl space unit is the right product there. Crawl spaces.
• You want it this weekend. This is a quote, a lead time and a fitter.

What we cannot tell you, and will not guess

The installed price. It depends on the unit, whether ductwork exists, how the condensate is run, local labor rates and whether it is bundled into other work. Every number you find quoted online for this is either a different house or a guess, and we are not going to add another one.

What we can tell you is the running cost, because that is computable from published data. A 65-pint certified unit like the Aprilaire E080 or Carrier's equivalent draws about 545 W:

That is more per hour than a portable, because it is a bigger machine doing more work. Per liter of water removed it is cheaper, which is what the IEF advantage means in practice. Work it out at your own rate.

Questions worth asking a contractor

1. 1What is the DOE-rated capacity, at 65F and 60% RH? Not the saturation figure. If the answer is a number without a condition attached, ask again.
2. 2Is it in the ENERGY STAR certified list, and what is its IEF? Both are public, so this is checkable rather than a matter of trust.
3. 3Is it ducted to the whole house or to the problem area? These are different jobs and different sizing.
4. 4Where does the condensate go, and what happens if that line blocks? The failure mode of a permanently installed unit matters more than a portable's, because nobody is watching it.
5. 5Does it have its own humidistat, and where will that sit? A sensor in the wrong place controls the wrong room.

We have not installed one of these, we have not tested one, and we have no commercial relationship with any of the brands named on this page. What is above is the published certified data and the reasoning that follows from it. How we work.