Dehumidifier

Researching a dehumidifier for a small apartment bathroom with only overhead fan ventilation (that is, no exterior windows).

TERMS

• Humidity = amount of water vapor in the air (measured in grams?)
• RH = relative humidity, the percentage of water vapor present, relative to the maximum amount a given space can hold, at a given temperature
• Hygrometer = only measures and displays humidity (via)
• Humidistat = both measures and controls humidity...may or may not have a display (via)
• Adsorption = water molecules stick to the surface
• Absorption = water molecules enter material
• Hygroscopic = (of a substance) tending to absorb moisture from the air

HUMIDITY BASICS

• Fundamentals, including an image showing how relative humidity decreases when the amount of water vapor remains constant while increasing temperature
• The recommended average relative humidity level is between 35% and 45% (via)
• RH above 50% can promote bacteria growth (via)
• Misconception: Amount of water vapor which can enter a space depends on temperature and not on contents of the space...for example, a vacuum can hold the same amount of water vapor as air, at a given temperature...it depends on pressure of water vapor at a given temperature...not that we have a vacuum in our apartment...

BATHROOM DEHUMIDIFIERS

• 1 or 2 pint-per-day models not enough (via)
• 25 pint-per-day models seem to represent the next step up...really over-kill, however (via)
• Humidistat allows unit to remove water quickly, then stay off the remainder of the day (via)
• Drains
• Bathtub
• Toilet
• Tank
• Under seat
• Sink
• Other (?)

TYPES

• Desiccant, passive (for example, DampRid)
• Calcium chloride flakes, anhydrous
• Desiccant, powered (for example, EcoSeb DD122EA)
• Refrigeration

DESICCANT VERSUS REFRIGERATION DEHUMIDIFIERS

• At colder temperatures, desiccant works a bit better, as getting down to 40% RH requires chilling refrigerant coils to around 30 degrees Fahrenheit, which causes frost build-up, which means more costly anti-frost measures needed (via)
• Climates in which temperatures typically fall below 65 degrees Fahrenheit may require the purchase of a dehumidifier designed for low temperature operation (via)
• Refrigerant dehumidifiers work more efficiently at higher temperatures and higher relative humidity (via)
• Desiccant dehumidifiers may consume more electricity
• Reddit
• "How to dehumidify your room without an expensive dehumidifier?" (via)

OTHER

• Nothing on TheSweetHome
• Top 10 Reviews seems to only review larger, 70 pint-per-day models
• Ecoseb is made by Ecoair, which is based in London, UK (via)
• Ecoseb Simple and Ecoseb Classic differ in the control mechanisms: manual and electronic, respectively

BRANDS

• Keystone
• DeLonghi
• Soleus
• Comfort-Aire
• Friedrich
• Danby
• Haier
• Frigidaire
• Sunpentown
• GE
• EdgeStar

UPDATE:

We went with the EcoSeb DD122EA-SIMPLE Desiccant Dehumidifier, 15-Pint, White, 120V. I liked the idea that it does not need refrigerant. It has a lot of high reviews. Also, a simple plastic tube to the toilet tank means no maintenance. I actually preferred the simple version, since it has a simple turning dial and functionally seems about the same, save for the electronic shut-off timer. I do not care for the ionizer. For our use case, we put it in our bathroom, run it on high while taking a shower, and turn it back to normal after a bit. We leave it on eco-mode the rest of the day. The warm air blowing out the top feels pleasant and the barely noticeable smell does not bother us, at all. Runs reasonably quiet. Very pleased--would highly recommend, if your use case seems similar.