Hacker News new | ask | show | jobs
by throw0101a 1779 days ago
Yes, there are "portable" dehumidifiers:

* https://www.goodhousekeeping.com/appliances/g27192069/best-d...

It's a matter of volume: one of the portable ones could be useful in a small apartment/condo, or (if you close the door) a bedroom. But if you have something that is 1000 sq. ft. / 100 sq. m. or larger, you may need multiple portable units. It may be simpler to just install a fixed unit and patch it into your existing ducts.

There's also the fact that you have to empty the portables, so they may stop at 'random' times until you do so. Not sure about their efficiency, given that have space-volume and weight constraints compared to a fixed whole house unit. Plus you have the noise of the unit running in your living space, compared to having it in your mechanical area.
1 comments
hollerith 1779 days ago
I don't see how what you just wrote supports your assertion that "temperature and moisture needs to be dealt with via separate mechanical systems" or answers my question, "Are there dehumidifiers on the market that aren't [essentially just] air conditioners?" but you don't have to explain if you don't want to.
link
throw0101a 1779 days ago
Sorry, misunderstood:

Yes, a dehumidifier does work on a similar principal as an air conditioner: there's a cold (metal) surface that causes condensation to remove moisture from air as it passes over.

An AC system would then take the heat that is also removed from the air and send it via a refrigerant loop to some place else (usually an outside device). A dehumidifier simply takes the extracted heat to another coil inside itself and reheats the air to (roughly) the same temperature.

The purpose of a furnace is to put heat into air, of AC to take heat out† (which just so happens to also change the RH), and that of a dehumidifier is to remove moistures while not altering temperature.

If your thermostat already reads (say) 25C, but your RH is 70% (e.g., due to a lot of cooking), then it's going to feel much higher than 25C. So do you crank the AC? You drop the temperature down to 20C, but the RH may still be 60%, and still feels too warm/muggy for you. Do you crank it to 18C? Running the AC, even though the thermostat says things are "fine", can use a lot of energy just so you can feel comfortable. There's a reason why the "humidex" / 'feels like' concept is often mentioned in weather reports: it has both psychological and physiological effects (wet-bulb 35C is a real thing).

Also note that, in winter, even if the temperature and humidity are okay, it may still feel too cold because of mean radiant temperature:

* https://www.energysolutionsnc.com/designing-spaces

* https://en.wikipedia.org/wiki/Mean_radiant_temperature

* https://en.wikipedia.org/wiki/Thermal_comfort

MRT is why people feel a "draft" near windows. There is 'extra stuff' going on the walls and windows and thermal bridging. Do a search for ASHRAE 55 for various factors that go into making a comfortable (indoor) environment:

* https://en.wikipedia.org/wiki/ASHRAE_55

† AC was actually originally created for humidity control by Willis Carrier specifically for printing, to keep the ink and paper consistent and not runny. Cooling humans was only "discovered" as a use case later.

link