6 ms·

Major function of AC is humidity control. If you have humid summers, AC will help your house to stay dryer and prevent mold and other damage. There are climates

by lxe 7y ago

Major function of AC is humidity control. If you have humid summers, AC will help your house to stay dryer and prevent mold and other damage. There are climates in which AC is essential and even the most advanced thermal and airflow design can not replace conditioning.

ZeroFries 7y ago
I was told many times to go with a slightly undersized AC, precisely for this reason - they're better dehumidifiers because they run for longer periods of time.
- duxup 7y ago
  Today that might be a bad idea. Generally most modern forced air systems are designed to run more often (for heat and cool) / longer periods of time now. On top of that you can get multi stage AC units. Mine will run at a lower setting for a longer period of time when the less efficient "full blast" stage is too much, but AC is still needed.
- hellofunk 7y ago
  Why would an undersized air conditioner be more effective? What’s the size got to do with the efficacy?
  - showdead 7y ago
    Less effective at cooling, more effective at dehumidifying (it seems there is a presumption that dehumidification is roughly linear with operating time.)
    - toomuchtodo 7y ago
      AC units also last longer if they run continually vs frequent starts and stops.
      - throw_away 7y ago
        Why not just buy a dehumidifier made specifically for this with collection bucket and all?
        toomuchtodo 7y ago
        Most folks will need an AC unit regardless, and there is already a condensate drain line from the air handler. You could get an additional dehumidifier if your use case calls for it (dehumidification without a need to cool) but the cost is non-insignificant. I have explored a dehumidifier for my Florida home, and after looking at the numbers, it just made more sense to tighten up the envelope and set the AC to 74. I have solar on the roof though, so the energy costs aren’t terribly high (vs possible mold remediation) for this approach. YMMV.
        wasdfff 7y ago
        That bucket can fill in a day and click off the machine sometimes.
        Johnny555 7y ago
        Some (all? most?) dehumidifiers can accept a hose connection in place to the collection bucket, my parents have one on a raised shelf in their basement and have the hose drain in the laundry sink -- no need to empty the bucket.
        nwallin 7y ago
        A dehumidifier is an air conditioner. It's the same device. It operates a compressor that condenses a fluid with a boiling point below room temperature. As it condenses to a liquid, it generates a lot of heat. This heat is removed from the liquid. The liquid is then allowed to boil, which pulls heat from the environment. In an air conditioner, the heat is radiated outside, and the cool air is vented inside. In a dehumidifier, the air is sucked in, blown over the cool radiator, which creates condensation which is collected, then blown over the hot radiator, and then blown back into the house. So you might as well just use an AC and be more comfortable. There aren't any upsides to using a dehumidifier.
    - bumby 7y ago
      If other variables are constant, the dehumidification is proportional to air changes/air flow. However, some of those other variables are not consistent across different designs. For example, they may use a different refrigerant that requires a different compressor. Centrifugal devices like fans and compressors use power in a non-linear fashion. Look up pychrometric chart and/or fan affinity laws for more detail
      - numismatex 7y ago
        What so many are missing is the swamp-cooler effect of dehumidification. I live in Las Vegas, and merely having more humidity inside to push outside cools, heatsinking the environment. I've got an aquarium set up half-full of water with a fan pointed at it, and cloth (old t-shirts) wicking the water upward. Evaporative cooling has saved us upwards of $50 or more a month this summer. Our electricity bill was $400 this last month, largely from air conditioning.
  - jccooper 7y ago
    It runs for a longer time; the dehumidifying function of an air conditioner (the original use, thus the name) is a function of airflow x time, and airflow doesn't change much.
    - derefr 7y ago
      Does this mean that you could dehumidify a room very quickly by just vent-ducting a blower fan to your dehumidifier? Or is there a point of diminishing returns where the air must linger for a certain time within the dehumidifier to actually have any humidity extracted? (Yes, I'm aware that such a set-up would be impractically noisy; it's just a thought experiment.)
      - CarVac 7y ago
        A dehumidifier already has its heat pump capacity minimized for its design airflow. An air conditioner has its heat pump capacity sized to cool a house, far in excess of what is needed merely to remove the humidity.
- ShakataGaNai 7y ago
  No, you're just forcing your expensive AC to run longer and run less efficiently. On the flip side, if you get a unit that's too big it'll cycle on and off too frequently - shortening the lifespan. You should get a correct sized unit for your house and space. The AC unit will last longer and use the least amount of energy. If you live somewhere that humidity is an issue - in some places that's in the winter (when you wouldn't use cooling AC) - get a whole house dehumidifier system. Ex: https://www.sylvane.com/whole-house-dehumidifiers.html https://www.sylvane.com/whole-house-dehumidifiers.html -- Those will run and maintain the correct humidity regardless of AC. Use the right tool for the right and you'll get the most efficient results.
- adrianmonk 7y ago
  If you can afford to pay more, just get a two-stage or variable-speed air conditioner. This is the exact problem they're meant to solve. They have compressors which can adjust speed, not just turn off/on like a single-stage AC compressor does. So there's a lot less worry about whether it's sized right because it basically "resizes" itself as necessary. The two-stage type has off/low/high, so it can get a lot closer to the right size. The variable-speed type is essentially continuously adjustable, so it's like always having the perfectly-sized AC unit for whatever the weather happens to be like today.
Dwolb 7y ago
Mold and other damage again is symptomatic of modern building techniques. Humans for centuries had figured out how to live without AC sustainably on most regions for earth.
- seanmcdirmid 7y ago
  Yes, but often they did that by simply living with some mold and rebuilding every few years. Just because they could live with it didn’t make it ideal.
- Loughla 7y ago
  As the other poster said - ability to do it doesn't mean it works really well. From my 96 year old grandfather: We planned to replace every piece of plaster in the wall in 10 years, and we kept hardwood floors because we could throw the rugs away and sand the floors down when the mold started to get bad. That's wasteful and time intensive. No thanks.
- kortilla 7y ago
  Yeah, they lived in moldy damaged houses in constant disrepair.
  - nikolay 7y ago
    That's not entirely true. In Bulgaria, even during the hottest summer days, you go into a traditional stonewall building and it is cool inside with no mold as walls are whitewashed. In some newer traditional houses, the first floor is dug half in the ground, which also keeps the first floor cooler in the summer and warmer during the winter, and it's where the living room typically is.
orthoxerox 7y ago
> There are climates in which AC is essential and even the most advanced thermal and airflow design can not replace conditioning. Essential? You mean these climates were completely uninhabited before the invention of AC?
- rhcom2 7y ago
  The charitable interpretation is "essential to keeping the home dry and free of mold" not "essential to live there".
charlesoliver 7y ago
can actual dehumidifier be used as a more environmentally friendly solution?
- opencl 7y ago
  If you rely on ventilation for cooling you're just constantly pulling in high humidity air from outside and the dehumidifier will do nothing.
bytematic 7y ago
AC's were invented to do humidity control mainly actually, I think the cooling was a side-effect
- timw4mail 7y ago
  For paper, or all things.

by lxe 7y ago

ZeroFries 7y ago

I was told many times to go with a slightly undersized AC, precisely for this reason - they're better dehumidifiers because they run for longer periods of time.

duxup 7y ago
Today that might be a bad idea. Generally most modern forced air systems are designed to run more often (for heat and cool) / longer periods of time now. On top of that you can get multi stage AC units. Mine will run at a lower setting for a longer period of time when the less efficient "full blast" stage is too much, but AC is still needed.
hellofunk 7y ago
Why would an undersized air conditioner be more effective? What’s the size got to do with the efficacy?
- showdead 7y ago
  Less effective at cooling, more effective at dehumidifying (it seems there is a presumption that dehumidification is roughly linear with operating time.)
  - toomuchtodo 7y ago
    AC units also last longer if they run continually vs frequent starts and stops.
    - throw_away 7y ago
      Why not just buy a dehumidifier made specifically for this with collection bucket and all?
      - toomuchtodo 7y ago
        Most folks will need an AC unit regardless, and there is already a condensate drain line from the air handler. You could get an additional dehumidifier if your use case calls for it (dehumidification without a need to cool) but the cost is non-insignificant. I have explored a dehumidifier for my Florida home, and after looking at the numbers, it just made more sense to tighten up the envelope and set the AC to 74. I have solar on the roof though, so the energy costs aren’t terribly high (vs possible mold remediation) for this approach. YMMV.
      - wasdfff 7y ago
        That bucket can fill in a day and click off the machine sometimes.
        Johnny555 7y ago
        Some (all? most?) dehumidifiers can accept a hose connection in place to the collection bucket, my parents have one on a raised shelf in their basement and have the hose drain in the laundry sink -- no need to empty the bucket.
      - nwallin 7y ago
        A dehumidifier is an air conditioner. It's the same device. It operates a compressor that condenses a fluid with a boiling point below room temperature. As it condenses to a liquid, it generates a lot of heat. This heat is removed from the liquid. The liquid is then allowed to boil, which pulls heat from the environment. In an air conditioner, the heat is radiated outside, and the cool air is vented inside. In a dehumidifier, the air is sucked in, blown over the cool radiator, which creates condensation which is collected, then blown over the hot radiator, and then blown back into the house. So you might as well just use an AC and be more comfortable. There aren't any upsides to using a dehumidifier.
  - bumby 7y ago
    If other variables are constant, the dehumidification is proportional to air changes/air flow. However, some of those other variables are not consistent across different designs. For example, they may use a different refrigerant that requires a different compressor. Centrifugal devices like fans and compressors use power in a non-linear fashion. Look up pychrometric chart and/or fan affinity laws for more detail
    - numismatex 7y ago
      What so many are missing is the swamp-cooler effect of dehumidification. I live in Las Vegas, and merely having more humidity inside to push outside cools, heatsinking the environment. I've got an aquarium set up half-full of water with a fan pointed at it, and cloth (old t-shirts) wicking the water upward. Evaporative cooling has saved us upwards of $50 or more a month this summer. Our electricity bill was $400 this last month, largely from air conditioning.
- jccooper 7y ago
  It runs for a longer time; the dehumidifying function of an air conditioner (the original use, thus the name) is a function of airflow x time, and airflow doesn't change much.
  - derefr 7y ago
    Does this mean that you could dehumidify a room very quickly by just vent-ducting a blower fan to your dehumidifier? Or is there a point of diminishing returns where the air must linger for a certain time within the dehumidifier to actually have any humidity extracted? (Yes, I'm aware that such a set-up would be impractically noisy; it's just a thought experiment.)
    - CarVac 7y ago
      A dehumidifier already has its heat pump capacity minimized for its design airflow. An air conditioner has its heat pump capacity sized to cool a house, far in excess of what is needed merely to remove the humidity.
ShakataGaNai 7y ago
No, you're just forcing your expensive AC to run longer and run less efficiently. On the flip side, if you get a unit that's too big it'll cycle on and off too frequently - shortening the lifespan. You should get a correct sized unit for your house and space. The AC unit will last longer and use the least amount of energy. If you live somewhere that humidity is an issue - in some places that's in the winter (when you wouldn't use cooling AC) - get a whole house dehumidifier system. Ex: https://www.sylvane.com/whole-house-dehumidifiers.html https://www.sylvane.com/whole-house-dehumidifiers.html -- Those will run and maintain the correct humidity regardless of AC. Use the right tool for the right and you'll get the most efficient results.
adrianmonk 7y ago
If you can afford to pay more, just get a two-stage or variable-speed air conditioner. This is the exact problem they're meant to solve. They have compressors which can adjust speed, not just turn off/on like a single-stage AC compressor does. So there's a lot less worry about whether it's sized right because it basically "resizes" itself as necessary. The two-stage type has off/low/high, so it can get a lot closer to the right size. The variable-speed type is essentially continuously adjustable, so it's like always having the perfectly-sized AC unit for whatever the weather happens to be like today.

Dwolb 7y ago

Mold and other damage again is symptomatic of modern building techniques. Humans for centuries had figured out how to live without AC sustainably on most regions for earth.

seanmcdirmid 7y ago
Yes, but often they did that by simply living with some mold and rebuilding every few years. Just because they could live with it didn’t make it ideal.
Loughla 7y ago
As the other poster said - ability to do it doesn't mean it works really well. From my 96 year old grandfather: We planned to replace every piece of plaster in the wall in 10 years, and we kept hardwood floors because we could throw the rugs away and sand the floors down when the mold started to get bad. That's wasteful and time intensive. No thanks.
kortilla 7y ago
Yeah, they lived in moldy damaged houses in constant disrepair.
- nikolay 7y ago
  That's not entirely true. In Bulgaria, even during the hottest summer days, you go into a traditional stonewall building and it is cool inside with no mold as walls are whitewashed. In some newer traditional houses, the first floor is dug half in the ground, which also keeps the first floor cooler in the summer and warmer during the winter, and it's where the living room typically is.

orthoxerox 7y ago

> There are climates in which AC is essential and even the most advanced thermal and airflow design can not replace conditioning. Essential? You mean these climates were completely uninhabited before the invention of AC?

rhcom2 7y ago
The charitable interpretation is "essential to keeping the home dry and free of mold" not "essential to live there".

charlesoliver 7y ago

can actual dehumidifier be used as a more environmentally friendly solution?

opencl 7y ago
If you rely on ventilation for cooling you're just constantly pulling in high humidity air from outside and the dehumidifier will do nothing.

bytematic 7y ago

AC's were invented to do humidity control mainly actually, I think the cooling was a side-effect

timw4mail 7y ago
For paper, or all things.