Temperature, relative humidity and absolute humidity - big discussion.

Huckster79

Huckster79

Well-Known Member
You know part of dialing things in probably make different set ups w doff humidified work fine. Like Afghan running 35 whole time. W drier air plant would transpire faster thus suck more nutes up but if dialed in for that transpiration rate obviously works just fine. Then folks like me running more humid Wud transpire less so a dialed in nute mix may be stronger but replenished less often. Both are probably both roads to similar outcomes. ..
 
SPLFreak808

SPLFreak808

Well-Known Member
If you heat the room, where would all the absolute water go?

I know this chart isnt for cannabis, however I urge anyone who is having environment issues in sealed rooms to try this atleast one time! I have had very good luck with staying in range but dropping temps mid/late flower. Even @afganking is pretty much within range at 35 and claims they love it. user299140_pic892488_1338439953.jpg
 
somebody1701

somebody1701

Well-Known Member
Shugglet said:
If it is removing moisture from the air it is, by definition, dehumidifying... even without lights on, the humidity will drop with an AC chugging away.

The thing is, dehumidifiers are AC units that simply run the air back over the heating coils before putting it back into the room. This is so you can drop humidity without cooling the room as well. Its not like you cant remove humidity and cool the room at the same time...
Click to expand...
Glad to see someone else on this board actually understands how a dehumidifier works.

To all of you saying otherwise, do you see condensation on hot or cold things? If you want to dehumidify without increasing temperature, you can't just heat the air.
 
S

Shugglet

Well-Known Member
Its reefer madness.

Relative humidity is the relationship of absolute humidity and temperature. Hes failing to realize that you can change either variable, not just temperature. Likely too high when he wrote it... Perhaps a testament to his product. idk.
 
OldMedUser

OldMedUser

Well-Known Member
RH, or relative humidity, is just that. Relative to the air temp. If you raise the temp and the amount of moisture in the air remains exactly the same the RH will read lower at 80F than it did at 70F because the warmer air can hold more moisture so it is relatively drier. There is still the same amount of water in the air but it's relatively less at the higher temp. Relatively being the key word here.

How many times have you read about someone plunking an AC unit in the grow room then getting warmer temps that they started with? The AC will take heat from the air that passes through the cooling coils but if that heat isn't exhausted from the room all that happens is the RH goes down but no heat is actually removed from the room. Then you have the added heat produced by the refrigeration motor so you end up with a net increase in temp instead of the loss you were after.

Ever notice how warm the air is coming off the back of your fridge? That is from heat being removed from inside the fridge and radiated from the cooling coils on the back along with heat generated by the motor. A/C units, dehumidifiers, fridges and freezers all use the same engines and cooling systems to operate and all have the same heat issues. Keep those coils clean to work more efficiently and not only extend the life of the motor but save you electricity too.

Because an A/C is designed to cool a space and not to dehumidify, tho it does that too, it brings warm air through it's cooling coils and exhausts the heat removed out the back to the great outdoors. Along with the water that drips off the cooling coils and then drips outside too like under your car when the A/C is running. So you can see how putting a window or a portable A/C unit in the grow room without a way to direct it's exhaust outdoors is not going to work.

I've never owned a dehumid so I'm not sure if they are built to have an exhaust port that can be hooked up to direct the heat out of the room or not but you would have to do that if keeping the temps down is something else you want other than just reducing the RH. Then it will also cool the room just like the A/C does tho not as effectively.

I have the other problem with about 9 months of my year being too low RH and too cool temps. Cheap heaters and humidifiers from thrift stores are what I'm always keeping an eye out for. :)

:peace:
 
dargd1

dargd1

Well-Known Member
OldMedUser said:
RH, or relative humidity, is just that. Relative to the air temp. If you raise the temp and the amount of moisture in the air remains exactly the same the RH will read lower at 80F than it did at 70F because the warmer air can hold more moisture so it is relatively drier. There is still the same amount of water in the air but it's relatively less at the higher temp. Relatively being the key word here.

How many times have you read about someone plunking an AC unit in the grow room then getting warmer temps that they started with? The AC will take heat from the air that passes through the cooling coils but if that heat isn't exhausted from the room all that happens is the RH goes down but no heat is actually removed from the room. Then you have the added heat produced by the refrigeration motor so you end up with a net increase in temp instead of the loss you were after.

Ever notice how warm the air is coming off the back of your fridge? That is from heat being removed from inside the fridge and radiated from the cooling coils on the back along with heat generated by the motor. A/C units, dehumidifiers, fridges and freezers all use the same engines and cooling systems to operate and all have the same heat issues. Keep those coils clean to work more efficiently and not only extend the life of the motor but save you electricity too.

Because an A/C is designed to cool a space and not to dehumidify, tho it does that too, it brings warm air through it's cooling coils and exhausts the heat removed out the back to the great outdoors. Along with the water that drips off the cooling coils and then drips outside too like under your car when the A/C is running. So you can see how putting a window or a portable A/C unit in the grow room without a way to direct it's exhaust outdoors is not going to work.

I've never owned a dehumid so I'm not sure if they are built to have an exhaust port that can be hooked up to direct the heat out of the room or not but you would have to do that if keeping the temps down is something else you want other than just reducing the RH. Then it will also cool the room just like the A/C does tho not as effectively.

I have the other problem with about 9 months of my year being too low RH and too cool temps. Cheap heaters and humidifiers from thrift stores are what I'm always keeping an eye out for. :)

:peace:
Click to expand...
I have humidity issues year around. Not bad during the day, in the tent on average is about 48-50% at night it spikes to 60-70%. Temps during day I maintain 77-78 degrees, at night 71-73. During veg its perfect. Not so perfect for flower/budding. I have a dehumidifier coming in tomorrow. I plan to put it in the hall way closest to the grow room to lower humidity throughout the area 10% and try to keep most of the extra heat out of the grow room. with a decrease of 10% ambient should give me about 35% during the day, at night I will try to increase the setting on the dehumidifier to force humidity down another 10% if I can. Sounds good in theory hope it works. Really not to excited about having RH at 65-75% at lights out during flower/bud.
 
Helmut79

Helmut79

Well-Known Member
Acutally I think I got it. I just re-read all answers and from what I understand both ways work - dehumidifier and heating.

Imo it wasn't a stupid thread at all. Very nice discussion.

Thank you.
 
somebody1701

somebody1701

Well-Known Member
Afgan King said:
Try 35% I guarantee its better
Click to expand...
I don't have the A/C power to get to 35%. I live in an area that is very hot a good part of the year and humid most of the year. My room is a basement on top of a weeping spring, lol. If I ever build another grow room (would be my 3rd), I will do a better job of sealing it against water vapor.
 
Afgan King

Afgan King

Well-Known Member
somebody1701 said:
I don't have the A/C power to get to 35%. I live in an area that is very hot a good part of the year and humid most of the year. My room is a basement on top of a weeping spring, lol. If I ever build another grow room (would be my 3rd), I will do a better job of sealing it against water vapor.
Click to expand...
Ya I get ya there by no means is it necessary to get that low to have quality weed but the buds just go crazy with density and resin. I've seen bomb bud grown in all types of shit lol
 
You must log in or register to reply here.
Top