Hi All

Just finished making my grow box and made a dual variac control with thermostat. 6"Intake/8" outake are controlled by each variac in normal conditions and at overtemp both fans go full speed.

Couple of questions though..

What level should i have the fans at approx or not go below ?

What temps do i want to be maintaining in room and try never to go above (hydro bubblers) ??

Any other tips on using variac control appreciated.

Cheers

Hi.
18c

QUOTE

24c

Cheers stealth, trying find the guide section ? Got my thermostat set at 30 !!!! Never new 20c was ideal temp.

24'c is a bit cold mate, 28'c is ideal, 20'c at night. warmer temps mean faster metabolic rate for plant. faster metabolism means faster growth. above 30'c without dosed co2 or VERY tight environmental control then plant growth slows down as the plant closes it's stomata to prevent stress from over rapid transpiration. 28'c is perfect though imo.

as for minimum speed, i always recommend not setting your variac below 35%. at this speed the fan will be barely moving though, so you shouldn't need to go this low

My 8" outake i can have at any speed no probs but my 6" intake is causing noise probs - http://www.uk420.com/boards/index.php?showtopic=198910

What should i have them set to 'about' ie both 70% ???, i presume both at same speed as one is larger than other, but how can you work out how much air is replaced in room when they are variable speed ??

Willl try to get temps at 27/28c then, i presume it's better to stay on the 'hot side' ie both fans go 100% at 30c.

Cheers

nah, i'd keep it on the cool side, too high a heat will cause more stress than being a few degrees cooler. i would worry more about temps than airflow, the amount of airflow needed to keep the air healthy and fresh, is a tiny fraction of what's needed to remove excess heat, so you should be able to turn your fans waaay down before you hit the mark where there isn't enough fresh air for your plants. just set your fans at the speed that makes the noise bearable (still want a high a flow as possible, more is always better) and set the temp to switch em both on at 30'c. obviously if you set the fans really low, then they'll be switching over to full speed more often, so a slightly higher speed may work out better than having them nice and quiet some of the time, but constantly switching on and off into jet engine mode, and it's the changing to full speed that becomes the noticeable noise. i used to get annoyed with the intake, as it makes a real loud wooshing noise. use passive intakes now, but not always practical for most grows as the area needs to be mahoosive

24 is best

Having a nightmare tbh mate. Temps hitting 30c even with fans at 80% with the intake VERY noticeable. Also humidity way down around 30%.

Still playing but worried about temps, i can easily add another 4"intake but would it help with temps, it will also allow me to turn 6" right down so can not be heard.

Also had 2 blockages and only 12 hours into first ever grow !!!

Cheers

its all trial & error

another intake wont increase airflow, but like you say it'll mean you can quieten down your 6". only way to increase airflow is with a larger/extra exhaust, as the only way to increase airflow above the rating of the exhaust fan, is to have positive pressure in your tent, which is obv no good