How much Ventilation do I need?

[New Holland]

Went to the hydro shop today to buy a Fan and I'm concerened that the fan he's selling me is gonna be to small. Originally (3 weeks ago) he recommended a 250mm Axial fan. Today I told him that eventually I'd need a carbon filter and asked him if I'd be better of with a Centrifugal fan. He recomended a 150mm fan, which is some what smaller. I'm worried I'm going to end up with tempreture problems.

 

The growroom is 3m x 1.5m x 1.8m = 8 m/3 or 10' x 5' x 6'= 300 ft/3

I have 3 600 watt HPS lights

Current outside temps are 25C during the day and as low as 15 during the night

[everest]

my room was a similar size nh , maybe a bit different cos i was venting a veg room & flower room together .

 

i used 2* 180 mm allvent fans on the intake .... direct from outside then to extract i used 2* 250 mm big suckers pulling stale air out and through an ozone gen ...

 

worked well with the heat , but still could of done with more air at times to keep the mold probs away

 

ev

[keepleft]

check the air flow rates of those two fans. size isnt necessarily the overall indicator. for example i have one 10inch axial which only moves about 110 lts per second. whereas i have another 10inch centrifugal which moves 900 lts per second (as its rated at 500 watts!). then i have another 12 inch axial which moves 1800 lts per second!!!! so the 150mm centrifugal could be as good as the 250mm axial. ask him what the flow rates air. personally i would suggest pay extra and get a 250mm centrifugal, as u can never too much air exchange! and also get an axial to move fresh air into your room (you dont need a centrifugal for that as the carbon filter is mounted on the air outake fan)

[ben stone]

what keepleft said... I got centrifugals woth 100mm flanges so I connect it straight onto 100mm ducting. Just easier and makes any holes you have to make smaller

 

The only issue with smaller ducting on a centrifugal is it will tend to make more noise, but a bit of insulation will solve that problem.

[Pure]

IMO your BEST option if you can afford it is going a larger centrifugal , not only because of the increased air flow , but because of the noise that small one is gonna make , you alwasy have to consider that the more air a fan pumps through a small hole the more noise it makes ,

Get yourself a 250 or 300 ml centrifugal, and then you can make up a fan controller with a light dimmer and your pumping out just as much if not mroe air with ALLOT less noise

 

This is assuming ofcourse that sound is a concern to you , but those high volocity 150ml fans sound like jet engines

[Hanky]

u can never too much air exchange!

 

True words right there!

[New Holland]

Well, from what I've read here, I can only assume that the 150 Centrifugal moves as much air as the 250 axial otherwise the Hydro shop guy wouldn't have recommend it?.

 

Noise is a concern, so yeah I would get a 250mm. I can also use it else where if I decide to go bigger. But there's one big problem....MONEY!....I'm stone motherless broke (that's why I wanna grow my own to save money). It was about $500 for the 150mm with a 500mm long filter and nearly $800 for a 250mm and filter.

 

I've read on the forums that the centirfugals are pretty noisey, so I asked him to plug it in to see how noisy it was, and it was a damn sight quieter then a Fart fan I got going in my shed right next to the neighbours fence.

 

Farrrk.....I don't know which way to go now . I've got my plants stuck in a wardrobe that's to hot and I want to get them into the growroom asap. If I wanna get the 250mm, it's gonna be another 3 weeks (my budget is $100/week).

 

It'll cost me a little more in the long run. But can I get the 150mm and if it isn't enough just get another 150mm?. That adds up to $1000 for the 2 150's (would that be the same as one 300?) as aposed to the $800 for one 250?.

 

At this stage the intake will be passive. I plan to have the exhuast installed then the lights etc, then get the plants in there. Then I'll have abit of time to save up for a 250mm axial for the inlet ($200).

 

I seem to think this Hydro guy is quoting me good prices because I'm a new customer and wants my return business. Are the pricess for the fans and filter a good price?. I don't know what brand they are, there's nothing written on them. The filters are Mountain Air. I bought 3 second hand 600watt HPS Ablite's with adjusta shades and GE Lucagrow globes for $190 each. I thought they're as good as new ones becuase they vertually look brand new. Except the brand stickers on the light shade have lifted a bit from the heat of the globe. Other then that they look brand spankers.

Edited March 29, 2006 by New Holland

[Hanky]

If you're comfortable with the noise level, just go with what you can afford. We're heading into winter so you can expect lower growroom temps anyway. You can get a bigger fan before next summer if you think you need it.

 

Do you have a Bunnings near you? They have 150mm axial fans in these wall vent kits, the kits cost over $200 dollars but the fans from the kits will fit in to the box of a $17.95 exhaust fan...... Wink wink, nudge nudge. they work great for intakes!

[keepleft]

that sounds expensive! i recently got a 500watt 250mm centrifugal which is so powerful i needed to build a massive box to quiet it down for $350.

 

i suggest u get the 250mm one and dont get the filter until u can afford it. ur not going to need the filter until the last month of flowering anyway

[New Holland]

The prices for the 150mm were $250 for the fan and $300 for a 500mm filter. Is this expensive?. I might shop around. The 200mm and 250mm were only $20-$30 difference in price. He quoted a total of about $750 or more. I didn't really listen or take in what he was saying. I nearly fell over when I heard the 7...... I might still buy the 250mm fan now and save up and buy the filter later.