4 X 400W grow room - Need advise please!

Hi guys, let me break it down.
Room dimensions are 270cm x 220cm x 290cm. Want to have 4, 400W hps lights inside. I calculated that i need a airflow of about 520m3/hr. Is that right? Exchanging air 30 times an hour? Or is that overboard?
Plan is to have a sea of green under each light (minimum of 10 plants under each light). Plants will be clones and will be veged for about 10-15days and then flowered.
The part im having trouble in is the fan and filter size. Fan will be a TD silent. I know they are not as powerful as the "vortex" versions but this needs to be as silent as possible.
I was quoted by a supplier that for me to achieve my calculated airflow I need a TD silent size of 800-200 (8" i think) which does 2780 rpm on high and 2480 on low setting(880m3/hr on high and 700m3/hr on low) He calculated that with a static pressure of 230Pa. BUT he said I need to find out how much static pressure of the filter is, to be sure. The filter I will have to import as they do not sell in my country. But no where on any filter models/brands does it state what static pressure it is...
For intake i was recommended the TD silent 500/150 (think this is equivalent of a 6" size) - This i guess is fine?
outside ==Fan(150)==growroom - Filter=Fan(200)==spare room which has a vent for air to slowly disperse out of.

I need some advise if this is all correct.
I'm no expert in growing. Only got about 4 harvest (cupboard grows) under my belt.

Have a great weekend guys!

2.7x2.2x2.9=17.226x60=1033.56m3/h for once a minute air exchange.

Then we need to add 20% for the restriction a filter places on a fan.

20% of 1033.56=206.6+1033.56= 1240.272m3/h

So to summarise if you listen to your own calculations you are under powering your fan.


This fan power with 400w lights should be fine.

If you were using 600w-1000w we would be adding a further 15% per light to remove the heat.

In a setup such as this you will more than likely require an intake fan too. This should be 10% less than your exhaust or more.

So an intake fan of around 700-1000m3/h should be fine.


Unfortunately this size grow is gonna generate noise regardless of what you try to do.



J

A filter should be rated for slightly more m3/h than your fan.

A filter capable of 1300m3/h is perfect.


J

Hi jondamon, thanks very much for the info, much apreciated! Question, why did you multiply by 60? I thought the air exchange would be 30 times an hour maximum.. Or have i been miss informed?

is once a minute air exchange really needed? light will not have cooltubes, just normal birdwing reflectors.

Anything between 1-3times per minute in air exchange.

If you have to exceed 3x then AC is a must due to over ventilating.

IMO you need at least 1x per minute which is the 60.


Anything less is asking for trouble.



J

I use 480m3/h fan with my 400w and it keeps everything in check.

If you do the 30 times an hour and kit yourself out for that what happens when it doesn't cool it enough in warmer weather???

Granted my 480m3/h fan is slightly overkill in winter so I use a thermostatic fan speed controller for running it.



J

Thanks J These are the specs of the fans http://fans.co.za/images/td silent 2.pdf If I go with your calculations, and my understanding of the pressure graghs, it looks like these fans will not be strong enough with a filter..Is that correct? Or do you think its do able?

Don't forget though that you can have more than one fan as exhaust.


To get to your required m3/h spread it over 2 fans and 2 filters.

It would help your temperature if you have 2 fans exhausting anyway.

One taking care of the heat in between each set of 2x400w.

If you wanted to use the fans linked I would say get yourself 2xTD800/200.

Match them up to 2 filters that are capable of handling 900m3/h each and you should be golden!



J