Air Intake Question. High Or Low??

[snippetysnip]

I'll be running 8 X 6x3 flood and drain tables in a 21 by 12 foot room. Ceilings are low at 7ft.
I'm toying with the idea of running 10" solid metal ducting around the ceiling with slits cut into it to "drop" fresh air over the tables instead of from the floor.
I understand this is going against the grain but I have an experienced friend who has this setup and says it is working well....
any thoughts or suggestions welcomed..
Rough pic attached..

 

[jaybodankly]

That is 50'+ of 10" solid ducting + 2- 90 degree bends. That is a lot of money, airflow and pipe. I think by the time you get to the end of a 50' run it will be not much cool air. Not an air guy but I would run it down the center with arms branching off. Each time you have arms you reduce pipe size to keep pressure the same.
or consider breaking it into two shorter straight runs (get rid of elbows) with intake fans from opposite sides of the room.

 

[snippetysnip]

like this... I will still need two elbows.. the air in hole is already there and can't be changed unless I bring air down the chimney but I don't think that's a good idea.. I can only vent out the chimneys. There are no windows apart from the intake one.

 

[snippetysnip]

I can put the ducting on the floor or get an air sock... I'm just thinking about putting it on the ceiling to let the cool fresh air fall over the plants.. I don't HAVE too..
All input welcome as I'll be doing this on Wednesday...

 

[JMcG]

Ducting on the floor sounds like a real PITA...
Why not use those inline fans to vent out the chimney, mix up the sizes and get some negative pressure going?

 

[snippetysnip]

Ducting on the floor sounds like a real PITA...
Why not use those inline fans to vent out the chimney, mix up the sizes and get some negative pressure going?

Hi JMcG
There will be negative pressure. I'm using at least two 10" fans for air in and a 12"ISO max fan that looks more like something off a plane for extraction...
I'm just trying to configure the best air in option...

 

[hiboy]

Is this just fresh air or air conditioning
Hb

 

[JMcG]

That should do it alright, but I really think those ducts will be nothing but in the way on the floor, or up high for that matter. Put the intake down low on the wall opposing the chimney and the extraction up high on the chimney with some good oscillating fans to move air around the room. Hook this into climate controller of your choice and dial it in from there... IMO anyway...

 

[DrMcSkunkins]

Insulated flexible ducting instead of elbows

 

[snippetysnip]

Is this just fresh air or air conditioning
Hb

Hi mate, it's just outside air.. I'm in the UK so it's defo cooler than yours...

 

[snippetysnip]

That should do it alright, but I really think those ducts will be nothing but in the way on the floor, or up high for that matter. Put the intake down low on the wall opposing the chimney and the extraction up high on the chimney with some good oscillating fans to move air around the room. Hook this into climate controller of your choice and dial it in from there... IMO anyway...

The intake has to stay where it is on the drawing.. that is the only outside wall and the only window..
@DrMcSkunkins ... why insulated flexible ducting instead? Do you not think there is more friction/resistance on the inside of the "elbow" with flex duct rather than smooth metal??
Thanks for your input guys...
anymore is appreciated

 

[DrMcSkunkins]

Elbows and metal ducting are more expensive than a 25 foot box of insulated ducting, plus its insulated so less noise and heat transfer.

 

[hiboy]

Hi mate, it's just outside air.. I'm in the UK so it's defo cooler than yours...

You could install a Y where your fan pushes the air from and have one tube go to the end of the room and the other to distribute at the first part and not deal with all the extra crap
Hb