Ac exhaust pipe

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SamWE19

Well-Known Member
I’ve got an issue with my portable acs over heating.

Currently got an extended run of 6 inch pipe with a booster fan but it’s just not enough.

I can’t get a rigid pipe any bigger than 6 inch without literally costing nearly a 1000 usd here... it’s a rip off.

But I can get 10 inch flexible aluminium ducting.

I know flex causes friction loss so my question is for any duct experts on here what is a better option 6 inch rigid pipe with a 10 inch reducer and upgrading my booster fan to a 10inch fan on the 6 inch pipe or

Upgrade to a flexible duct 10 inch with the 10 inch extractor fan?

Logic tells me bigger pipe no brainer but I’m not sure on how much frictional loses truly are
 
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SamWE19

Well-Known Member
Well I’ve went and bought a 10 inch RVK fan and 10 inch flex ducting and I will test both. Still interested in anyone’s input though will be here by end of week so I can test it
 
Nizza

Nizza

Well-Known Member
as far as friction loss goes, long sweep 90's , hard pipe, and round is the way to go

try to have your first 90 off the fan at least 3x the size of the fan so 10" would be at least 30" of ducting before your first 90 for optimum air flow

if you want to save money hard duct it to the first 90 and do the straight runs with flex

mountin the fan vertically
 
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SamWE19

Well-Known Member
Nizza said:
as far as friction loss goes, long sweep 90's , hard pipe, and round is the way to go

try to have your first 90 off the fan at least 3x the size of the fan so 10" would be at least 30" of ducting before your first 90 for optimum air flow

if you want to save money hard duct it to the first 90 and do the straight runs with flex

mountin the fan vertically
Click to expand...
I only have the option of a 6inch rigid or a 10 inch flex.

As i can’t find a supplier of the 10 inch rigid I need.

In this situation what is better, 6 inch rigid it’s smaller but less friction or 10 inch flex larger but more friction?
 
Nizza

Nizza

Well-Known Member
10" Sheet metal pipe is cheap man. You must have a local hvac supply house that would sell you some
 
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SamWE19

Well-Known Member
Nizza said:
10" Sheet metal pipe is cheap man. You must have a local hvac supply house that would sell you some
Click to expand...
Unfortunately no as in my country literally nobody uses hvac... except maybe industrial freezers or something. summer temps get to 25c for a week or two if we’re lucky... most of the year it’s below 10c.

Cheapest I found would work out an extra 400 ish usd for the amount of duct I need.

If you think 10 inch flex really won’t work though I’ll bite the bullet and go for it.
 
Nizza

Nizza

Well-Known Member
The expanding foam will push on the flex and create more friction
I would just use the flex and control the bends, and be sure its stretch out nice in your situation. To insulate it , would only be for light leaks . The temps in the exhaust / intake ducts shouldn't be to different than the room temps if your drawing from your house or whatever (condensation)

for me to give good advice I would love to see the grow room and proposed exhaust/intakes
 
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SamWE19

Well-Known Member
Nizza said:
The expanding foam will push on the flex and create more friction
I would just use the flex and control the bends, and be sure its stretch out nice in your situation. To insulate it , would only be for light leaks . The temps in the exhaust / intake ducts shouldn't be to different than the room temps if your drawing from your house or whatever (condensation)

for me to give good advice I would love to see the grow room and proposed exhaust/intakes
Click to expand...
This is for a sealed grow room the duct is for a portable dual hose ac exhaust.

The temps can get up to 40-50c

The expanding foam would just be to seal the gaps in the rigid foam, it wouldn’t push on the flex

It’s a very tight space grow, hard to get any photos.

Vertical grow using space as much as possible 5000w of Cob leds, co2 burner and 36000 btu dual hose ac, which I have opened and ensured is air tight from the outside section and recirc section
 
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SamWE19

Well-Known Member
I’ve upgraded to the 10 inch flex and a 10 inch RVK exhaust fan.

Just waiting for all the expanding foam to dry around all my clamp joints for an extra air tight seal then I’ll run a proper test to see if they have improved. Can tell instantly that the airflow through the pipe is massively more than the smaller pipe though just by the feel of it
 
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Mak'er Grow

Well-Known Member
Just a thought...
I replaced a blower fan awhile back in a portable AC unit and found the coils were covered almost like a sweater...lol
Open your unit up and check the coils...they seem to plug up with dust and such causing less air flow and heat problems.
Good luck and happy growing :P
 
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SamWE19

Well-Known Member
Mak'er Grow said:
Just a thought...
I replaced a blower fan awhile back in a portable AC unit and found the coils were covered almost like a sweater...lol
Open your unit up and check the coils...they seem to plug up with dust and such causing less air flow and heat problems.
Good luck and happy growing :P
Click to expand...

Yeah I noticed that, there are prefilters in front of the coil I need to make sure I clean regular. It would be a shame if I have to open them up to clean as I’ve sealed them up with expanding foam

Going back into the room Soon to check on the test to see if the room has handled the temp ok
 
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SamWE19

Well-Known Member
SamWE19 said:
Yeah I noticed that, there are prefilters in front of the coil I need to make sure I clean regular. It would be a shame if I have to open them up to clean as I’ve sealed them up with expanding foam

Going back into the room Soon to check on the test to see if the room has handled the temp ok
Click to expand...
Ac units no longer over heat. I need to upgrade the air circulation as the ac units are set to 16c but the part of the room furthest from the ac is hitting 32c.

I’m mounting some air circulation fans now which should improve this
 
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