AC box with a 6" vortex.

[OgreSeeker]

I think the air being pulled threw the ac box may already be to hot to efficiently cool the ac.
By the time the air reaches your ac box it is as hot as the air being exhausted by your ac so it's like having a box around your ac with no air flow.

 

[Guest 18340]

My , Ogreseeker is right about the air being too hot already, AND you need a bigger fan.
I'm trying to avoid the hot air issue by not dumping the hot ac exhaust into my garage.

 

[Whatever]

The sides of the AC are open so air flow through the unit should be OK if the setup was better. The AC is really getting cooled by the air from the garage. Obviously opening up the 5" exhaust to 6" would definitely help as it increases the area by about 45%...that's HUGE.

Even with that fix there's something else as others have said. The problem really gets worse when the lights go on and the AC is cycling frequently. Then you have 2 447 cfm fans dumping air into a box with only 1 447 exhaust fan (that is actually bottlenecked by that 5" exhaust opening)...YIKES! That 447 cfm exhaust fan is most likely actually only flowing about 315 cfm. You then have positive pressure in that box and the AC can't circulate air through the unit to cool at all.

Those 2 6" Vortex fans are most likely actually running about half that due to the 2 almost 90 degree bends I see and the duct length so the imbalance I outlined earlier is not as severe. The other issue is with the AC on trying to push air into that box it will add to the positive pressure issue and the hood cooling fans will work less efficiently. Since they will work less efficiently it will force the AC to work harder thus exacerbating the heat issue.

I think 447 cfm per 3 1000's is not enough taking into consideration the flow losses I've mentioned. You could always add another set of 6"ers but don't think that's the long term solution. You could do is buy a much larger fan, I like Elicients, say like a 12" 1200 cfm and split it through the 2 banks of 1000's. In the summer it'll really help to move more air through and you can dial it down a bit in the winter.

Are the two 6" fans pulling air from directly outside or from a basement area? If they pull directly from outside they will work more efficiently.

Hope that helps a bit.

EDIT - I looked at the pics again and you have a 90 degree bend on that 1 exhaust fan which adds more restriction to flow but also see the pipe you're trying to get around. The left hood cooling duct coming from the grow space has a large unnecessary bend. You should straighten that stuff out as it all adds up.

The 12" fan might be a good option if you just wanted to use 1 fan to cool the 2 banks but you might look at something like an Elicent 10" for the intake then put the 6"ers on each set of lights just before the ducting exits the grow space. Either way in the long run I think you should think about reworking that hood cooling system a bit as you're underpowered. Even when you fix the AC cooling issue the current hood setup will still cause problems.

 

[DIGITALHIPPY]

thoes 2 vents pulling the hot air from the lightsa and moving to the a/c box... i think thats the problem...
you cant use warm air to cool a hot device... it'll lose 1/2 the effeciancy like that... its simply too hot. ditch thoes 2 exhaust somewhere and pullair from the g-radge to cool the a/c... your box looks nice, and think it should work fine, that 6" might even work.

 

[hoosierdaddy]

Yeah, I agree with Whatever, those 6"ers are after the fact and should not be of concern to the function of the AC unit.
Once you get the exit path squared away, the votex' are going to run with less labor and will start performing better, and you can always add to them.

It looks like you have a straight shot from the unit to the door....
If you can manage duct like you have now all the way to the door grill, it should be cake from there. You could even put a hatch at the end and put a box fan inside.

With a duct the size of your AC box now, you have a larger path than needed, since the smallest pathway is the enclosure around the AC fan (you can take the AC enclosure off and measure what the actual diameter of the fan opening is....and that is the bottelneck). As long as your grill doesn't block too much surface area, you can probably exhaust with no additional fan. (but the cheap box fan in the duct couldn't hurt)

 

[hoosierdaddy]

thoes 2 vents pulling the hot air from the lightsa and moving to the a/c box... i think thats the problem...
you cant use warm air to cool a hot device... it'll lose 1/2 the effeciancy like that... its simply too hot. ditch thoes 2 exhaust somewhere and pullair from the g-radge to cool the a/c... your box looks nice, and think it should work fine, that 6" might even work.

He is pulling air to cool the condenser from the garage and not the 6" ducts. They are after the fact and only come into play on the exhaust side.

 

[Whatever]

The current setup to cool the AC would be fine if the exhaust flow cfm from that box matched the flow from the two exhaust fans from the grow space plus the air flow the AC is designed to move.

 

[Guest 18340]

You know what, after looking closely at your pics, i beleive the problem is that those 2 6" and the fan built into the ac are building up heat in the box faster than that that 1 6" attached to the box can evacuate. Heat is building up, so your compressor shuts down. DIGITALHAPPY is right on the money, vent those lights somewhere else, not into the ac box, and you'll be fine with that one 6" sucking the hot air outta the box.
Notice how when you pulled the back off the box the ac did its job...Thats a clue to the problem.
Wish i had looked at your pics sooner. Nice box btw.

 

[hoosierdaddy]

DH was thinking he was using the air from the ducts to cool the AC, which he is not.
The whole issue is a matter of not having the proper size ducting for the exhaust path.
Exactly what Whatever has stated.

It's what I have been saying all along in this and several other AC box threads.
The need of a larger more powerful fan only presents itself when you have choked down the path of air flow. IF the ducts are sized properly, there is not a need for an additional exhaust fan, and the existing fans will exhaust the hot airs just fine.

* On further reflection..
Be careful if you increase the size of the light fans, as there will come a point that the force they create can start to create pressure again, and could possibly put you right back to square one.
But, with the size of duct that your box is now, I think it will handle the AC fan and the Votex' as well.

 

[Whatever]

* On further reflection...

I've reflected on this setup also...lol. The whole thing boils down to thermal dynamics, airflow, etc. Yes if you disconnected the 2 ducts from the hoods that 1 447 cfm fan might be adequate to cool the AC IF there was not the 5" restriction cause it now only operates at about 315 cfm AND that 90 degree bend present right where it exits which further reduces the fans efficiency. A 90 degree bend can cut flow by as much as 50% so god only knows what that fan is actually flowing. Also if you don't create a passive or active system, even with the current setup, to allow that exhaust fan to breathe properly it'll never flow properly...it has to take that air it's exhausting from somewhere.

Using 8" ducting on a 6" fan will help reduce line resistance some but still comes down to where you're bottlenecked as that limits what's possible.

OK...he disconnects the 2 ducts then all that heat gets dumped into the garage, the heat slowly builds and the hotter air is less efficient at cooling the AC. Sure he could put a large passive vent in the garage door but that's very inefficient. Best case scenario is to directly, actively evacuate that heat via a ducting/fan combo. If you don't accommodate the pressure created by those hood exhaust fans somehow if you were to just dump them into the garage you'll just create resistance and they'll work less efficiently thus creating more heat in the grow space, and garage, thus putting more load on the AC. Even a properly designed passive system with door grills will cause the temp in the garage to climb.

He can make the hood vent system flow as much air as he wants as long as he engineers the system to handle it downstream.

One of the big problems you deal with in the middle of summer is the inlet temperature of any system, open or closed, and sometimes seems like you can't flow enough air through the room or hoods.

 

[G33k Speak]

IIRC MAX air flow through a 4 inch duct is around 140 CFM and 6inch duct will do 240ish CFM if there is no constriction.

Someone correct me on that if I'm worng, please.

I agree that the hot air prolly shouldn't be pumped into the AC.

you need 5000 BTU's per 1000W of lights if you don't vent.

but you're double dipping if you try to vent the hot air from the lights back into your AC.

 

[hoosierdaddy]

If we are going to engage in a conversation about AC boxes and such, shouldn't we have at least a slight grasp of the concept?

Folks, the man is taking in air for cooling of the condenser side (the hot coil end) from the ambient garage air...
See the vents in front of his box? THAT is where ALL the air that is going to go past the condenser coils comes from. It all goes through those vents.
The 6" ducts are coming into the exhaust box ON THE OTHER SIDE OF THE EXHAUST COILS! Why can't people see what is going on here? We keep going in circles...
I though his photos were pretty clear as to what is actually happening. If it isn't clear, maybe we should be doing more reading than posting.

Do we see his intake vents?

I may sound like a grumpy old dick, but good grief folks...it gets tiring trying to help folks with something you may know a bit about, only to have to wade through ignorant shit that keeps getting repeated.
And it is ignorant to think that the heat and air coming from his 6" light cooling ducts has anything at all do do with the dynamics of the AC unit in any way, PROVIDED he has proper exhaust ducting to carry the load. Which he doesn't.

Since he does not have proper sized ducting on the exhaust to handle the load, and the load is as Whatever stated, the CFM the AC fan creates plus what the 2 Vortex' create.

He probably has a 10-12 inch enclosure around his AC fan. That makes a 10-12 inch duct no matter how you slice it. Plus two additional 6" ducts, makes a total of about 170 sq inches.
12" duct (6 x 6)3.141= 113.07 sq in
6" duct (3 x 3)3.141= 28.27 sq in 28.27 x 2 = 56.54

113.07
+ 56.54
169.61 sq in

His box now is 18" x 27" which is a total of 486 sq in

The only reason that the heat from his light air is coming into play now is because he is trying to push 170 sq in of air through a 19.36 sq in hole.

*
I want to add a bit about the loss of flow due to 90deg turns.
IF you have a smooth bore, such as is in a water pipe, you can just about neglect the turn completely. It makes very little effect on the air flow at all.
Sure there is a blockage of sorts there, but there is also a physical phenom working there that isn't seen. All in all a smooth bore virtually doesn't reduce the air flow at all.
Smooth type ducts have very small values for frictional loss.
What builds up the resistance is flexible ducting. Flex duct is what will kill your air flow, and it should be the last thing used. But, it is easy to get and work with.

 

[Whatever]

Since he does not have proper sized ducting on the exhaust to handle the load, and the load is as Whatever stated, the CFM the AC fan creates plus what the 2 Vortex' create.

We agree on something ...just playing.

and 6inch duct will do 240ish CFM if there is no constriction.

How is that possible when a 6" Elicent fan is rated at like 300 cfm and a 6" Vortex is rated at 447 cfm? The difference in the rating here has to do with internal design/components/etc. and not the 6" inlet/outlets.

I want to add a bit about the loss of flow due to 90deg turns. IF you have a smooth bore, such as is in a water pipe, you can just about neglect the turn completely. It makes very little effect on the air flow at all.
Sure there is a blockage of sorts there, but there is also a physical phenom working there that isn't seen. All in all a smooth bore virtually doesn't reduce the air flow at all. Smooth type ducts have very small values for frictional loss. What builds up the resistance is flexible ducting. Flex duct is what will kill your air flow, and it should be the last thing used. But, it is easy to get and work with.

I gotta look into that a bit more. Flowing air, like water, does not like to make turns. Though it's more of an issue with water due to it's mass. There's turbulence that occurs in sharp bends for one. I'd think the higher the air speed and greater the air volume the more this will be an issue. Definitely smooth bore ducting is best. Anyway...will do some research. An easy way to verify this would be to pick up an airflow meter (micromanometer I guess they call em in the HVAC world). I actually looked at getting one of those awhile back and it was like $200+ I think for a decent one.

Another thing I just thought of for Y1F to control heat in that grow space is create blankets for the hoods made out of double foil covered mini bubble wrap insulating stuff like you can find at a hardware store. Soon after getting into indoor growing I created blankets for every hood...and they work great to contain heat. Another thing is to use insulated ducting but difficult in short runs due to being pretty inflexible but that stuff works great also.

 

[yamaha_1fan]

OK so basically I am trying to push a basketball through a garden hose? I was hoping the vortex would compress the air and push it out. Maybe my logic on that is whacked.

I dont think there is anything wrong with the way the lights duct into the box. The coils are being cooled by the ambient air in the room which should be cool when all that hot air is exhausted. It seems really simple, just take all the hot air and push it out.

My only option is going to be to duct it out the bottom of the garage door.

So I have roughly 170 sq inches of air to move. If I rebuild the box, and have it taper down to roughly a 15x15 square duct then continue that all the way to the garage door, would that be OK? The box will need to take two 90 degree turns with a total run of about 30 feet

It will need to run about 20 feet from the A/C to upper left corner of this pic which is a straight run along the wall. Then it will need to go 90 degrees down to the floor. Then another 90 degrees as I push it out the vents in the bottom of the door.




Could I still put the vortex in there somewhere to help with air movement or is that a waste?

 

[Whatever]

OK so basically I am trying to push a basketball through a garden hose?

Basically yes.

I was hoping the vortex would compress the air and push it out. Maybe my logic on that is whacked.

Yes your logic is whacked.

I dont think there is anything wrong with the way the lights duct into the box.

The only thing wrong is you are not evacuating enough air through that design. The concept itself is solid.

The coils are being cooled by the ambient air in the room which should be cool when all that hot air is exhausted.

The coils are not being cooled due to inadequate airflow even when the lights are off and when on and those 2 6" Vortex's you have cooling those hoods dump air pressure into that box making the situation worse.

It seems really simple, just take all the hot air and push it out.

It is simple and your current setup is totally inadequate.

My only option is going to be to duct it out the bottom of the garage door.

You know the situation better than anyone and you'll dump the exhaust where you think best.

If I rebuild the box

You don't need to rebuild the box.

Good luck!

 

[G33k Speak]

IIRC MAX air flow through a 4 inch duct is around 140 CFM and 6inch duct will do 240ish CFM if there is no constriction.

Someone correct me on that if I'm worng, please.

I agree that the hot air prolly shouldn't be pumped into the AC.

you need 5000 BTU's per 1000W of lights if you don't vent.

but you're double dipping if you try to vent the hot air from the lights back into your AC.

Let me distill it further.

Your AC is too small.

Your ducting is too small.

 

[Whatever]

Let me distill it further.

Your AC is too small.

Your ducting is too small.

I can't speak on the AC issue cause I don't have enough experience but do kind of remember that formula. He has 6000 watts cooled and 3000 not cooled so the 3k takes up 15000 of the available btu's leaving 9000 for the 6k. Is that enough? Don't know but will reiterate I think the hood cooling setup is inadequate and improvements will definitely help the situation. Maybe he does need a secondary AC at least during the heat of summer.

As for the ducting...the ducting he has is properly sized for the fans. The main issue is inadequate airflow due to undersized fans and that 5" opening is not helping but opening to 6" will not solve the problem. Using over sized ducting does help reduce resistance some but will not overcome the issue of inadequate cfms.

I think the best option to start with is:
1. Use expanding foam to seal any gaps between the AC and foamboard.
2. Determine the cfms of the cooling fan in the AC.
3. Match an inline fan to the AC. The 6" Vortex may work but maybe have to step up to an 8".
4. Get a sawzall an open that 5" hole to match the size of the inline fan, either 6" or 8".
4A. You need to create a passive or active ventilation system in the garage to provide enough air in to match the 6" or 8" exhaust fan otherwise it will not breathe properly.
5. Remove the 2 hood cooling ducts from that box and seal those holes.
6. Remove the 2 6" Vortex fans in the flower room and replace with a 12" Elicent. I'm pretty sure they have both 1098 and 1198 cfm models? Split the 12" to feed both sets of lights.
7. Move the 2 Vortex's to the other ends of those ducts and keep inside the flower room.
8. Get a speed controller and dial down the Elicent to make sure you still have positive pressure in the hoods but reduce the excess to reduce the load on the fan.
9. Cover the 1000 watt hoods in 2 layers of double foil covered mini bubble wrap including the sides.
10. Use insulated ducting in the flower room where it's feasible. No need to for that first run from the Elicent to the first hoods in each bank. Smooth out any bends and turns if possible.
11. Even on the short runs between the hoods you can create a tube with the foil bubble wrap. You still get good flexibility but also pick up great insulating properties.
12. In the garage run the two ducts from the hood cooling fans out the garage doors.
13. Cut the holes in the garage doors in the center down low and add grills/grates.
14. Buy an older car and park it in front of those openings close enough so someone can not walk between the car and door. Take the car for a drive every once in awhile. Tinker with it every now and then.
15. Then see where you're at.

I still think 447 cfm trying to cool 3 1000's is pushing it in the summer. You can step up to 8" hoods, ducting and 2 Elicent 8" exhaust fans but that only gets you 150 cfm more but the increased duct size will help some also. Don't know if the cost to benefit ratio is there with that option.

I like Elicents because they are quieter, better built IMO, and they're Italian...just like a Ferrari...lol. I had a friend install a 12" Vortex and is was crazy loud. He replaced it with a 12" Elicent and all is well. Part of the reason is the Vortex's move more air through the same size housing. I only like the 4" and 6" Vortex's...sometimes.

EDIT - DO NOT put the double foil covered bubble wrap on the non air cooled hoods if you do end up using some for the air cooled hoods. The non air cooled hoods will need to dissipate heat.

 

[Whatever]

Here's a thread I just saw that will help with your possible AC sizing issue:
http://www.icmag.com/ic/showthread.php?t=95259

 

[DIGITALHIPPY]

sounds like u should run the 2 light banks to a different exit location /OR put a couple 6"s or a 8" passive exhaust for the light vortex's to push out. 2 fans -> 1 fan...constrictions are rife.

 

[DIGITALHIPPY]

since your using the fan for the a/c to exhaust with i bet that thing could WAIL away on a 6" duct, id go grab some 12" and do it right.