Ventilation idea and questions - any experts on ducting??

I have two tents to ventilate. The nice modern brushless fans don't come small enough to suit having one for each tent - the smallest, 6" fan is more than adequate for the two even if I ran the lights at the same time but I'm not - i run one when the others off so even the 6" will be overkill but thats fine because it could cope if I add another tent to the array in future.

So Im thinking how to duct the tents to one exhaust. I think a Y piece and a couple of damper/balance valves would work IF I can automate the balance valve for each tent to open when the light in that tent goes on. Can you get motors to actuate them that can be run on the light timer? like motorised valves on central heating pipes that?

OR is there another way to do it?

Spaventa said:

I have two tents to ventilate. The nice modern brushless fans don't come small enough to suit having one for each tent - the smallest, 6" fan is more than adequate for the two even if I ran the lights at the same time but I'm not - i run one when the others off so even the 6" will be overkill but thats fine because it could cope if I add another tent to the array in future.

So Im thinking how to duct the tents to one exhaust. I think a Y piece and a couple of damper/balance valves would work IF I can automate the balance valve for each tent to open when the light in that tent goes on. Can you get motors to actuate them that can be run on the light timer? like motorised valves on central heating pipes that?

OR is there another way to do it?

Click to expand...

yea google zone dampers.

you should consider steel duct and long radius elbows from your Y transition into the tents.

the traditional symmetrical Y transition is extreemly rough on static pressure losses when you let one of the air volumes drop to 0.

get the deepest angle transition that you can find...30 degrees minimum i would say. you want a conical 'Y" or straight section 'y'.

the Y's you see at home depot are trash 45 degree fittings with flat backs and big triangular shaped transitions.

keep your losses as close to identical into each tent as is possible... and try to keep your velocity below 600 if possible. dynamic losses are a function of velocity... so if you need to go up one size in duct then do it.

a symetrical a splitter vane transition would be a better solution, but i could not even begin to explain to you how to build one over text, let alone how to actuate it. if you want to get balls deep into fabrication i can give you some pointers, but im guessing you dont want to do that.

to clarify, you want something like this:



NOT this:



please note... the first pic is of some fancy dust extraction piece, note the rolled flanged. these pieces are made for those high end dust and fume extraction systems with the ring clamp joints that allow you to take shit apart... you certainly dont need anything that fancy.

I have a small worship here with drill press, mig welder and such so not afraid to improvise, adapt etc.
I saw the actuators you can buy but they expensive - it would be cheaper to buy a second fan and have huge redundancy in the system. I cold live with that but id rather find a more efficient solution since theres already enough redundancy using one 62 fan for 2 small tents.
If we can figure out how I can get these balancers to move on time for minimal cost, that would be ideal.

Heres the things I want to automate.. CHEAPLY. Its just a motor really? isn't it?



and here are their Y pieces




This universal synchronous motor should work. With a clever linkage to both dampers, one would do. 9.99 free delivery. A spring holds the dampers in one position, one damper open, one shut then, when the motor gets juice off one of the light timers, it switches the dampers positions.

depending on the actuator, yea they are literally just gear motors with limit switches.

some have internal potentiometers for floating operation, but most dont.

if you want to build something, by all means do so man, but i would not even mess with gear motors if i were going to build something so simple... i would just build a blast gate type damper with those shitty chinise linear actuators you see on ebay for 15 bucks.

the problem with the circular dampers is you will need to buy your own little oilite bushings and come up with your own gear train to couple the gear motor to the damper.

have you looked on ebay for used damper actuators though? i bet you could get some used belimo actuators for less than you think.

Yeah I checked them first - they aren't that cheap even used.

I realised the dampers need their own motors so I can run the tents with any light schedule, not just 12/12 in both alternating.
This simplifies the linkage a lot - basically the pinion gears drive the spindles direct if position correctly, i just need to attach them with pieces of plate ill cut and drill and add a gear/cog to the spindle.

The Y and dampers come to 40 and the syncrons are 10 each. The rest I probably have already.

This one exhaust is going to do all the ventilation on its own for 3 tents - 2 x flowering 4x4x6.5 and a smaller veg/mother tent. All passive intake. The veg tent will be exhausted with a small diameter duct that "T"s in between the Y and the fan, permanently pulling a little from the veg tent.

The idea is that because bigger fans are more efficient and quieter, using the biggest fan you can is desirable and the way to do that, I think is to have a setup where a single big fan drives the whole ventilation system. The fans control temp sensor will be positioned where the Y converges so it all automates for my set temp.
Adjusting the balance with the veg tent is done by adjusting the passive intake to suit but once its set it shouldn't need further adjustment with season etc.

The grow shop will tell you to buy 6 fans and 3 controllers for about 600 to run 3 tents - shitty 4 or 5" hummers that rattle too after a few months. A really good silenced, digital brushless 8" with digital thermo controller is only 300. Smaller is always crappier and more expensive due to the economy of scale etc.

yea you could probably just use the gear motor to run a crank with articulated linkages to each of the dampers.... sort of like how old cars had the throttles set up at the intake damper things.

you could also probably just run a crank arm with cable linkages. ive built a few "remote" dampers that use lawn mower throttle cable. it works just fine for smaller single blade dampers but watch your angles. as you approach 180 degrees the linkage will start to fail unless the cable conduit is very very close to the pivot pin

How about a small air pump and a balloon\inflatable beach ball? Stuff it in a fitting,box, or piece of duct. Use a couple cheap timers to control the pumps.

Drop That Sound said:

How about a small air pump and a balloon\inflatable beach ball? Stuff it in a fitting,box, or piece of duct. Use a couple cheap timers to control the pumps.

Click to expand...

you might think thats a joke solution, but they actually used to do something similar way back in the day...

even the control signal was pneumatic btw.