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Best Answer Nefarious Shenanigans , 13 August 2019 - 01:53 PM

it sounds to me as though if you have smell and such leaking backwards out of your house then the high pressure variant like your drawing is what you want bro

 

just the filter to the first fan then to the second fan then out of the space, all one duct run, your choice as to where you put the second fan, but put the first one near as possible to the filter like normal

 

it's gonna probably suck doors that are ajar closed and such lol the pressure should be real strong and nothing will get around the filter, everything will go through it and out

 

EDIT: sometimes you just gotta do it and see how it runs for a day or two while the changes balance out, can always do another arrangement if it fails... I reckon it'll work good for ya mate

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#11 Dex

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Posted 13 August 2019 - 02:51 PM

it sounds to me as though if you have smell and such leaking backwards out of your house then the high pressure variant like your drawing is what you want bro

just the filter to the first fan then to the second fan then out of the space, all one duct run, your choice as to where you put the second fan, but put the first one near as possible to the filter like normal

it's gonna probably suck doors that are ajar closed and such lol the pressure should be real strong and nothing will get around the filter, everything will go through it and out

EDIT: sometimes you just gotta do it and see how it runs for a day or two while the changes balance out, can always do another arrangement if it fails... I reckon it'll work good for ya mate

Thaaaankkkksss my bratha lol sometimes it's hard for me to explain what I want I go weird way around explaining lol

But you got the answer I was looking for and thanks...

if I implode the airing cubby I'll come back and say it was a bad idea lmaooo

I'll try it tonight and see how it's goes till morning
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#12 Anonymiss

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Posted 13 August 2019 - 03:37 PM

Can you explain that again to me in stupid language please

 
Maybe ;)

TL;DR: Try it - It will probably make a difference, but unless the duct is long and bendy then because you have an oversize filter a Y-piece may be better.

Two fans in series will increase pressure but not air flow.

Two fans in parallel will increase air flow but not pressure.

In the real world, these things interact.

An analogy might be blowing through a straw - the amount of air one can get down the straw will vary depending on the size of the straw and how hard one blows.

It's pretty easy to blow gently through a straw of any size, but it becomes progessively harder to push more air down it as one blows harder and the back pressure increases, and it eventually reaches a point where one simply can't blow any harder.

Now imgaine that the straw is Y-shaped, with two people blowing into it - At first, it will be easy for both of them to blow, and the air flow out of the straw will be more than that of a single person blowing at the same rate. But when the back pressure reaches the point where one person blowing can't overcome it then the flow rate will be no better than with one person blowing as hard as they can. This is like fans in parallel (Y-piece).

Now imagine the absurd situation of a person in a sealed box blowing through a straw that passes out of the box, and another person blowing air into the box. The person in the box will be under a slightly greater atmospheric pressure than normal, so when they blow through their straw they'll be doing so with the pressure they can create plus the pressure that the person outside is adding. This is like fans in series.

Intuitively, with a large straw one doesn't need much pressure to move a decent amount of air, so putting fans in parallel is perhaps a better idea, but with a smaller straw it might be better to have them in series to generate some extra pressure.

If you had matching-sized fans, duct, and filter, and especially if the duct were of any significant length, then I reckon that putting the fans in series might be best, to overcome the back pressure. But, the news that you have an oversize filter (larger straw) does complicate things a bit because it will be able to pass more air than the smaller one (skinny straw) at the same pressure, so any increase in pressure gained by putting fans in series might not be so beneficial, perhaps even not making any difference at all if the fan is already operating at close to its maximum flow rate.
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#13 Dex

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Posted 13 August 2019 - 04:08 PM

Maybe ;)

TL;DR: Try it - It will probably make a difference, but unless the duct is long and bendy then because you have an oversize filter a Y-piece may be better.

Two fans in series will increase pressure but not air flow.

Two fans in parallel will increase air flow but not pressure.

In the real world, these tbings interact.

An analogy might be blowing through a straw - the amount of air one can get down the straw will vary depending on the size of the straw and how hard one blows.

It's pretty easy to blow gently through a straw of any size, but it becomes progessively harder to push more air down it as one blows harder and the back pressure increases, and it eventually reaches a point where one simply can't blow any harder.

Now imgaine that the straw is Y-shaped, with two people blowing into it - At first, it will be easy for both of them to blow, and the air flow out of the straw will be more than that of a single person blowing at the same rate. But when the back pressure reaches the point where one person blowing can't overcome it then the flow rate will be no better than with one person blowing as hard as they can. This is like fans in parallel (Y-piece).

Now imagine the absurd situation of a person in a sealed box blowing through a straw that passes out of the box, and another person blowing air into the box. The person in the box will be under a slightly greater atmospheric pressure than normal, so when they blow through their straw they'll be doing so with the pressure they can create plus the pressure that the person outside is adding. This is like fans in series.

Intuitively, with a large straw one doesn't need much pressure to move a decent amount of air, so putting fans in parallel is perhaps a better idea, but with a smaller straw it might be better to have them in series to generate some extra pressure.

If you had matching-sized fans, duct, and filter, and especially if the duct were of any significant length, then I reckon that putting the fans in series might be best, to overcome the back pressure. But, the news that you have an oversize filter (larger straw) does complicate things a bit because it will be able to pass more air than the smaller one (skinny straw) at the same pressure, so any increase in pressure gained by putting fans in series might not be so beneficial, perhaps even not making any difference at all if the fan is already operating at close to its maximum flow rate.

Thanks buddy lmao I get that now see how stupid I am

I wanted the second fan to assist the first fan because with filter attached will pull air slightly lower than a fan with no filter...

So my aim was to get a tru 5inch pull or better...

If I take filter off the fan the negative pressure is way better than with filter on, so I was hoping the second will increase the -pressure close to a 5 inch without a filter ..

Not sure if I wrote that right lmaoo

And Thanks so much missy for explain that in simpler words lol
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#14 Anonymiss

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Posted 14 August 2019 - 01:49 AM

If you go with fans in series then you'll get the best results by placing them at least three duct diameters apart*, and preferably with a flow straightener between them.

If it were me then I'd probably put one fan directly between the filter and duct, and the other at the far end outlet :)



*This is also true for all duct fittings and bends, etc., and it even applies to the outlets and inlets, which should be a similar distance away from any obstructions, such as walls.
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