Posted by I can't do that Dave on June 8, 2014, 6:56 pm
Hi all,
We have been given two 2200cfm fans (Lakso 20" box) and am thinking of moun
ting them in series and then fitting the assembly to the man-hole opening i
nto the ceiling crawl space. The idea is to use a timer to run them during
the night when it is cooler outside suck air through the place. They are cl
ose to the same size as the opening into the ceiling so series makes sense.
Does anyone have details on how far apart to mount them for the best effici
ency? I have been testing with a small 12v fan and voltmeter in front of th
em and moving them closer or farther apart. It does not seem to make much d
ifference to the voltage developed by the small wind-driven 12v fan on wher
e they are placed.
With one fan, the voltage generated is pretty stable at 1.47vdc. With them
in series, it is around 1.98vdc and I can't seem to find any sweet spot.
I have found this graph, which shows almost double output for a large perce
ntage of the flow volume but I am not seeing that.
http://www.greenheck.com/images/articles/fansinseriesgraph.gif
Thoughts and helpful suggestions?
Thanks
Dave
Posted by clare on June 8, 2014, 7:52 pm
On Sun, 8 Jun 2014 11:56:00 -0700 (PDT), "I can't do that Dave"
>Hi all,
>
>We have been given two 2200cfm fans (Lakso 20" box) and am thinking of mounting them in series and then fitting the assembly to the man-hole opening into the ceiling crawl space. The idea is to use a timer to run them during the night when it is cooler outside suck air through the place. They are close to the same size as the opening into the ceiling so series makes sense.
>
>Does anyone have details on how far apart to mount them for the best efficiency? I have been testing with a small 12v fan and voltmeter in front of them and moving them closer or farther apart. It does not seem to make much difference to the voltage developed by the small wind-driven 12v fan on where they are placed.
>
>With one fan, the voltage generated is pretty stable at 1.47vdc. With them in series, it is around 1.98vdc and I can't seem to find any sweet spot.
>
>I have found this graph, which shows almost double output for a large percentage of the flow volume but I am not seeing that.
>
>http://www.greenheck.com/images/articles/fansinseriesgraph.gif
>
>Thoughts and helpful suggestions?
>
>Thanks
>
>Dave
>
>
What is the rationalle for mounting them in series??
Posted by I can't do that Dave on June 9, 2014, 2:53 pm
On Sunday, June 8, 2014 12:52:49 PM UTC-7, Clare wrote:
>
> What is the rationalle for mounting them in series??
Clare, if you look at that link I provided all will be revealed.
Dave
Posted by Jim Wilkins on June 9, 2014, 3:29 pm
> On Sunday, June 8, 2014 12:52:49 PM UTC-7, Clare wrote:
>>
>> What is the rationalle for mounting them in series??
>
> Clare, if you look at that link I provided all will be revealed.
>
> Dave
http://www.greenheck.com/library/articles/42
You misinterpreted the graph. Two fans increase the pressure capacity
but not the flow rate. Either way they max out at unrestricted
Flow. The second graph shows how to increase the flow rate.
-jsw
Posted by David Lesher on June 10, 2014, 3:15 pm
> What is the rationalle for mounting them in series??
I have seen such on 1-U Dell servers, where you have no room for bigger diameter fans.
But the two fans rotate in opposite directions...
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
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>
>We have been given two 2200cfm fans (Lakso 20" box) and am thinking of mounting them in series and then fitting the assembly to the man-hole opening into the ceiling crawl space. The idea is to use a timer to run them during the night when it is cooler outside suck air through the place. They are close to the same size as the opening into the ceiling so series makes sense.
>
>Does anyone have details on how far apart to mount them for the best efficiency? I have been testing with a small 12v fan and voltmeter in front of them and moving them closer or farther apart. It does not seem to make much difference to the voltage developed by the small wind-driven 12v fan on where they are placed.
>
>With one fan, the voltage generated is pretty stable at 1.47vdc. With them in series, it is around 1.98vdc and I can't seem to find any sweet spot.
>
>I have found this graph, which shows almost double output for a large percentage of the flow volume but I am not seeing that.
>
>http://www.greenheck.com/images/articles/fansinseriesgraph.gif
>
>Thoughts and helpful suggestions?
>
>Thanks
>
>Dave
>
>