I hope this is the right place to ask a question like this.
I am building a solar heating solution for my workshop. It consists of
a heated cavity, a series of pipes and fans to push the air down to
the heat store (large volume of stone) and another fan to return the
air to collector as it will still be above ambient temperature.
All things equal, I was wondering about the fans: There will be two
working together; one pushing the into the store, one pushing the air
back into the collector. As this is a (mostly) sealed system, these
fans will compliment each other. The plumbing is 68mm PVC gutter
downpipes. I chose that because it's wide ID, cost and east of use. As
it happens, I have a couple of 60mm PC style fans (http://
As the pipes ID is 61mm, filing down the corners on the fans makes a
nice tight fitting round fan.
The fans have the following job:
1) Push cool (heavy?) air up from the store into the collector. This
is a head of about 1.7m (About 5"6).
2) Push hot (light?) air down into the bottom of the store. This would
be around 1.9m. Also, a small amount of pressure is needed here as it
has to force the air through a series of holes.
My question is this: If I find the fans do not have enough muscle,
would simply adding another fan at each end, in series, help? The
reason I would like to do this is because it's simple. Simply shoehorn
another fan into the pipe.
Drawback is double the current. As this setup runs on batteries and a
solar panel, I need to be conservative.
My second option is to build a box which will house a bigger fan and
connect that into the pipe. This is not ideal / neat. Also, larger fan
still means more current.
Finally, does proximity matter if in series? Butting the two pans
together, they become very noisy. Turbulence I imagine. Spaced around
100mm apart, they become "normal" noisy.
Thanks for any feedback.