It's all Plain to Sea

[mrhobbithhnet]

I've seen a few Reversing Flow SHCS built and subsequently discussed here where all things are plain to sea.

I thought I'd throw a few ideas into that thought. Check out this post:

http://plaintosea.com/phpBB2/viewtopic.php?p=1837#1837


I go into a way to do it for Round Greenhouses ala dome greenhouses. (but it applies to traditional rectilinear layouts just as well) Other than two small custom dampers (and the extra fan for the other plenum) the cost is essentially the same for the system because it doubles the fan lifetimes by only running them at half the time WHILE assuring the HOTTEST air incoming always encounters the COLDEST soils as possible (higher differentials = better exchange rates)

The idea is essentially one of having two fans, one at each of the UACT plenums, but with only one running at a time - they are sequenced so that the air direction changes on a schedule that encourages the input air encountering a larger temperature differential in the soil earlier (and therefore more effectively transferring heat) than with a traditional single fan running in one direction only.

The question is: do I do the fan swap based on soil temperature, time of day or sequence them in solar gain sensed timed series (first one, then the other as the demand cycles on and off), or set intervals etc etc. Whatever it is, it's got to be real cheap and low maintenance to be a candidate.

And while we are at, how about a fan speed controller in the package too... ie: the bigger measured soil/air differentials are, the faster the fan runs. I've been getting some feedback from folks familiar with the advances in cheap semiconductor based logic controllers - well... they are now dirt cheap! Ha ha... which means one of them and a single sensor can be programed to enable any number of devices on and off on a timed or sensor based cycle. Sounds like fun for all you wizz bangers in the woodwork...

Anywhooooo....

I've been playing with the thought of a flip/flop garage door relay circuit (every enabling fan signal energizes a fan opposite to the previous enabling signal) coupled with a periodic timed preset system reset.

Solid state adjustable increment timers are cheap, http://www.sourceresearch.com/potter/Potter-Brumfield-pdf.cfm?PdfPage=s8990dsw.pdf
hell, it could be done for less than $20 bucks that way. But is there another way, a better way to sense when a reverse flow would have the most bang for the buck? A sensor enabled flip/flop that flips the flop when there's some mileage to be gained? Another hairbrained scheme all together? What do you think? I'm all ears....
_________________
Just because it looks that way doesn't mean the Universe is about us, you or me. It's about Life.

learn | read |
locate | talk |
listen in tech | listen in humor | videoz