12-VDC Blowers

For the same cfm, by increasing the power the pressure increases. The characteristics of a blower also vary with the rpm. Find those characteristics to get the job well done.

After you read this link http://en.wikipedia.org/wiki/Centrifugal_fan#Forward-curved_blades the choice is yours.

Thanks guys! I tried Googleing this, but as we know "Garbage in, garbage out". This is most useful info in an area I know not a thing about, or even where to start looking, apparently. I'll start fresh on my search, but anybody else that has 2 cents worth will be appreciated.

I have found something like this that might help you to understand; it is a torrent download ebook. http://search.utorrent.com/search.php?q=piano%20music&e=http%3a%2f%2fwww.mininova.org%2fsearch%2f%3futorrent%26search%3d&u=1 It is about water pumps but apart from some issues like cavitation and NPSH it can be applied to centrifugal blowers also. Or at least you can get familiar with some characteristics.

I would just add a point here. Your higher powered fan here would give you theoretically power static pressure for the same power consumption (assuming that it just does not have the same efficiency than the first and so consuming more power to do the same thing...). But it can be stated when you think about the fan itself. As I understood, you have an enclosed system that imposes a pressure load in your fan exhaust at the specified flow rate. If your new fan has the same flow rate, it does not matter if it is capable of a higher static pressure, because the pressure will be a result of the system restrictions, what will remain the same. For me, observing this description without knowing the details of your air flow path, it sounds like energy waste. Unless the new fan is capable of a higher flow with the same pressure (what is indeed reasonable, as far as I remember about pressureXflow fan curves).

I have yet to view the information from Nikolay above (Thank you Nikolay), but you have gotten to the crux of the matter. The major ducting restriction concern is that the thermal mass channel is broken into many compartments under the floor in order to diffuse the airflow, thus more even heating into the corners from essentially one supply and two return ducts @ 60-80° F. The return ducts go to a distribution manifold to spread out along the base of the collector wall (14' by 16" @ 60° angle.) the hotter air (100-160° F) then is collected in the plenum for return to the heat sink in a continuous loop. I feel that the extra pressure would help overcome these restrictions and help reduce the effects of air leaks from a tight but imperfect ducting system. If the air temperatures of the supply and return converge from the differential, I will be getting optimal heat saturation in the thermal mass. Yes? Any way, that's what I 'think' will happen. What's your take on this logic?

Now I see what is the problem. The thing is that the pressure drops as the flow rises. So your blower should have maximum pressure at almost zero flow, and vice-versa. In your installation it does not work either at rated flow or rated pressure. It is somewhere in between.

The second thing to remember is that if you got leaks, the pressure drop in the installation is just the effect. The cause of this is the loss of flow. The leaks increase the flow and so the pressure drops. To overcome this you need to increase the flow, and not the pressure. A pressure increase results in a leak rate increase - lost energy. So either check the ducting system or increase the flow for overcomning the loses. And in addition the heat transfer is done thanks to the flow. The pressure just keeps this flow.

Thanks Nicolay, So I will search further for higher flow with improved elecrical efficiency.

Carl