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I am building a Huge solar heater. How big a fan will Okapi run?

posted Jul 25, 2014, 4:28 PM by Greenhill EnviroTechnologies Inc.   [ updated Jul 26, 2014, 7:12 AM ]
When building a really big heater, it is tempting to want to use one really powerful fan. Before you consider such a large fan, with such high CFM, we would suggest for you to consider having two or up to 4 of our standard fans, operating a 3 inch diameter inlet/outlet pair, each. Essentially it is like dividing up your giant heater into a few smaller, more standard-sized heaters and using an Okapi 2.i or even a combination of Okapi Systems to operate numerous fans indpendently within your giant heater.

We highly recommend you consider this kind of set-up for your system, to keep the noise-level low (if that is of concern for you), your running costs low and for ease of set-up. 

A single fan operating a very large in area solar collector, no matter how powerful it might be, will not likely be able to move all that air evenly and effectively thoughout the collector. This could result in hot pockets of low air-flow where not heat gets harvested. 

You can keep you solar air collector box wide open, or partition it into 4ft wide x 8 or 10ft high areas for each inlet-outlet section: that is up to you, the designer.

It is ideal to have independent control of the air flow in each section or partition to control the temperature within the whole solar collector system better. A very large sized collector could potentially heat up more on one end in the early part of the day, and cool down faster on the other end later in the day. Also if there are any passing shadows, you will have better control of the air flow through the sections of the heater box that could be at drastically different temperature levels.


Once you have considered this set-up, and still feel you want to order a more powerful fan(s), our Okapi systems are made to operate more powerful fans than our standard fan.

Okapi can run a fan with these requirements:
          •  4 Amps (48watts) maximum
          •  12VDC 
          •  with PWM (Pulse Width Modulation: variable speed control)
Contact us if you wish to discuss the best fan system set-up for your solar air heater.