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SDMCF · 03-09-16, 03:08 PM

You are correct that the CFM of the fans is important information but unfortunately I see no easy way to determine that. Any ideas?

My test room had an area of about 25 sq m (270 sq ft).

You are also correct that 2 fans (in series) seems to be no better than just one. I suspect that may depend on the fan design though. The fans I used seem to be better at pulling air than pushing it; maybe if one of the fans was good at pushing air I might get better results - if such fans exist.

I'm not sure what I would gain by knowing the RPMs of the fans, but I could measure that. The fans I am using are PC case fans and they have a tachometer output feed so it would not be rocket science to log RPM when I log temperature. (RPM Should be constant I guess but that is as yet unconfirmed). If I got that RPM data, how might I make use of it?

With your higher ceilings I would expect the potential payback to be greater. I do understand that running the fans might subjectively feel as if it has a cooling effect even though objectively this cannot be the case. Running the fan whilst the room is not occupied would surely better than not running it at all.

03-09-16, 03:08 PM	#15
SDMCF Apprentice EcoRenovator Join Date: Jul 2014 Location: Finland Posts: 125 Thanks: 5 Thanked 35 Times in 34 Posts	You are correct that the CFM of the fans is important information but unfortunately I see no easy way to determine that. Any ideas? My test room had an area of about 25 sq m (270 sq ft). You are also correct that 2 fans (in series) seems to be no better than just one. I suspect that may depend on the fan design though. The fans I used seem to be better at pulling air than pushing it; maybe if one of the fans was good at pushing air I might get better results - if such fans exist. I'm not sure what I would gain by knowing the RPMs of the fans, but I could measure that. The fans I am using are PC case fans and they have a tachometer output feed so it would not be rocket science to log RPM when I log temperature. (RPM Should be constant I guess but that is as yet unconfirmed). If I got that RPM data, how might I make use of it? With your higher ceilings I would expect the potential payback to be greater. I do understand that running the fans might subjectively feel as if it has a cooling effect even though objectively this cannot be the case. Running the fan whilst the room is not occupied would surely better than not running it at all.