Newsletter Archive

E-News Issue #60

14 March 2003

Cooling Fans


The past summer here has been a hot one with summer temperatures 33 – 38C for several weeks. This has led me to try a number of fans to keep cool.

a) 12 & 24V MINI EXTRACTOR FANS: These are small 120mm fans similar to cooling fans on desk top computer cabinets. They use around 6W and are effective within about 1m. They are rated to move 2 to 3 cubic metres of air per minute. If you really need to economise on your power usage, they are the smallest fans available. My main criticism of them is that I have found them quite noisy, (it makes more noise than a 30W 230V type of fan).

b) DC AUTOMOTIVE FAN: These are generally made as accessories for the automobile market – commonly they are available in 12V and in 24V from specialist sources. They are around 150 – 180mm and draw 12-24 watts. They make more noise than a 230V fan.

c) CEILING FAN – 230V: All 230V type fans should be run from a sine wave inverter. They are typically rated at 60-80W. When run alone on a 1600W SE22 Selectronic Inverter, it used 53, 66 and 73 watts on slow, medium and high speed. This is remarkably efficient running alone off a large inverter. The same fan when run while the TV was on drew 21, 38 and 48 watts. This power consumption is measured on the DC side of the
inverter. In terms of cooling a room, a conventional ceiling fan would be my first choice, though they do tend to blow the hot ceiling air down on you.

d) SMALL TABLE FAN – 230V: This is a 23cm table fan with a 30W rating. Running on the SE22 Selectronic Inverter with no other load, it drew 38 and 41 watts on slow and fast speed. When run on the same inverter with the TV on, it drew 13 and 15 watts. I find this fan very good when placed 2-3m away. It is very quiet and ideal as a bed fan!

e) LARGE PEDASTAL FAN – 230V: This is a large 40cm fan rated at 55W. When run with no other loads on the 1600W Selectronic inverter, it drew 63, 66 and 71 watts on slow, medium and fast speed. When run while the TV is on, it drew 38, 41 and 45 watts.

CONCLUSION: I found both DC fans (mini and automotive) to be quite noisy, especially at night. However, they do use less power than a 230V one with no other load on the inverter.

The closer you place the fan to you, the more effective it is and therefore you can run it at a slower speed (or use a smaller fan). While this sounds rather obvious, the effect of distance is very marked. Try and work out first where you can place the fan to be close to you – then you can choose between a table, wall mounted or pedestal type.

I also ran all 3 fans at once to simulate what might occur in a home with a few bedrooms. The rating on the labels of the ceiling, pedestal and table fan added up to total of 155 watts.

When all 3 fans were run on the inverter with no other load, the power consumption was 81, 105 and 150 watts on slow, medium and high speeds. When run with the television on, the power consumption totalled 77, 85 and 107 watts.

All 230V fans appear to be an efficient load for an inverter and seem to use less than their rated power if the inverter is running another load at the same time.

* Your comments and questions are most welcome; however there is no need to send our newsletter back to us when you reply! If you would like a price or product information, please tell us which country you are from
if is not evident from your e-mail address. This allows us to assess if local GST (tax) is applicable or whether 230 volt 50HZ products will work in your country etc.*

Cheers from Dave and all the RPC crew.

Dave Lambert (Director)

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