Extract Fan Selection

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I am looking for a PIR-controlled (hopefully integrated) wall mounted extract fan for a shower room.

I have used TLC's calculator:

http://www.tlc-direct.co.uk/Technical/Ventilation/Ventilation4.html which comes out at 281m³/hour.

I have looked at Greenwood's catalogues (my preferred brand) but the nearest is the 150mm fan which falls short in terms of extract rate.

Also, I can't see that it has PIR operation.

Have any of you got any ideas? Thanks!
 
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Those round fans with an iris (name escapes me, but they were mentioned here a few weeks ago in a Q about needing both permanent and switched SELV) have a PIR module, don't they?

But will it do anything except drive people mad? I've never known a PIR to remain on just because you're still in its field of detection - they all seem to need regular movement of the IR source, not just its continued presence...
 
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The Icon fans do have PIR modules available for them. But they're expensive fans and in my experience not very reliable.

Apart from that, TLC's calculator doesn't seem to make sense. I don't think building regs require such a high extraction rate as the one they give. I was thinking more of 54m³/h. (For a 3x3x2 shower/bathroom).
 
But will it do anything except drive people mad? I've never known a PIR to remain on just because you're still in its field of detection - they all seem to need regular movement of the IR source, not just its continued presence...
The sensors we have at work (360s to switch the lighting) are very sensitive to movement. I think they are also dual tech, because the slightest movement of a door will trigger them.
 
Apart from that, TLC's calculator doesn't seem to make sense. I don't think building regs require such a high extraction rate as the one they give. I was thinking more of 54m³/h. (For a 3x3x2 shower/bathroom).

Is that 15l/s? That's the minimum. But the TLC calculator makes allowance for so many air changes per hour, hence the higher figure.

Basically, I'm going for a higher figure because the room has no mechanical ventilation at the moment and is starting to grow mould. The only opening light is small & does not allow adequate air movement.

I need something that will quickly drag the moist air out of the room.

This is the nearest I can find in a standard domestic style to the 281 m³/h output needed.

http://www.vent-axia.com/products/domestic/silhouette150.asp
 
It is described as a Utility and kitchen fan. As long as it is IPX4, is there any reason why it can't be employed in a shower room in Z1? It will be RCD-protected.
 

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