We had some mould appear in our bathroom and I suspected that our inline extractor fan was underpowered. As it happens the extractor just stopped working, so I'm in the market for a replacement.
I have a few questions:
- What is better – centrifugal or induct? It looks like the centrifugal ones have best throughput but are they as reliable etc?
- What rate is good? I can't find info on my old induct 23W fan's rate, but I assume it was in the range 80-100 m^3/hr – does that sound about right? Would going up to a 220 m^3/hr be excessive?
- Does power affect anything other than the rate?
A few notes:
- The inlet in the bathroom is in the ceiling
- I don't really want to take out the old ducting & fittings, so if it was a round, 125mm fan that would be great. Also 100mm would work I guess as I could still make the ducting fit.
- Fan needs to have an adjustable timer on it so it stays on after the light is turned off – there is a permanent live circuit available.
- Bathroom is approx 1.6m x 2.5m x 2.2m (i.e. 8.8 m^3) Using some recommendations from another answer, this would mean 70 m^3/hr would be fine… but it's not worked out that way before. Perhaps the timer wasn't on for long enough? Or perhaps I can double the throughput and halve the time?
Best Answer
In the end I went for a mixed flow (which I think is both cetrifugal & radial or something), has about double the throughput that is recommended for the size of room (240 m^3/hr vs 110 m^3/hr). Doesn't have a timer on it, but it seems to be keeping the steam down when we shower anyway.
Here's a link to the fan I bought in the end.
Thanks for the pointers.