Inline extractor fan

[8ball]

I am planning out a new ground floor toilet / utility room which will have a toilet, washing machine and self condensing dryer. The room itself has no outside walls so I am struggling with the extractor.

 

The best route I can take is through the wall into the garage and then outside but most of the extractor units I find are designed on the assumption that your toilet is on an outside wall and do not support running a length of 100mm ducting for a few metres.

 

I stumbled across a Airflow Aventa In-Line Mixed Flow Extractor Fan 100mm which allows for up to 6 metres of flexi pipe, is there any reason why I could not use one of these instead of the standard units.

 

http://www.rselectricalsupplies.co.uk/airflow-aventa-inline-mixed-flow-extractor-fan-100mm-9041085_9318?gclid=CJqp7__Oj9ICFYeT7QodMK4AYw

 

Am I heading in the right direction with this unit?

 

Cheers

 

 

[ProDave]

You want a radial fan, not an axial fan
 

[Nickfromwales]

25 minutes ago, ProDave said:

You want a radial fan, not an axial fan
 

Explanation please  

?

[Mr Punter]

8Ball is looking at a mixed flow fan, which should be fine.

[ProDave]

13 minutes ago, Nickfromwales said:

Explanation please

?

A "normal " fan is an "axial" fan (think of a fan blade on an axle)

 

A Radial, or Centrifugal fan generates a lot more pressure and can cope with longer runs of ducting.  Here's one: http://www.screwfix.com/p/manrose-in-line-centrifugal-shower-fan-kit-chrome-100mm/41379


 

[Jeremy Harris]

I'm with Dave on this. 

 

I bought a standard in-line axial fan kit, fitted it to around 3m of flexible duct in total, and it was useless.  Swapped it out for a centrifugal fan (easy to tell the difference, the centrifugal ones are a much larger diameter in the middle) and it worked like a dream.  Axial fans don't like working with any sort of restriction to flow, whereas centrifugal fans will run without blade stall at pretty high pressures.  Central (as distinct from in wall, single room) MVHR units all use centrifugal fans for this reason, as they are usually moving air through a fair bit of ducting.

[Steptoe]

Do not use flexible duct,  that's just pure and simply poor design.

If a fan is designed for 4" duct and you want to use flexible you need to use 16", and its still not as efficient due to 'swirl' in the pipe.

And, each 90degree bend is another 1/4 size as well, try and use 2 x 45s instead.

As above, inline centrifigual or bifuctecated is the answer, but bifuctual is probably massive overkill for a domestic, even a large domestic.

A good 4" centrifugal will work with well over 5m of 4" (solid) duct, but tbh, at that length a 6" is going to be way more efficient. 

Edited February 15, 2017 by Steptoe
of=or

[Nickfromwales]

Typically I use 2 of these, connected to one of these, then a fan such as this. 

Ive fitted this exact setup in all of my wetroom / large shower installs and with great results.

Ive used the 'dreaded' flexible ducting many times, but admittedly not for any real distance ( as I mount the fan in the ceiling usually and vent straight out the roof via a lead state and roof terminal ), again without issue. 

The centrifugal ( inline ) fans are very quiet indeed, and I've had to stick bits of A4 to the fans to demonstrate they're actually on and working.  

[Jeremy Harris]

50 minutes ago, Nickfromwales said:

Typically I use 2 of these, connected to one of these, then a fan such as this. 

Ive fitted this exact setup in all of my wetroom / large shower installs and with great results.

Ive used the 'dreaded' flexible ducting many times, but admittedly not for any real distance ( as I mount the fan in the ceiling usually and vent straight out the roof via a lead state and roof terminal ), again without issue. 

The centrifugal ( inline ) fans are very quiet indeed, and I've had to stick bits of A4 to the fans to demonstrate they're actually on and working.  

 

 

Yes, those big fans are quiet, I found.  Ours was a bit of a bodge job, as the shower was under a flat roof extension, so it was really awkward fitting the damned grill and ducting in, as I had to alternately do it from reaching as far as I could from the loft side, through a small hole where the eaves were before the flat roof was added, then reach through the hole in the ceiling above the shower.  It works very well, but really only thanks to the power of the fan (I think I used the Manrose centrifugal one) as the ducting is simply horrible, but it was the only way I could get an extract from above the shower around and out through the soffit on the non-flat roof bit adjacent to the bathroom extension. 

 

The bottom line is it works OK, in fact better than it should, and I managed to fix the fan to a rafter above the insulation, to get the right sort of gradients on the lengths of duct either side, so they can't collect condensation.

 

It was one of the "do up to sell" things I've done when tarting up the bathroom, and I didn't do as good a job as I should have, but frankly, after an hour or two struggling to get the ducting around obstructions and through 300mm of fibreglass I'd run out of patience a bit....................

 

 

Edited February 15, 2017 by JSHarris

[8ball]

Thanks so much for the info everybody, I think I'll be leaning towards the Manrose that ProDave recommended but minus the flexible ducting that's included in the pack and look for some solid duct.

 

As always cheers guys