Can anyone point me in the direction of a distributor who holds the 75mm diameter semi rigid ducting by Airflow?
I live in London.

I've been pointed towards the climate center division of the Part centre, but the earliest they can get hold of this is 1 week. If anyone can let me know of other suppliers who might be able to get hold of it sooner than this I'd be grateful.

Thanks for your help.

Thanks for the steer,

Claire has just quoted me for the whole system which seemed pretty good. Sounds like they offer services for commissioning and technical support too, which I don't think is provided by the parts centre.

thanks,

Dave

My guess is that 53m3/h though 2 x 63 mm would be a little noisy, but I have only installed my ducting not bought the unit yet. I have used 125mm to be on the safe side. (2 supply and 2 extract in my kitchen/dinner with a wood stove)

Well I may be completely wrong, but it may be that the air needs to be moved at 0.59 m/s. Does not tell me how noisy that is though!

53/60/60 = m3/s
Pi R2 = .063x3.14 m2 (and there are 2 of them)
divide first by second gives you m/s.

Of course this could be completely wrong!

Posted By: borpin53/60/60 = m3/s
Pi R2 = .063x3.14 m2 (and there are 2 of them)
divide first by second gives you m/s.

That seem obvious when you put it like that. you should have been a maths teacher.

I get 0.037 is that m/s? in other words 0.037 meters (37mm) of air has to extract though the pipes ever second? that doesnt seem excessive. what do you think?

Posted By: Hairlocks53/60/60=0.0147
0.0315*0.0315*3.142*2=0.00312

But why 0.0315*0.0315*3.142*2=0.00312, area of pipe is .063m (63mm) /2 for radius then squared so multipy by its self then */ by pi 3.142

i get 2.36m/s when all calcs done. is this correct? if so what do you think?

OOps. just reread and saw that you have 2 extracts sharing the flow?
So there is indeed a missing factor of 2 in the above.
So you will have half that flow at each extract if they are properly balanced.
So yes, you were right at 2.4m/s
That is not nearly so bad but it will be noticeable. Doesn't seem unreasonable for a kitchen unless you want your kitchen to be silent.

Presumably the pipe beyond where they join is wider (double the area would be 90mm id to give the same velocity)?

I still think I would fit wider ducting than 63mm id if you can do so easily.
And I'd still like to hear about the internal inlet/exhaust.

ano2ew,
answered earlier questions on the other thread this is running on. The unit should be fine for your volume (by the sounds of the 150mm ducts and multiple flexi's - hence lowish pressure drop), but as I mentioned on the other thread, I'm not sure if the 276m3/h is the normal or the boost rate. My guess is it's the volumetric calc (which usually sets the flow requirement - of the various calc methods to meet regs) - which according to regs would be the 'normal' setting. However, in reality, you'll probably find this is excessive, and so you'll run at a much reduced set-back flow for most of the time.

Check what the designers say on this, because if you are expected to run at 276m3/h all the time with a further level for boost, you may have an issue. This 276m3/h rate will have the MVHR unit towards it upper end, which will undoubtedly be quite noisy, consuming a lot of power (possibly around 135W), and turning over a lot of air which will need heat input. Ideally you want to be running about half the rated 276, so there is little running noise, and power consumption around 30W or 40W.

Just a thought, but 2 extracts say on either side of the cooker hood, can give a better air-washing effect.