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Hi All,

What is the standard size of exhaust fan opening?

Hi, there's no one-size-fits-all here though many people do that. For effective ventilation in a toilet/ bathroom, you would have to an exhaust of 8 ACPH (air changes per hour) which you can calculate as per the size of your bathroom. You can see a step-by-step guide to calculating that here http://www.wikihow.com/Calculate-CFM-for-Bathroom-Fan

and arrive at the CFM (Cubic feet per minute) of the exhaust fan that you require for your specific application. But please be aware that CFM of a fan depends on the diameter as well as the speed (RPM) of the fan and hence all fans with the same diameter donot have the same exhaust rate. You can choose your fan RPM depending on quiet or noisy a fan you can live with (higher RPM= higher noise).

Also, please bear in mind that the exhaust rate per cubic volume for a kitchen would be different from the toilet, but these days people go for exhaust hoods which are localized over your cooking range and hence eliminates the need for general ventilation of the whole kitchen. Hope that helps !!

I guess very used fan opening (hole) size is 6". Lot of people use the drill machine bits to make the hole and it would be very neat. Fan machine portion will fit into that hole and the wings would be outside. This is most suited for 5X8 toilets.

I have seen an exhaust fan where the blades would close off the opening (the blades move like an umbrella) when the fan is switched off . Is such a thing available?

Thanks all. These inputs are ideed very helpful.


My query is also about about Kitchen exhaust fan.

I was planning for a regular exhaust fan, until I saw cool ones at ACE. Some of them had a slow opening cover and had very modern look. Further the opening size varies from 4" to 6". Mosquito/insect proof ones are with louvers or jalousie - either with manual open/close, one-shot open/close or smooth open/close.

Havells Ventil-Air DX-WE is a 6" and automatic louver opening. But, they open with a phat sound; something like a small cracker. Looks like the smooth ones use some kind of thermal controller and hence a simple and smooth open/close. hindware vents MA series is one such example. But, price is about 5k for a 6" model.

Hi, I brought havell exhaust fan for bathrooms and they are fitted to the ventilation window. I brought then while getting aluminum window done. similarly you can buy one unit now and use it to get the exact spacing/opening.
the fan has luvers type cover which closes when not in operation
size of the fan will depend on size of the bathroom, i brought it from Vinayaka ent. havell dealer on kp road. around 1300 rs. and overall fan size is 20 or 22 inch i think

Dear Mahesh;
Can you provide model no. and your bathroom size where it is used. If possible, you can provide picture how is it fitted with ventilator. This may be helpful in deciding my requirement
sahu

Hi Sahu,

Please find the fan pic attached,
common bath room size is around 8x6
other two bathrooms are 10x6
I think I went for 200 and 250. I misquoted size in my last reply. I remembered the number but got confused with unit inch or mm
Model
http://www.havells.com/product.aspx?s=57

I liked it for following reason,
reasonable low wattage
minimal noise
Mosquito/insect/rainwater can't come in
within 20 to 30 sec hot water steam/smell is removed
We need to run it for only like 2 mins towards the end of using bathroom and rooms feel fresh and no need of running it throughout

Thank you Mahesh.
It is very useful info.

sahu