Jump to content

how to calculate what cooker hood is needed


wsoppitt
 Share

Recommended Posts

hello , guys need a bit of advice on cooker hood. Woman wants her existing cooker hood changing because when she opens oven the smoke doesnt get extracted . Kitchen is 8m x 8m and cooker is 1100cm range , duct i assume is 6" as grill width is 7 1/4 " . how do i determine which hood to get as i dont want to install a hood and its just as useless as the previous so i look an idiot and lose money , please help . thanks wayne soppitt

Link to comment
Share on other sites

We would need the ceiling height as well. However if we presume a ceiling height of 2.5m we can work out that you need extraction to at least 2400 m3 performance per hour. The performance of the extraction should be noted in the installation documents, this is because of the recent changes to the regulations.

Link to comment
Share on other sites

Is the hood being vented to the outside or merely internally within the kitchen?

AndyGuinness

Link to comment
Share on other sites

Before you go splashing out on a new extraction fan have you checked to make sure that the filters aren't blocked?

Link to comment
Share on other sites

hello , guys need a bit of advice on cooker hood. Woman wants her existing cooker hood changing because when she opens oven the smoke doesnt get extracted . Kitchen is 8m x 8m and cooker is 1100cm range , duct i assume is 6" as grill width is 7 1/4 " . how do i determine which hood to get as i dont want to install a hood and its just as useless as the previous so i look an idiot and lose money , please help . thanks wayne soppitt

If shes getting SMOKE when opening the oven she needs to stop burning the diner!!!!!

:slap

how long is the vent duct to outside?

does it have any bends?

or is it straight though the wall????

from the oven door to the hood is probably a reasonable distance....

and I doubt you are going to find any hood that extracts at such a rate that it instantly sucks all steam into its inlet,

without some hanging in the kitchen?

:popcorn

Link to comment
Share on other sites

If there is a calculation for working this out dont bother with it, I can't remember the last time i saw a domestic cooker extract that really worked . A big problem is not the height, sq m etc but if there is no air flow into the room your not going to suck anything out.

Link to comment
Share on other sites

zeespark the hood is ducted directly out of wall ( less than 1m ).

---------- Post Auto-Merged at 19:57 ---------- Previous post was made at 19:54 ----------

There must be a calculation to follow , surely it cant be a fit and hope situation . All the hoods fitted cant just be guess work ?

Link to comment
Share on other sites

Yes there is a calculation, and under the new building regulations extraction for all rooms should be calculated. The problem we have is that all cooker hoods are not for room extraction, only cooking fumes, moisture and such. The air movement for any room is given as a standard and are about 15 for a domestic kitchen, so if we then take the dimentions of the room say 15x15 with a ceiling height of 2.5 we have a room volume of 562.5 m3, and need 15 air changes per hour, this would require a fan capable of 8348m3 per hour performance or 146.6 m3 per minute. The performance of the fan will be printed in the litrature supplied with the fan. A typical 4" fan for instance is around 101m3 per hour.

Sidewinder has just done the course that allows him to test the extraction systems in rooms, and I guess he would be able to tell you 90% of fitted extraction units are far below the required levels.

Link to comment
Share on other sites

Agreed, cooker hoods are not for room ventilation, just removal or absorbtion of cooking odors. Which is why many can be fitted to an internal wall and have a recirculating fan directing air though some replaceable carbon filters. Room ventilation and cooker odor extraction/absorbtion are two similar but different things. Could be considered similar to how some electricians confuse earthing and bonding, same sort of cable but a different function.

Doc H.

Link to comment
Share on other sites

  • 3 months later...
Yes there is a calculation, and under the new building regulations extraction for all rooms should be calculated. The problem we have is that all cooker hoods are not for room extraction, only cooking fumes, moisture and such. The air movement for any room is given as a standard and are about 15 for a domestic kitchen, so if we then take the dimentions of the room say 15x15 with a ceiling height of 2.5 we have a room volume of 562.5 m3, and need 15 air changes per hour, this would require a fan capable of 8348m3 per hour performance or 146.6 m3 per minute. The performance of the fan will be printed in the litrature supplied with the fan. A typical 4" fan for instance is around 101m3 per hour.

Sidewinder has just done the course that allows him to test the extraction systems in rooms, and I guess he would be able to tell you 90% of fitted extraction units are far below the required levels.

Thanks for that info, that's really helpful as I'm looking at getting one myself.

Link to comment
Share on other sites

Before you go splashing out on a new extraction fan have you checked to make sure that the filters aren't blocked?

Never mind the filters, check the duct.

A few years ago I spent a few months working for a kitchen cleaning company, we went to one small cafe to clean and they did comment that the extractor didn't seem to work very weel.

Not surprised, when we opened the duct up (about a 4m run with 2 bends) It took me 4 hours working with a garden trowel to fill four black binbags with congealed fat.

They did comment that the extractor was working really well the following day :)

Link to comment
Share on other sites

  • 2 months later...

If there is a calculation for working this out dont bother with it,I can't remember the last time i saw a domestic cooker extract that really worked.A big problem is not the height, but if there is no air flow into the room your not going to suck anything out.

Link to comment
Share on other sites

If there is a calculation for working this out dont bother with it,I can't remember the last time i saw a domestic cooker extract that really worked.A big problem is not the height, but if there is no air flow into the room your not going to suck anything out.

Very few, if any, kitchens are air tight. They generally have plenty of capacity for air to flow in. Often the kitchen door is rarely ever closed.

Doc H.

Link to comment
Share on other sites

Surely the way way most cooker hoods are "calculated" is by the customer's wife / lady of the house looking through the brochure and going "I WANT that one!". :)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

Terms of UseWe have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.