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Hello from Australia,
Thank you for producing a great magazine, I read it religiously.I am a registered domestic and commercial Builder here in Brisbane, Australia and while alot of information regarding insulation and snow is irrelevant here, a lot of building techniques are still applicable.
My business has focused on installing Domestic canopy rangehoods here over the last few years and I must say the lack of information and attention to detail on site is frightening.
Trends here are for Wok cooking ( low fat ) and this produces large amounts of steam, therefore a larger capacity rangehood is required. We have a local manufacturer that produces hoods with a 1800 cubic meter per hr capacity. These hoods are also required for Viking type stoves, wok burners with 18 btu or greater and other larger cooking appliances to get the heat out of the house.
On Page 24 of your March magazine The exterior vent you mentioned would restrict flow by up to 80%, I suggest a Maco wall vent tensioned to maximum, with a internal frog flap so as to reduce back flow, This combination should not reduce flow by more than 20%.
Here is a copy of the “copy” in my installation flyer
It is preferable that all rangehoods are ducted. Some models are made to recycle the air internally, after passing through filters. However the majority of hoods now require ducting to the exterior.
Ducting must be considered at the planning stage or, at latest the framing stage. All kitchen designs should consider the duct layout and the space required. Ducting to the ceiling cavity is a dangerous fire hazard Accepted practice is to vent to the exterior . Whether this is achieved out through the roof or through an adjoining exterior wall, both are acceptable. Duel occupancy buildings this is a mandatory Australian Standard.
New hoods can extract enormous quantities of air, 200 m;/Hr and up to 2000 m;/Hr are common. Effective size and design of the duct is critical to the proper installation of rangehoods. The duct type or construction can significantly affect the performance of a hood. Bends, deflections and the length can also alter the effectiveness of the hood by as much as 90%. Factors such as room size, height from benchtop and the appliance type should also be considered when deciding on the hood type and duct.
It is the responsibility of the client to inform the architect, builder or cabinetmaker of the type of hood selected so that installation or provision for the hood specification is made during construction.
Ensure, that all trades people on site are aware of the special and specific allowances of the hood. If necessary this needs to be drawn to the trade’s people’s attention as immediately you are aware of the hoods type
Have you allowed?
Sufficient space for a duct?
Exterior venting for duel occupancy dwellings?
Large diameter bends?
For a rangehood to extract air enough for your appliance
All steel duct construction?
Duct properly designed for your hood?
Adequate diameter for the length?
Restrictions in duct?
Cross ventilation problems
DON’T!!!
Use flexiduct.
Reduce the size of duct.
Use flammable materials for duct e.g., PVC.
Enclosed is a picture of my hood over my BBQ on our covered rear deck
Replies
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Addendum
If you are considering a down draft,don't! I have taken out more than I have ever put in because clients are unhappy with the units.
*For us Americans: 1800 cubic meter per hr = 1,060 cubic feet per minute (cfm).And I assume by 18 btu, he meant 18,000 btu/hour or 18 kbtu/hour. Typical stove top burners are in the range of 8,000 to 12,000 btu/hour.I'd be concerned about moving 1,000 cfm out of a fairly tight house. Flue gases are supposed to go up the furnace and water heater and out the flue pipe. Not the other way around. If you opened a window you'd be fine, but I'd want to check what happens to the combustion equipment if someone forgot.I agree that moving lots of air out the kitchen is 1) a great idea and 2) rarely possible with normal range hoods / ductwork. The nature of air flow in ductwork is that if you double the flow, you in increase the back pressure four-fold and the horsepower needed by 8 times. Therefore, if a large enough duct wasn't put in, a retrofit is not going to be ideal without going inside the walls. -David
*Do your hoods also supply make-up air much like our commercial hoods? Bringing the make-up air to the front lip of the hood?And also, what is the decking under that grill?
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Hello from Australia,
Thank you for producing a great magazine, I read it religiously.I am a registered domestic and commercial Builder here in Brisbane, Australia and while alot of information regarding insulation and snow is irrelevant here, a lot of building techniques are still applicable.
My business has focused on installing Domestic canopy rangehoods here over the last few years and I must say the lack of information and attention to detail on site is frightening.
Trends here are for Wok cooking ( low fat ) and this produces large amounts of steam, therefore a larger capacity rangehood is required. We have a local manufacturer that produces hoods with a 1800 cubic meter per hr capacity. These hoods are also required for Viking type stoves, wok burners with 18 btu or greater and other larger cooking appliances to get the heat out of the house.
On Page 24 of your March magazine The exterior vent you mentioned would restrict flow by up to 80%, I suggest a Maco wall vent tensioned to maximum, with a internal frog flap so as to reduce back flow, This combination should not reduce flow by more than 20%.
Here is a copy of the "copy" in my installation flyer
It is preferable that all rangehoods are ducted. Some models are made to recycle the air internally, after passing through filters. However the majority of hoods now require ducting to the exterior.
Ducting must be considered at the planning stage or, at latest the framing stage. All kitchen designs should consider the duct layout and the space required. Ducting to the ceiling cavity is a dangerous fire hazard Accepted practice is to vent to the exterior . Whether this is achieved out through the roof or through an adjoining exterior wall, both are acceptable. Duel occupancy buildings this is a mandatory Australian Standard.
New hoods can extract enormous quantities of air, 200 m;/Hr and up to 2000 m;/Hr are common. Effective size and design of the duct is critical to the proper installation of rangehoods. The duct type or construction can significantly affect the performance of a hood. Bends, deflections and the length can also alter the effectiveness of the hood by as much as 90%. Factors such as room size, height from benchtop and the appliance type should also be considered when deciding on the hood type and duct.
It is the responsibility of the client to inform the architect, builder or cabinetmaker of the type of hood selected so that installation or provision for the hood specification is made during construction.
Ensure, that all trades people on site are aware of the special and specific allowances of the hood. If necessary this needs to be drawn to the trade’s people’s attention as immediately you are aware of the hoods type
Have you allowed?
Sufficient space for a duct?
Exterior venting for duel occupancy dwellings?
Large diameter bends?
For a rangehood to extract air enough for your appliance
All steel duct construction?
Duct properly designed for your hood?
Adequate diameter for the length?
Restrictions in duct?
Cross ventilation problems
DON'T!!!
Use flexiduct.
Reduce the size of duct.
Use flammable materials for duct e.g., PVC.
Enclosed is a picture of my hood over my BBQ on our covered rear deck