vents always have a turn, otherwise they'd need to go through the roof. makes sure its venting to the outside, not just into a soffit, or that the soffit has an inset grill where the vent exits and that its not half painted closed. my contractor ended up snipping out half of the metal strips in the grill to get a good result with a brand new vent fan.

Two mandatory requirements apply
to all kitchens: (1) makeup air is
limited to maximize transfer air, and
(2) short-circuit hoods are not allowed.
Short-circuit hoods inject more than 10%
of unconditioned makeup air directly
into the hood rather than into the
space. Recent research has found that
these hoods require higher airflows to
effectively contain smoke, increasing
overall energy use.

In larger kitchens, ASHRAE
Standard 90.1-2010 limits the volume of
air for kitchen exhaust to an appropriate
but not excessive level. Larger kitchens
must also meet one of three energy
efficiency requirements: (1) use 50%
transfer air, (2) use variable speed hood
fans, or (3) use exhaust heat recovery.
The variable speed fan option or demand
ventilation system (DVS) includes controls that sense temperature and smoke under
the hood and vary the speed to maintain
safe and effective kitchen exhaust. The
DVS must be applied to 75% of total hood
flow, must be able to reduce exhaust
flow to half, and must modulate makeup
airflow. Controls maintain hood airflow
at the levels needed to capture and
contain smoke, effluent, and combustion
products. Performance testing verifies
proper operation of the DVS. Also, this above might change slightly depending on city codes.

In other words: As long as the ventilation is good and functioning, you should be fine. As for the actual hood part, as long as the hood is able to fit in the ventilation part that is in the wall, you should be fine. It should be a standard fan and companies really try to keep those connections standard.

I would get a general contractor out there to take a peek inside the wall to make sure that there are no obstructions and make sure that the functionality of the vent are pristine. It shouldn't cost much to have a contractor look at it, and/or fix it should it need to be fixed.

Disclaimer: We are not a general contractor and not licensed to be one. The above is just from our knowledge from working in this field over the years, and dealing with building codes frequently. Be sure to check your state and city's building codes to make sure you are following them. You can also call your city and ask for the building department who will be able to tell you where to find them. :-)

Good luck!

Laura, you usually don't need to pay attention to all that technical jargon.

ASHRAE 90.1 is a US standard that provides minimum requirements for energy efficient designs for buildings EXCEPT FOR low-rise residential buildings (houses). It is also a buzz term they use often in the LEED program to justify not making something else as energy efficient as it should be.

An external blower mounted in the outside exhaust hood will be the best, and quietest for pulling air out of the home if you can find one that fits the size duct you have. Ducts often have bends in them. It does effect the airflow a bit, but a little larger CFM fan will help. You probably have a basic fan with about a 200 CFM rating. In the US, you can go up to 400 CFM without needing to worry about make-up air. (Canada is around 126 CFM depending on different situations) If you get a range hood that is rated above 400 CFM, the make-up air requirements can get expensive.

Here are the much simpler single family residential codes.

http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_15_sec003.htm

Laura. Tumo Designs focuses on LEED certified design, so the information we provided is just that. You don't "need" to focus on LEED design or energy efficient design. However, here is the link for which we got the information that might be helpful. The site is a government site which is a very reputable source for the information provided.

https://www.energycodes.gov/sites/default/files/documents/cn_kitchen_exhaust.pdf

As I said, "Copyright, 2010, ASHRAE, Atlanta, Georgia. ASHRAE/ASHRAE/IES Standard 90.1-2010: Energy Standard for Buildings Except Low-Rise Residential Buildings. Reproduced with permission. All rights reserved."

It has nothing to do with a single family dwelling.

This is just a "standard" that is not referred to by California Title 24 Part 2.5 or the International Residential Code.

"International Energy Conservation Code*** There are no specific requirements for kitchen exhaust systems in the 2009 or 2012 International Energy Conservation Code."

When the standard you refer to defines a large kitchen as "facilities where total hood exhaust airflow exceeds 5,000 cfm." you should be able to figure out that they are not talking about a residential kitchen.

Obviously you were not being truthful when you said that you got that off your city's building codes website. A govt/city website references the actual code that is signed into law, which I have provided. The code will then, on occasion, reference a standard, but this one doesnt apply to residential.

Click on part 2.5 on this California govt website, under the 2013 edition button, and you will see that it takes you right to the same ICCsafe.org website that you called a bogus source.

http://www.bsc.ca.gov/codes.aspx

I don't appreciate it when someone implies that my intellectual capacity is as low as timmy's and that I would even waste my time posting a source that wasn't relevant, let alone not know the difference.

Seeing how you deleted all the stuff telling me that I didn't know what I was talking about, and that the International Residential Code was not a "reputable source", should I take that as you know you were wrong now, or just that you don't want to leave YOUR rude posts displayed on a public forum?