Exhaust hood question

I have looking at a B&M place recently that is on the lobby level on a multi-rise. Behind the space is more lobby, to the sides are other tenants, and above of course is more floors.  It seems the only option I would have is to put the exhaust fan in front of the space which is the only true exterior part of the space.
 
The kitchen is situated in the back of the space, and I would have to run the duct work a good 35 feet to make it to the front exterior wall. My question is:  does anyone know how far your exhaust fan can be away from the actual hood itself?  I know 35' is going to make a big difference in the amount of up-flow. But just wondering if it's doable?  It currently has a tiny 20" self contained all-in-one exhaust/fire suppression deal that I guess uses charcoal for filtering the air, with no exterior venting required. He's got 2 burners, and a 6"x18" griddle underneath it. And that's just not going to cut it. 
 
Any advice is appreciated.

Air movement thru the duct is no the problem. You would only need a slighty larger fan.  .... The real problem is moisture (condensation) & grease build up in the duct.  The grease could be a fire hazard.   ... You need to check your local codes (HD, HVAC, & Fire) if allowed get professional design help for the duct.
 
The duct needs to be very accessible for inspection and cleaning.  ... It also needs to slope to a collection point and to keep moisture from draining/dripping at the hood.

I'm not sure the distance from the roof to the grill is all that important, they will just have to adjust the powder of the fan system. All hood systems should be on a 6 month cleaning schedule. The inside hood and filters should be on a cleaning schedule depending on how busy the restaurant/food service is..............

As a sprinkler fitter it will probably need fire sprinklers also

Billy, ... AZ stated he is looking to locate in a multi-rise.   Venting to the roof is not likely.  He indicated running the duct above the ceiling to the front exterior wall, about 35 ft.  ... 1st, it would be questionable if the Owner would even allow a greasy kitchen fan on the front of the building; ... with grease running down the wall.  With a long horizontal duct run, grease & moisture will condensate in the duct; ... extra attention will be require to regularly clean the duct, in addition to normal cleaning of the hood & fans.  

KurtSara


As a sprinkler fitter it will probably need fire sprinklers also

 
More likely a halon alternative system; ... FM200 or CO2   ... The last thing you would want is burning grease to be washed out and spread all every thing.

Hi Ed, your right I miss read the post, I don't think there is any way to go horizontal and have it pass...................

Doing a quick search, I think the solution will be auto-cleaning equipment like this.   Then the clean air could then be exhausted to the building exhaust system.
ref:http://www.breathepureair.com/kitchen_exhaust_hoods.html
http://www.breathepureair.com/aqe_kes.html

 
Note: The indoor system is mounted between ceiling joist above the kitchen hood.
 
Now, I hope this helps. .....

BillyB


Hi Ed, your right I miss read the post, I don't think there is any way to go horizontal and have it pass...................

Oh, ... there is always a way!  ... It just depends on how much an owner is will to pay an Engineer to figure it out and to meet codes.   .... no charge of the above ....

If I read that web page about the auto-cleaning system correct - there still needs to be an exhaust extraction fan installed?
 
Or, can that unit tie directly into the existing HVAC exhaust duct work?  If it can tie directly in, then I suppose that the unit has enough up flow to suck-up the smoke/fumes etc? Because I know the HVAC intake doesn't have that kind of suction. 
 
The unit space already has a halon central sprinkler system installed, as well as throughout the 10 floors of the building.
 
P.S. I see in their leasing program that it mentions that $100k can be wrote off.... I surely hope that their system doesn't cost $100,000.
 
Edit - I see from this link here that it's stating that the CFM is 2000 - would this mean there is a exhaust fan self-contained within it?

1: ... An exhaust fan is required. It is still a part of the basic hood system.
2: ... You can not tie into the AC system. The hood exhaust needs to vent to the outside.  The building should have vent/exhaust system or a vented equipment chase that could be used.  This would have to be investigated.   ... Another possibility, is to reused the clean air as part of the required make-up air to the kitchen, ... but think the air maybe too hot to economically cool & reuse.
3: ... The duct between the hood & auto-clean unit would still be required to be in a fire-rated chase.  If a fire suppression system is required in the chase, this would be separate from the build system.   You don't want a small fire here to trigger the building system, ...if it can be quickly put out, ... much the same as the fire system over your cooking line.
4: ... I don't think these units cost 100 grand.  ... I only link to that web page as there was clear diagrams and instructions as to what needed to be done.  ... Shop the equipment & get professional engineering help. ... The manufactures may be able to help you with the design.
5: ... Kitchen hoods are required to exhaust air at a rate of 200 to 550 cfm per foot length of hood or Code requirement, depending if your kitchen equipment is heavy, medium or light duty appliances. ... Most likely you would be in the 400 to 550 cfm per foot exhaust range.    ... Look at this design guide and note the energy cost for a standard 20ft hood vs. an optimized & engineered 20ft hood at the end.  ... Air out must be replaced with air in.  This can take 10 to 15 tons of additional AC just for your needs.   ... An Engineer here can save you money with proper equipment and yearly operating cost. ... You are looking at a substantial investment for a Hood system & make-up air system, so a long term commitment to the location is required for it to payoff.  http://premiumair.net/ckv%20design.pdf
 
** Your original question of using about 35 ft of duct to the front of the building:  ... Codes will require the duct to be liquid tight (18ga metal & welded joints ??) and installed inside a fire-rated chase.  ... In addition, clean-outs must be installed every 20ft. and the duct sloped back to the hood or slope to a grease collection point.  ... You still have a problem of getting the owner's permission to install an exhaust fan on the front of the building (I don't think this will happen ??). ... And you still have to install a make-up air system (with HVAC ???).

Well it looks like I will have to take out their little griddle and 2 burners, and put a 24" electric griddle in there - this is what they have now.  (see pic)
 
Underneath this small hood they have a 3 prong ansul system - not sure how well this little hood is going to deal with the smell and smoke of cooking burgers.  But I guess it did OK, because no horrid smells when I walked into the kitchen.
 

 
And then for the fryer, I will either go with a used ventless fryer, or buy a self contained exhaustless hood for the fryer for about 3k - 4k.   I think that it will be cheaper than any of the other alternatives of trying to run a full hood system in there, which I am guessing is going to be around 30k+ if I can even get it all worked out.
 
The thing that is going to majorly suck is that going this way is going to severely limit my production capacity.  During lunch, I need to put about about 60+ burgers in a 2 hour period.  Sometimes I get 1 person coming in and ordering for the whole office (5 or 6 people) and I need to slap them down at the same time. 
 
I have a roundup toaster for the buns, but I will still have trouble when someone wants bacon, sauteed mushrooms etc.
 
So aggravating!

I think the best way to do this is just trust it to the experts, their are a lot of expert people on hood installations like this website:

Not sure about your local codes but that hood is not big enough for the cooking space. Most HDs and fire marshalls want the hood 6" bigger around than your cooking area. I would seek pro system design help for sure.

This is an old thread   ... the hood pictured is a vent-less vapor & greases hood.   The hot air is blown back into the kitchen and at the cook.   See the exhaust vent at the top of the hood.       For a start up and this kitchen situation, this may be the most practical solution until cooking volume & number of customers severed can justify the expense of professional design & high volume equipment.