Outside venting is not option??? Please help...

11 years ago

Am just starting to build (supposed to "break ground" later this week) and my builder just informed me regarding the kitchen (irregardless of what is installed, either microwave OTR or hood), outside venting is not an option. I don't understand how this is possible. Only thing I can think of is it's not included in the baseprice and it would be considered an upgrade?? (which I will go back and clarify with the builder)

Can someone please look at my plans and tell me if outside venting is or is not an option? Please comment if there's any way I can vent my kitchen & the most effective way to do it (to avoid 90 degree turns and the least duct run)? I don't want to not vent to the atmosphere!!

some background in case this is pertinent: house is in NE ohio, two story colonial, kitchen is not on an outer wall; master WIC and full bath are directly above the kitchen, garage is next to the kitchen and an attic is above the garage. Let me know any other info to help the discussion. Thank you.

Here's the kitchen close up (can see it's next to the garage)

Here's the entire first floor (sorry, little blurry)

Here's the entire 2nd floor (attic is above the garage)

Another kitchen close up:

Featured Answer

dazureus

11 years ago

Looks like your beams will run across the page, left and right so if you're using conventional floor joists, will run top and bottom. Is the garage ceiling higher than the interior ceilings? If not, I would think you could run at least a 10" round vent forward through the floor joists above the cabinets then out through the adjoining garage wall and have a remote blower in the attic space above the garage to vent out a roof vent. Another way to do this is to move the stove to the left, and pipe directly out to the garage/attic space with a remote blower. You would lose workspace on the left of the stove though. Worst case scenario is that you have the pipe run through a soffit above the cabinets then out to the garage attic and vent out the roof.

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Comments (11)

kbear_15
Original Author
11 years ago
Are all above options dependent on the garage ceiling height? I'm not sure...what if the garage ceiling is higher than the interior.
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dazureus
11 years ago
I think if the ceiling in the garage is higher than the ceiling on the first floor, it's still possible, but you'll need to box in the vent pipe where it comes through the adjoining wall and you'll need a 90 in there to go up into the garage attic space. Basically it will look uglier, but it still should be possible. Generally the garage floor will be lower than the first floor and the ceiling will be the same height so the roof line matches. Elevations should give you some idea.
kbear_15
Original Author
11 years ago
Thank you for your replies - my understanding is outside venting is a no brainer and really should be done.
nycefarm
11 years ago
My cooktop has a down draft and goes under the floor to the outside. It does have a 90 degree turn...
kbear_15
Original Author
11 years ago
My next few questions would be...

1. does having one 90 degree turn eliminate all usefulness of venting to the atmosphere? (how many 90 degree turns will there have to be to render venting to the atmosphere useless)?

2. What other specific factors would come into play to make venting to the atmosphere useless or have the same effect as not venting at all?

3. If venting to the atmosphere is not an option at all - what are the best "choices"/alternatives? If you can't vent to the atmosphere - I assume there is no advantage of having a hood vs microwave?
dazureus
11 years ago
So it's been a while since I've needed to calculate head pressure losses in pipes, but you have to consider how many CFM your desired vent system is moving before you can calculate how many 90 degree bends will negate. That's why I suggested a remote fan setup since you can get higher CFMS that one that resides in the hood itself.

2. You'll need some kind of port to vent out of and they'll have a spring or gravity baffle to prevent critters from getting back up in. That's some static head pressure too. Piping diameter and type (flex, corrugated, solid) will affect airflow velocities as well. Flex pipes can do angle change sweeps (gradual) for a better flow than solid pipes.

3. You can get a hood microwave too. Even if you can't vent to the outside, a hood can be useful since they have grease traps. Sure you won't be venting heat or smell, but the hood will capture grease particulate and help contain it, rather than having it disperse all over your kitchen.
kbear_15
Original Author
11 years ago
last modified: 11 years ago
Great, helpful comments. Thank you very much.

lets say a hood was 430cfm...then how would you calculate?
dazureus
11 years ago
You might be better off asking this question to the people in the heating and cooling forum. As far as I can remember, it's recommended that you have around 6 cfm per 1000 btu for your cooktop and 430 cfm is probably going use a 8" pipe. Run length and number of bends can be used to calculate if the velocity will drop below optimal for the given cfm.
User
11 years ago
last modified: 11 years ago
Why not run it in a soffit straight across the top of the foyer, laundry and closet? Access to the attic shouldn't be in a closet anyway.

The IRC requires a required attic access to be located in a hallway or other readily accessible location. Even if your building department will allow it in a walk-in closet, you don't want the fire department to waste time searching for it and there should not be anything below it.
kbear_15
Original Author
11 years ago
thank you for more suggestions. JDS - there is access to attic space via the garage as well.