Kitchen O/H and range hood and Vent through the floor Conversion

[Cozzmo]

Although, I consider myself handy, I am not not quite up to MMM's high standard of DIY... and am NOT about to do this much work on my own.
BTW, We just retired and moved, so are fixing up the new house.
This project will take 4 skilled people weeks!
So we are totally re-doing our kitchen. A total redesign, The Demo is now completed and they are putting in new flooring and skylights into the ceiling etc.  (Oh and replacing the entire floor for the lower level and stairs).
Yes, Currently, there is no sub-floor and you can see down to the crawlspace!
New Cabinets have been delivered and in the garage.
The appliances are yet to be delivered.

Has anyone done this before? ( To vent an above oven hood downward and out through the floor? )
We bought an overhead hood vent to put in and will be putting in a regular stove.
We are replacing the old downdraft stove.
My wife really loves the idea of having a stainless steel hood over the stove. BUT... the option of venting it through the ceiling is not feasible.
So we intend to utilize the existing vents under the house but still have the illusion of this hood venting out the top.
The downdraft is currently vented directly through the lower cabinet and through the floor and out.
Meaning to vent the pipe out the wall, then down through either the (2x4 wall) OR
(through to the garage on the other side of the wall) then back into the existing pipe that goes through the crawlspace and out.

Would love to have any input.
 
Thanks,
Chris

[lthenderson]

I’m sure you can vent through the floor but probably the reason it isn’t common is because it will be hard to stay in spec with the ducting requirements for your hood motor. With at least two elbows and possibly more, your straight run duct length is going to be really short to be in spec. I would read the ducting requirements for your hood before committing to going under the floor.

[sonofsven]

No, I've never done exactly what you're proposing. Seconding the above,you need to understand the volume required for the hood. Do you know what the size of the existing ducting is?

Since you just bought the house, do you know how well the downdraft worked? I'm usually not that impressed with them, so I wouldn't necessarily want to re-use those ducts.

You say going through the ceiling is not feasible: why? The standard size for a round exhaust duct is 6", either run through the upper cabinet or covered by a finished piece of stainless on top of the hood that is extendable to the ceiling.

Some really powerful exhaust fans require more than a 6" duct, but 6' is enough for most. Once you get into the ceiling, straight up from the hood, is there another level to the house and that's why you can't run it vertically out through the roof? Can you run it to the exterior in the floor joist bay of the second floor and come out the wall?

Another option is to build a soffit below the ceiling that you install the upper cabinets to and run the ducting in there.

The specs for the range hood will have the maximum length of the run, vertically and horizontally, and how many 90* elbows you can use, etc.

Another option is to install an unvented hood for looks and a light and another downdraft range.

[Cozzmo]

Ok, Change in plans...
Very good comments on this, and quite timely as it helped me make my decision even at this late date.

I’m sure you can vent through the floor but probably the reason it isn’t common is because it will be hard to stay in spec with the ducting requirements for your hood motor. With at least two elbows and possibly more, your straight run duct length is going to be really short to be in spec. I would read the ducting requirements for your hood before committing to going under the floor.

Also as sonofsven said...

You say going through the ceiling is not feasible: why?

Point taken.
I had a prior contractor that did not get the job. He recommend the down under thing which seemed like a great idea to my wife and I at the time.
The present contractor likes the idea of going through the ceiling. (After just talking to him)

Now, with the cabinets mostly in already I thought maybe we were at the 'no turning back point'. However after talking with the workers. We are going out the top and through the joists (2x10's) and out the wall.

The reason it seemed hard:
          Is because it has to go over a pantry, and a bathroom and then out through the wall, and my wife and I were really enamored with reusing the existing pipe and saving all that paint and drywall work on the kitchen/bath/pantry ceiling. but I dont' know how bad the ceiling carnage will be until it's in.

The reason it is better:         
          Is because we will only have one bend and a straight pipe all the way.

Anyway, Thank you guys again as there is really no advice out there on this topic.
Thanks,
Chris

[Cozzmo]

Another option is to install an unvented hood for looks and a light and another downdraft range.

Drats, These contractors wanted like $700 extra just to run that thing through the ceiling.
I think that I could do it myself. But with between 3 and 6 contractors in my house at any one time. I just decided to say screw it and take Sonofsven's idea and do the unvented.

[lthenderson]

Another option is to install an unvented hood for looks and a light and another downdraft range.

Drats, These contractors wanted like $700 extra just to run that thing through the ceiling.
I think that I could do it myself. But with between 3 and 6 contractors in my house at any one time. I just decided to say screw it and take Sonofsven's idea and do the unvented.

Having lived for years without a vented (to the outside) stove hood and then getting a powerful one that exhausts through the roof when we remodeled our kitchen, I can say most definitely I will never go back to the unvented days. There are a lot of reasons for that. I prefer gas but couldn't use gas until we had a vented exhaust hood. We love to cook and being able to easily remove heat and moisture to the outside instead of heating up our house interior will probably save the money spent on venting back on cooling bills during the summer months plus just feel less humid. We often cook foods that can fill a house with odor and a good exhaust hood helps prevent that.

But I'm assuming you are also installing another downdraft range so perhaps all those are moot points.

[sonofsven]

Another option is to install an unvented hood for looks and a light and another downdraft range.

Drats, These contractors wanted like $700 extra just to run that thing through the ceiling.
I think that I could do it myself. But with between 3 and 6 contractors in my house at any one time. I just decided to say screw it and take Sonofsven's idea and do the unvented.

I would pay the $700, personally, as I'm not a fan of downdraft ranges vs range hoods, but that's just my opinion.
I believe in spending the money upfront to get the best result, but that's easy for me to say as it's the client's money I'm spending.
Another way to look at it, all those contractors are tearing up your house now, so now is the perfect time to tear it up a little more.

[ChickenStash]

From the description of how it would need to be run, $700 seems reasonable for a pro to do it. If it were me, I'd have the venting installed. It'll never get any easier then when everything is already torn apart and going without venting isn't much fun if there's much cooking being done.

[Cozzmo]

Thank you to all who have replied.
I think that I can always do the top vent if I want to. But, I am just too cheap to part with yet another $700 at this time (and then have to do drywall through my kitchen, then a pantry, and possibly a Bathroom just to get it outside.
Anyway, I did live for a lifetime of unvented stoves. (BTW, My wife refuses to get a downdraft and just likes the look of a hood).
 I guess I'll just have to keep on. Also, I want these guys out of here by thanksgiving.
They have been here everyday working long days for a month now. I like them and all, but, I really just want my house back.
Concurrently, we have been clearing woods, and just recently, we had the crawlspace wrapped and sealed with an expensive dehumidifier system.
Now thinking of replacing either one or both HVAC systems (Two).
and then the 25yo water heaters (two).
A money pit to be sure, But... Yes, It is worth it.
Chris