Return to the Appliances Forum | Post a Follow-Up

 o
Adequate ventilation?

Posted by dalf18 (My Page) on
Tue, Aug 13, 13 at 21:57

We are installing (as part of our kitchen reno) a new DCS gas cooktop, 4 burners: 1-15,000 BTU, 2-11,000 BTU, 1-10,000 BTU. Our KD thinks we need a 36", 1000 CFM hood. The appliance stores seem to all think a 30", 600 CFM hood is more than adequate.

We have a small kitchen (about 10' x 11') which will be open to the dining room after the reno. I think a 36" hood may overwhelm the kitchen.

We are looking at a Zephyr-made 30", 600CFM hood with baffle filters and a 7" duct opening sold under the store brand at Yale Appliance in Dorchester. We're not yet sure if it will vent through the wall and then up to the roof or directly up through the roof.

We don't know who to believe. I have read a lot on this site and other places and still don't know what to do. Thanks for any help!!


Follow-Up Postings:

 o
RE: Adequate ventilation?

600 cfm is adequate.

A 1000 cfm blower will be quieter running at 600 cfm than a 600 cfm blower running at full crank. With the rare exception of an ultra premium 600 cfm blower and very low quality 1000cfm blower. But comparing blowers in general and particularly within the same brand this is true.

Many people put 30" rangehoods over 30" cooktops. Then again many people don't have rangehoods because they feel they don't need them or because they think they look ugly.

You could definitely use the extra capture of 36". And depth is more important than width. You really want a hood that is at least 24" deep. Those 18"-20 1/2" deep hoods only adequately vent the rear burners. Ideally you want a 27" deep hood but not overwhelming a small kitchen with a 27" deep hood is a valid concern.

I have smallish galley kitchen with a 42" x 24" SS hood over a 36" range. It is a very shiny 304 SS that reflects light really well . If it was dull or a dark color it may suck the light out of the kitchen and look oppressive. So I like my hood quite a bit.


 o
RE: Adequate ventilation?

I have a 30" DCS range with 4 16K burners and 1 17.5K burner and have a 600 CFM hood over it and it is fine - I rarely ever run it on high - mostly on low and occasionally on medium. It is 30" wide but I have flanking cabinets which never get covered with grease so I don't think 36" would make a difference unless you don't have flanking cabinets. I do agree with deeageaux that you want a deep hood - mine is only 19" deep and I do get some grease on the outer front of the hood.

One thing to be concerned about is make-up air - many locales don't require make-up air for hoods 600 CFM and under but some places now, particularly in cold climates require make-up air for hoods over 400 CFM. Check you local building codes. 1000 CFM would require make-up air and is overkill for your cooktop.


 o
RE: Adequate ventilation?

Thank you for the responses!

The 30" Zephyr-made hood I mentioned above is 22 1/2" deep, 7" duct. I've identified two others which are deeper:

Broan Elite E60000 series E6030SS - 24" deep

Faber Maestrale MAE30SS - 25" deep, duct 6" round

I've included the duct measurement when available as I've read this has an impact. The Faber is deeper but with a smaller duct and I'm not sure which is more important.

Does anyone know anything about the above two products?

Thanks so much!!!


 o
RE: Adequate ventilation?

The Broan has optional 7",8", or 10" duct options.

And it has an MUA code compliant unit that can be purchased as an accessory.

If you have local MUA regulations this can be critical.

Hopefully our resident engineer/venting specials Kas will chime in.

His answers can be long winded but hopefully he gives a clear yeah on of the options.

If he does not answer in the next 24 hrs you can make a shout out thread with "Kas" in the title.

Here is a link that might be useful: E6030SS Data


 o
RE: Adequate ventilation?

Thanks again for your help.

Since I'm installing a cooktop, the burners will be closer to the wall than if I were installing a range. Do you think that my hood would not need to be as deep?


 o
RE: Adequate ventilation?

dalf, I don't believe that the hood has to be as deep as 27" - keep in mind that if it sticks too far out, you'll either have to mount it higher (which will make it less effective), or you'll constantly bump your head on it. I have a hood that's 21" deep, it works fine, and it's never gotten in the way or resulted in a forehead bruise.

IMHO, a shallower hood installed lower, is going to be as effective as, or maybe even more effective than a deeper hood installed higher. The higher the hood, the more the smoke is going to spread out before it gets to the hood. Mine is at 27" above the cooktop, and I hardly ever use it above the 2nd speed, which is really quiet.


 o
RE: Adequate ventilation?

If it's an island hood as opposed to a wall one, it will need to be both more powerful and larger.


 o
RE: Adequate ventilation?

Sorry I left that out - it is a wall hood.


 o
RE: Adequate ventilation?

deeageaux: Long winded is the best ventilation. :)

However, I'm not sure what the question is. I can't comment on particular brands that I don't own or haven't owned. I have written a lot on the desirability for hood overlap of pan surfaces, flow rate sufficient for the hood aperture, and aspects of MUA design. Maybe a narrowly tailored question will focus my attention.

Reviewing the literature referenced in my My Clippings may also be helpful.

kas


 o
RE: Adequate ventilation?

Kas,

Which will vent better?

The 25" deep hood with a 6" duct or the 24" deep hood with a larger duct.


 o
RE: Adequate ventilation?

dalf, I don't believe that the hood has to be as deep as 27" - keep in mind that if it sticks too far out, you'll either have to mount it higher (which will make it less effective), or you'll constantly bump your head on it. I have a hood that's 21" deep, it works fine, and it's never gotten in the way or resulted in a forehead bruise.

No one here claimed that the hood has to be 27" deep.

You may think that your 21" deep hood works fine but a 24'-25" deep hood will work better.

And no one is hitting their forehead on a 24-25" deep hood either since no one needs to have their head over the pan to cook or see the contents inside. Plus the fact that it would be uncomfortable.


 o
RE: Adequate ventilation?

A 25-inch hood will capture slightly better than an otherwise equal 24-inch hood due to greater overlap, but it might not contain the effluent (keep it and remove it) if the flow rate is too low.

A six-inch duct will have more flow resistance than an equally long larger duct. For equal fans the flow rate will be lower with the six-inch duct and there is more risk of containment failure. (Although without more data we don't know if there is containment failure in both cases.)

If the fans are not equal, then one has to look at the fan curves to figure out what will happen, taking into account the pressure drop across the baffles (a guess usually) and the pressure drop in the house due to imperfect make-up air supply (another guess unless the MUA is being designed with the ventilation).

Given general equality of parts, with only the duct diameter changing inversely with the hood front to back depth, and given that 24 inches is probably good enough for capture with a wall mount, I would go with the 24-inch and a larger duct; but in reality I'd analyze both cases before making a decision.

kas


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Appliances Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here