The short (for me, long for you) answer is read as many hood topics on this forum as you can stand to do going back for several years. You may learn a lot about the subject.

The longer, but still way too short answer:

Select a hood with an aperture extending at least 3 inches on each edge larger than the area of the cooktop occupied by hot bases of the pans you might use. You needn't extend at the back if against a wall.

Select a hood that achieves this aperture. Overall size will be larger. Calculate the area in square feet of the aperture of this hood.

Multiply the actual aperture area by 90 cfm/sq. ft. This is the goal flow rate on motor maximum.

Multiply by 1.5 to account for the fan curve -- loss of flow with pressure loss. This is the goal zero static pressure fan rating. This assumes reasonable make-up air availability (another subject that you may have to study from the many messages here on this topic.)

kas

To shorten Kas' comments. Its really a little low on the GE Café. It's TOTALLY inappropriate for the 6 burner jennair rangetop.

Basically you want a capture area as close to 42"x27" for the Jennair or 42"x24" for the GE. You should aim for 600CFM or there abouts for the GE Café. I would recommend 900CFM if you can for the jennair.

Depending on your region, this may also cause issues with Make-Up air. In some locations that code is 300CFM, in others 400CFM. Some have no code. Check with your builder so you don't run into an issue during inspection

Alright guys, thank you so much for your input. I shall bring this up with my builder. I had a feeling that the Broan CFM390 is way too little anyways, I have a Kitchen Aid six burners (40,000 total BTUs) and the hood vent is 600 CFM, and sometimes when I sear, I turned the fan all the way up to the highest setting and I still smell some smoke.

Thanks again :)

I suspect the builder selected that hood to get around the makeup air requirement. I bet you anything it's 400 CFM in your area. Be prepared to pay extra for a makeup air system if you upsize the hood.

Hi Hvtech42:

Sorry I'm lost here. The house that they are building for me is located in Katy, Texas. I have a meeting this Friday with the construction manager, and I would like to ask him about this without sounding stupid. What do you mean by "I bet you anything it's 400 CFM in your area?"

I am planning to upgrade the gas cooktop anyways, so I will also change the vent hood. Do I still have to worry about the Makeup air requirement issue if I upgrade both cooktop and vent hood?

Thanks

hvtech is referring to the requirements for makeup air. Basically depending on your area, the code will specify a maximum CFM that can be used, without allowing for a make up air system (basically a vent into your HVAC system that opens automatically over a certain CFM to replace the air being removed by the hood). When you speak with the construction manager bring up MAKE UP AIR for the hood. If there is a code requirement in your area, he should know about it or be able to find out.

Hi Joe:

Thank you sooooo much for the explanation. That is helpful. I will definitely bring this up in the next meeting. Will update soon. Have a great day!

Hi:

I received a new notification that I received a reply from someone, I can see half of the message on my gmail but cannot find the comment here. Help?

here is the half shot lobobrandon said:Hi Adrian,
As you presumed, your current range hood is not going to get the job done. When picking a range hood, you can go about it two ways - take t...

Their post was deleted.

Agreed that makeup air is not just a code issue, it's a safety issue. For new construction with other gas appliances, you should pretend that it is code in your area, even if it isn't in reality. Still I am guessing it is code in your area based on your builder's selection.

Good Friday everyone :)

I have an update. Talked to the builder and for an upgrade of $2540, I am getting all GE Monogram appliances and the most impt thing that is included is the upgraded 36" Monogram Hood model # ZVC36LSS. This has 640 CFM.

The rangetop will be 36" GE Monogram ZGU364NDPSS. This rangetop has a total BTU of 72,000 BTU ( 18,000 BTUs/burner).

I hope this is a better upgrade in terms of the hood ventilation.

Thank you everyone!

IMHO, the hood does not cover well enough the rangetop you've chosen. Since you'll be doing the deep frying on one of the 4 burners, located on the edges, the hood, both not wide enough and not deep enough, will not be capable of picking up the grease cloud produced. Most of the grease will land on the hood exterior, walls and ceiling. OTOH, the griddle smoke will be captured OK.

The hood is inadequate, and YES, MUA is a national building code that needs to be engineered for in your build for the health and safety of your family. Carbon monoxide poisoning is not a good way to go.

Ok after reading all these, I wonder why the builder even chose this 640 CFM hood if it won't even do the job right? This is so aggravating. I will talk again with the builder. Thanks guys.

That isn't a hood, it's an insert. The hood itself will be custom made. The depth of that insert is fine (and better than many, a lot of them aren't even 20" deep). What matters is the depth of the actual hood.

That insert is fine for the rangetop "by the books" in terms of both size and power, but you could go to 42" width and/or higher CFM for better performance.

ignorance is bliss :) in my previous homes, i didn't even know what hood, how many cfm was installed by the builder, all i knew they were kitchenaids. Now I'm armed with these tips, the builder will think I must be nuts :)