I have this kitchen island with an old electric downdraft cooktop. I'm wanting to install a ducted range hood. Code requires makeup air if the CFM of the hood exceeds 400 CFM. Trying to determine if 400 CFM would be enough to sear a steak or pan fry burgers on days I don't want to fire up the grill. I intend to replace the cooktop with induction(preferred) or another electric in the near future.

I'm in Texas so a complicated makeup air system is not in the plans. I've considered using the old exhaust duct in the island as the passive makeup air intake. If I have too. That duct goes through the slab to the exterior wall.

Has anybody been through this with success?

Thanks.
-TVz

quote:

Code requires makeup air if the CFM of the hood exceeds 400 CFM

Interesting, first time I'd heard of it, seems a bigger problem with newer homes that are sealed tight with todays building codes to stop a high pressure fan from pulling in bad air, gasses, backdrafting...

Technically that existing path would work, you'd have to install a MUAS fan in it to flow air at the CFM of the hood ie 600 out, 600 in.

Or just put in a 400 CFM hood and see if it works for what you want to do.

Link

I had a 36" Kobe chimney exhaust hood installed over our 30" GE Cafe gas range when we did our gut renovation in 2022 and it does 3 speeds: 300 cfm, 400 cfm and 750 cfm

The highest setting sounds like a 747 on takeoff and we only run that when really doing a lot of things on the stove that might stink/smoke up the kitchen and only for short times. Otherwise it's the 300/400 setting and it's been fine.

I think you will be OK with 400 cfm

We lucked out on our build 7 years ago. Our range hood is between two windows so we just crack open a window when the fan is on.

OK, I'll admit I'd never even conceived of a code for "makeup air" related to vent install. That sucks.

We are finishing up our retirement home and while it's not super-extravagant, one of the things I am most looking forward to is the vent hood over the 48" gas range. It's rated at 1200 cfm, and I'm hoping it will slam doors shut all over the house on high!

Thanks for your responses.

I'm trying to avoid the disappointment of an underpowered hood. As for the noise level I intend to include with the install a "silencer". The Fantech link the HRK provided also has silencers to reduce the noise of higher volume. How good they work - "Don't know".

Georgeair - makeup air would be essential if you go that high. It gets trickier if you crank that up in the winter. Thank could be pretty bad if you have a fireplace going or have other gas appliances running. Like a gas water heater, gas oven or furnace in the basement.

-TVz

My understanding is when interior designers are designing kitchens, the hood needs to exceed the dimensions of the stove by 3' minimum. I cook at a lot so, the more coverage and uptake, the better.

quote:

Originally posted by HRK:

quote:

Code requires makeup air if the CFM of the hood exceeds 400 CFM

eems a bigger problem with newer homes that are sealed tight with todays building codes to stop a high pressure fan from pulling in bad air, gasses, backdrafting...

It's not just newer homes. Mine was built in the 80s and has decent insulation but nothing like the spray in type. When I replaced my furnace we had to have a "Fan in a can" installed to bring in fresh outside air because the furnace couldn't get enough combustion air and was pulling air back in through the chimney.

I assume it would be possible to have something similar happen with a high CFM range hood.

quote:

Originally posted by PASig: ...I think you will be OK with 400 cfm

Re-read your post this morning. Was your range hood up against a wall?

Thanks.
-TVz

quote:

Originally posted by TVzombie:

quote:

Originally posted by PASig: ...I think you will be OK with 400 cfm

Re-read your post this morning. Was your range hood up against a wall?

Thanks.
-TVz

Yes, it goes right out the wall to exhaust to the outside.