Is 400 Cfm Too Much For A Range Hood For Makeup Air

Hi,

I'm in the midst of a kitchen remodel and have selected and ordered a hood with external blower. Sized per the salesperson'due south recommendation at 1200cfm (900cfm would have been the adjacent size down). Their advice was you can always run the 1200cfm lower just you tin can't turn the 900cfm up. Simply later reading hither and googled posts, I run into that makeup air may be an issue with either one of these loftier cfm beasties. I've been unable to observe skilful info on properly sizing the hood blower itself, let lone means of make upwards air. I live in Austin, TX, rarely does information technology dip below freezing, and nosotros have our summers in the high 90'southward depression 100's for several months, then several more in the 80'south. And so Simply putting a large hole in the wall with a damper will probably murder me on cooling costs. Sure I can open a window when I run it, but nosotros cook at home a lot and it will get mighty hot that mode.

Hood and external blower are Viking (VCWH3648BK)
http://www.vikingrange.com/consumer/...?id=prod180245

and External Blower (DEV1200)
http://www.vikingrange.com/consumer/...id=prod7850176

They are existence installed over a Thermador 36" 5 burner gas cooktop. (SG3365C13) Total BTU output 58,200. Unmarried largest burner 16,000 BTU
http://world wide web.thermador.com/kitchen-app..._SGS365FS.html

I chosen Viking and am told I need a x" duct either way (900 or 1200cfm). The rep wasn't able to help me size the unit. She was quoting some very loose guidelines. They had no suggestions near makeup air.

My vent run will exist straight up from the hood, ninety degrees to get out exterior wall of house (duct volition go up into ceiling and plough to run in betwixt the floors, no attic access at this location).

The existing original exhaust looks to exist a 6" diameter. (Meet photos). I was thinking I might just leave it as is and install a damper which opened in vs. out on the exterior portion to supply a adept portion of the make upwardly air straight behind the frazzle hood (It seems similar from what I read commercial kitchen units often piece of work similarly with the return air beingness ducted to the hood location). The existing duct will not exist removed (as the new ane will just go straight upwards to the ceiling going up through the 2x4 wall as the current one does).

Any thoughts?
Photo 1,3 - Cabinets which volition be removed, existing vent duct here.
Photo 2 - close up of the existing duct, you tin encounter what I believe is a half-dozen" round pipe.

Without make up air, that 1200 CFM exhaust fan, WON"T frazzle 1200 CFM.

Run fan and run into if it creates negative pressure in house. You lot want pressures to exist slightly positive. You should at 900 CFMs have at least a x" or bigger fresh air hood interlocked to exhaust hood and if y'all are in colder climate you lot should put heater element in fresh air. In my expanse annihilation over 300 CFMs you need to interlock to furnace and size co-ordinate.

Don't forget the other appliances that need make-up too. The bathroom fans and apparel drier are exhausting air regularly. In green grass climates, there is the effect of damp exterior air loading your habitation with loftier humidity. I would suggest because a fresh make-upward air wholehouse dehumidifier. The larger units are capable of +400 cfm of brand-up air. Typically, the units are setup to provide 75-100 cfm of fresh when the dwelling is occupied. Upon recieving a betoken from a large exhaust device the dampers can be set-upward to innovate 400 cfm of outside air. During times of high indoor humidity, the dehumidifier removes upto 8 lbs. of moisture per hour. This assists your a/c to maintain <50%RH during moisture cool weather. In addition dealing with the actress moisture from the fan employ, this unit of measurement will maintain <l%RH during moisture absurd weather condition with or without a/c performance. Cheque the Ultra-Aire XT150H thermastor.com. Regards TB

Your 200 CFM fan, probably didn't piece of work well due to lack or make upwardly air.

And this i won't either without it.

Quote Originally Posted past mettius View Post

How would such a device be triggered by the vent hood being activated? What about a variable speed device (such equally the range hood/blower) I'll be using?

Thanks,

A relay powered past your exhaust fan would open the make-upwards air damper and plow on the make-up duct/fan of the dehumidifier. 400 cfm is all there is bachelor, just meliorate than anyother options. More control is very expensive. Regards TB