Hello,

First of all, let me apologize if this is an issue that has been talked to death, but I am just now learning about this and my HVAC guy, contractor, and even appliance salesman are ignorant on this topic. Our area is usually behind on things.....

Anyway, we are doing a home reno that includes replacing ALL windows and doors with HE ones and we are doing a kitchen gut and replacement.

In doing so, we purchased a 36" gas rangetop and need to choose our ventilation for this. We are leaning toward a Vent-a-hood liner (hood will be made of cabinetry) that is rated 600 cfm (with 900 cfm effective, according to appliance salesman). After doing research on this, I found the topic of make-up air, which I'd never heard of before.

I consulted my contractor, HVAC guy and appliance guy and they all had very limited knowledge of this, so, basically, I need the low-down on what to tell this so they can plan/construct appropriately.

So, if you you know you're doing, please advise on the following:

1) Parts and ducting needed for Vent-a-hood system
2) Parts and ducting needed for a make-up air
3) How are range venting and make-up air linked together so the damper is opened when vent is turned on?
4) Sizing and spacing on all the above.

Our kitchen has easy access attic space above it (for the time being until drywall is replaced so I've got to hurry on this!)

Other considerations:

*2 gas furnaces (one located in basement and the other located in a crawlspace under a lower level addition
*Replacing current electric water heater to an on-demand one
*Gas fireplace (ventless)

Thanks so much!

If you don't get makeup air from a dedicated intake, it will be drawn through all the air leaks in your home and possibly even backdrafting CO from the furnace and water heater if these are not closed units.

Though I know you're looking for a cheap answer, I'd suggest finding a more educated HVAC designer with commercial experience to be safe.

However, if you don't run the exhaust all out all the time there may be no need for makeup air. We had a 700 cfm unit that was only run full throttle when my spouse cooked fish and offal. I just cracked open a patio door and all was OK.

However, we cook fish a lot since fishing is his favorite hobby. It just surprised me when the reputable appliance dealership where we purchased our appliances said they knew about the need for make-up air but had never sold a single make-up unit.

Thanks!

Good luck!