Mechanical Q: What makeup air requirements are associated with vented kitchen range hoods? (IRC M1503.4, M1501.2, G2447.6)  Three code provisions can trigger the needful makeup air in this situation.The bottom line is that makeup air is always required for high-volume hoods (> 400 cfm) and may be required for lower volume hoods when natural-draft appliances are used.  M1503.4 requires makeup air for kitchen hoods which exhaust more than 400 cfm. The makeup airflow rate must equal the exhaust flow rate and an intake damper on the makeup air duct must be interlocked with the control for the fan.  M1501.2requires that“ducted exhaust systems”(such as kitchen hoods,bath fans, clothes dryers) not induce negative pressure in excess of negative 3 Pascals at the location of a natural- draft combustion appliance. This provision applies regardless of the rated airflow of the exhaust system.  G2447.6 reinforces M1501.2, more explicitly for vented kitchen hoods. This provision is independent of the rated airflow through the hood.  A pressure test is required to demonstrate that the depressurization level is within the 3Pascal limit. If the depressurization limit is exceeded, makeup air is one potential solution.  There is no requirement to temper makeup air.

At the moment, I would call them concerns pending further information. First, do you have any combustion appliances connected, air wise, to the kitchen? Combustion appliances include furnaces, hot water heaters, and dryers. If they all have their own make-up air sources, then they don't count. Fireplaces count unless roaring hot and quite large, in which case they need their own make-up air even without any kitchen ventilation effects. One of two windows cracked open a couple of inches will perhaps achieve adequate make-up air for a quite low CFM requirement in lieu of wall cracks and other dusty paths. Bathroom exhausts and dryer vents should have dampers that will not allow enough MUA for any purpose. Gas fireplaces are required to not have dampers, so only the doors limit back-drafting. That is also an undesirable path. 300 CFM, for example, is 5 cubit feet of air per second. This would require more than a couple of inches of window, even if unscreened, to avoid an undesirable pressure drop in the house when combustion appliances are present. It will certainly degrade the flow rates of the kitchen ventilation blowers, more so with VaH squirrel cage blowers used in Magic Lung systems. What are the claimed CFM of the VaH inserts you are using? (Zero static pressure values not Magic Lung claimed equivalent values) What is the area (or dimensions) of the air intake aperture at the bottom of the hood assembly containing the inserts? Is there some overhang of the overall hood relative to the entry apertures of the inserts?

I need a 30" wide range hood insert, or whatever 28-29" that will fit in a 30" space. Ideally it would be wider, but that isn't possible in my kitchen. I'm looking at 18-22" deep. Preferably without any electronics to burn out. I don't have the budget to go with anything insane. I'm looking to spend ideally $1000 maximum. Quiet is a big bonus so the wife doesn't complain about it. I'm coming from a non-venting OTR microwave, so anything would be an improvement. Range with be a 30" wide induction cooktop. Every single company that I look at seems to get terrible reviews. I've spent days on this and am beyond overwhelmed. I just need to order something. Does anyone have any suggestions?

I hate wood hoods they get greasy and discolor from both grease and steam so can't help.But I guees if you do not use the range it won't matter.As for the insert you need to now go to a place tha sells inserts with your meaurements of the hood you have already ordered which BTW should have been oredered after you got the hood insert.