Range Hood Makeup Air Clarification

[Beercat]

Hello everyone. Apologies if this is a duplicate - I searched and found quite a few topics related to my question, but no definitive answers.

My jurisdiction in Ohio applies the 2018 IRC that requires make-up air for any kitchen range hood over 400CFM. Outside of the open-flame gas range top the hood will directly serve, my home has only direct- or power-vent gas fired appliances (furnace, water heater, two sealed gas fireplaces).

It's difficult to determine per the code if the range itself is considered as a gas-fired appliance that would then require make-up air. It seems like it would be exempt as either (1) not requiring ventilation on its own and/or (2) the appliance being directly served by the hood....?

Thank you very much for your help!

 

[mtlogcabin]

How many BTU's does your stove top put out?

 

[Beercat]

Total output of 6 simultaneous burners is 87,000 BTU. While that condition would rarely happen, I want to size the hood, blower, and ducting to accommodate this. The "divide by 100" rule would suggest a 900CFM hood.

 

[steveray]

OH..........Had a good time in Columbus when we were there for the ICC ABM

 

[klarenbeek]

What IRC 1503.6 requires is makeup air when there is an appliance that is not either direct vent or or uses a mechanical draft system. The intent is to prevent downdrafts caused by negative pressures in the house, drawing product of combustion into the house. I would say that when the hood is running (which is when makeup air may be required) any products of combustion from the stove are mechanically vented through the hood. No makeup air required if all other appliances are either direct vent or mechanical draft.

 

[Beercat]

What IRC 1503.6 requires is makeup air when there is an appliance that is not either direct vent or or uses a mechanical draft system. The intent is to prevent downdrafts caused by negative pressures in the house, drawing product of combustion into the house. I would say that when the hood is running (which is when makeup air may be required) any products of combustion from the stove are mechanically vented through the hood. No makeup air required if all other appliances are either direct vent or mechanical draft.

Thanks for the input - that was my thinking as well. However, I was able to speak with a local inspector, and he disagreed. I may take another run at him, though, because I'm pretty sure this interpretation matches the intent of the code.

I'll post back if I'm able to convince him, or if he offers any other insight. Thanks again.

 

[Gregg Harris]

1503.6 Makeup air required.​

Where one or more gas, liquid or solid fuel-burning appliance that is neither direct-vent nor uses a mechanical draft venting system is located within a dwelling unit’s air barrier, each exhaust system capable of exhausting in excess of 400 cubic feet per minute (0.19 m3/s) shall be mechanically or passively provided with makeup air at a rate approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with not fewer than one damper complying with Section 1503.6.2.
Exceptions:

1. 1.If an exhaust hood system’s manufacturer’s instructions and/or specifications differ from this requirement, the system shall be installed per the manufacturer’s instructions and/or specifications.
2. 2.Makeup air is not required for exhaust systems installed for the exclusive purpose of space cooling and intended to be operated only when windows or other air inlets are open.

1503.6.1 Location.​

Kitchen exhaust makeup air shall be discharged into the same room in which the exhaust system is located or into rooms or duct systems that communicate through one or more permanent openings with the room in which such exhaust system is located. Such permanent openings shall have a net cross-sectional area not less than the required area of the makeup air supply openings.


Make up air would be required in the kitchen area. Mechanical or passive with damper.

 

[Genduct]

What IRC 1503.6 requires is makeup air when there is an appliance that is not either direct vent or or uses a mechanical draft system. The intent is to prevent downdrafts caused by negative pressures in the house, drawing product of combustion into the house. I would say that when the hood is running (which is when makeup air may be required) any products of combustion from the stove are mechanically vented through the hood. No makeup air required if all other appliances are either direct vent or mechanical draft.

I believe the 30% infiltration rate for a Code compliant air sealed home, will more than provide the Makeup and Combustion air needed for a residential gas cooking range
It might be a rule of thumb, but 4 burners were often used as the max for a residential gas stove

 

[klarenbeek]

Make up air would be required in the kitchen area. Mechanical or passive with damper.

I would say in this case makeup air is not required, unless there is a local amendment that changes this section of the 2018 IRC. According to the OP, all other gas appliances in the house are either direct vent or power vented. When the hood is running, the stove itself is also mechanically vented. 1503.6 only requires makeup air if there are any gas appliances the are NOT direct vent or mechanically vented. Some residential hoods can be rated rated for 1000 CFM or more. While providing makeup air for these high CFM hoods is a good idea, its not a code requirement in this case unless the hood manufacturer requires it.