WHEN do you need a make air hood and how would you know if it is any different from a regular hood for an oven?

The county we’re in required us to have a make air hood. I’m not a real technical equipment guy but the only way I can tell is that there are two units on the ceiling (walk-in and freezer units are out back)and a 2nd vent inside the hood.

CAUTION: This post may contain useless information.

it is mo’ betta 2 use a hood w/make-up air…balances a/c/heat etc…believe it will reduce utility cost slightly

“Make Air” is really Make-up air. It is a blower that pushes outside air IN to compensate for the air that your hood is sucking out. Keeps you from having negative pressure.
In my retentive county, I was required to have a full grease hood over my pizza oven, a make-up air unit, and stamped Engineered drawings proving that the make up air was sufficient to compensate for the hood draw.

The main value for the ‘air circuit’ hood as I call it (exhaust and make-up air) is for exhaust of vaporized/aerosolized grease in from cooking appliances. Cooking methods that involve fats will have vapors laden with grease molecules that will afix themselves to anything and everything with the holding power of 2-part epoxy. The hood will tend to draw those vapors through baffles that condense the grease and let the other vapors escape harmlessly out the building. Make-up air provide enough flow to keep the vapors going out of the kitchen without going so fast that the grease condenses in the exhaust ducting creating a fire tunnel.

So, basically any time you fry anything, you gotta have a grease hood according to the National Fire Safety Association, International Fire Safety Association or something like that as adopted at your state or county level. Some counties are even more restrictive (orignorant) and require them in lots of other situations. My county fire marshal doesn’t even know how one works or should be installed . . . but he’ll “come look at it when we’re done”. Rural Georgia can be fun if not fire risky.

exactly. and it’s part of the hood installation process, i.e., hoods aren’t installed without it.

environmental health departments across the country have pretty much taken a lazy approach when it comes to this topic imo - rather than keeping up to speed with every piece of cooking equipment that hits the market, regardless of new technology, it is much easier for them to take the position “if you cook in it or on it, you need a hood”.

but if you feel that your particular piece of cooking equipment does not require a hood (for example, if the manufacturer’s literature shows that it direct vents and/or does not produce excessive heat, grease or vapors) it may very well be worth your time to fight the the hood requirement and seek an exemption - especially given that many counties consider the addition of a mechanical hood a “re-model” which can involve as much headache (building dept. review, ehs review, plan submittals, fees, etc.) as an original construction.

in some states/counties make-up air hoods are NOT required, for instance, in Fla, you can have your deck ovens just using a “heat” hood - no make-up aie…same w/convections…no hood required…

some states require if oven is considered “grease” producing, it may require a grease hood…always check w/regulations

I had to get a makeupair unit for my DINING ROOM as well :evil:
what a bunch of BS, but I was not getting a C of O without it, so it basically sits up in the ceiling unused except when it is a nice day thats is not too hot or cold I might turn it on to circulate the air

I have you beat, I think, on the other side of the spectrum. Our county fire marshall reportedly has no idea what to inspect for hood installation. He is going to come out and look it over when they’re done, but he isn’t so much versed in the fire code for grease hoods. I’ll be t I don’t even have to fork out the $2500 for the fire suppression! I’m gonna for when that one time fire breaks out, though. I know more about the code now than he does as regards restaurants and hoods.

if I have a deck oven is it necessary?

it depends on your state/county regs…a heat hood is a good idea and generally required, but not always…ck w/the local fire department for a quick answer, but not final

Do check your local code. I can do direct venting of the oven and meet code. . . . hard duct 6’ above roof line as the manufacturer recommends.

Only necessary if the city, county, health, or fire inspectors say it’s necessary.

For many years it was common to just put a duct on the flue vent of a deck oven and run it outside. That did nothing to extract the heat but it got the unburned gas out of the shop.

The national building code( BOCCA ) now requires that ovens have a hood to remove grease lade vapors if any, or heat. A class one hood is for grease producing equipment class 2 for no, or very low grease producing.

The code pretty much classifies pizza ovens as a non grease producing unit. that can go under a class two hood and not require a fire protection system. Local jurisdiction should be enforcing BOCCA code as a minimum but some do not. Local jurisdiction may impose more stringent rules than BOCCA that is their option and most are now doing so.

Most jurisdictions now require class one hoods and fire protection for pizza ovens. Especially deck ovens as many ethnic folks roast small pigs, sides of lamb, and lots of other grease producing items in their ovens.
A lot of conveyor oven users do ribs and other grease producing items in their ovens.

With the above and any other hood or devise that exhausts air from a building an equal amount of air must be brought back into the building. That inbound air is to be warmed to within 10 degrees of room temperature that includes air exhausted by rest room ventilators.

There are listed or certified hood that have been tested by Underwriter’s laboratories or a company Known ETL , Equipment testing laboratories. Said certified hood have proven to testers that they can capture and properly exhaust all effluent with a particular hood at a specific amount of exhausted air. Listed hoods can often qualify for up to 1/2 the exhausted air as the same size non listed Hoods. This factor can save a lot of money on make up air requirements.

It is best to size your air conditioning so as to have the make up air supplied by your HVAC system rather than using a make up air system. Reason being that make up air systems have heaters for winter but no cooling for summer. If used a make up air unit is dumping super heated air off your roof into your building,during the summer, defeating the efforts of your air conditioner to cool the building.

George Mills