# Kitchen hoods



## plumbdrum (Nov 30, 2013)

just wondering what you plumbers/gas fitters do or are required to do for commercial hood tests? I performed an inspection today the way I've always done and the hood guy told me he's never heard of such a way. I will explain later.


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## bct p&h (Jan 19, 2013)

Are you talking about how the appliances can't light unless the hood is on?


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## plumbdrum (Nov 30, 2013)

bct p&h said:


> Are you talking about how the appliances can't light unless the hood is on?


They can light without hood on with the co detector set up. I'm talking about what do you do for a hood test? What your procedure locally? What does your inspector require?


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## bct p&h (Jan 19, 2013)

Every commercial kitchen I've done since they came out with the co valve has had an interlock for the hood fans. 
They won't light unless the fan is on and the co isn't tripped. 
I am doing a small kitchen remodel where they are reusing the existing hoods and the inspector asked for a letter from an engineer stating the hood is sized correctly for the appliances. Aside from that I've never had an inspector question me about the hood. They might be talking to the engineer or the hood installer and keeping me out of it.


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## plumbdrum (Nov 30, 2013)

bct p&h said:


> Every commercial kitchen I've done since they came out with the co valve has had an interlock for the hood fans. They won't light unless the fan is on and the co isn't tripped. I am doing a small kitchen remodel where they are reusing the existing hoods and the inspector asked for a letter from an engineer stating the hood is sized correctly for the appliances. Aside from that I've never had an inspector question me about the hood. They might be talking to the engineer or the hood installer and keeping me out of it.


 The whole reason they went to the CO detector is so people would not have to always light their pilots. So appliances are lit without the hood on, it trips the co detector, shuts off gas, an audible alarm will sound. It also has to have a Manuel reset. The way your talking about is the old setup with a draft proving switch. As for draft, I make them fill the fryolators and fill pots of water on stoves to make steam to see how the hood is pulling. That's the part that the hood guy never heard of. We have been doing theses tests here for 30 years. I have a rep from the gas co, and fire dept, and the building/ mechanical inspector present to witness the test. I'll have usually the cook if present pull the Abdul, witness the gas shutdown, witness makeup air shut down and fan still pulling. The fire dept witness their alarms and suppression valves with the compressed air. Then I do the CO test to verify everything is working. Then I let everything steam up for about 10-15 minutes to watch the hood, I also check atmospheric gas equipment to see if products of combustion are getting pulled down the chimney due to the hood not being balanced properly. The hood guys can tell me all they want about their design but I've had numerous issues on the first test of something being out of balance. The one I did yesterday the steam was not even making it the exhaust filter, it was rolling right out of the hood. It's a proven way of testing ( at least around here) that really tells how the hood is pulling.


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## bct p&h (Jan 19, 2013)

That's how the electricians wire them around here. 
I've never seen an inspector do that before. The only thing I've seen them test as far as the hood goes is if the co valve trips the gas shuts down and the makeup air shuts down. If that's how they are supposed to be checked you should probably bring that up to the board so they can include it in the next continuing ed for the inspectors.


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## plumbdrum (Nov 30, 2013)

bct p&h said:


> That's how the electricians wire them around here.
> I've never seen an inspector do that before. The only thing I've seen them test as far as the hood goes is if the co valve trips the gas shuts down and the makeup air shuts down. If that's how they are supposed to be checked you should probably bring that up to the board so they can include it in the next continuing ed for the inspectors.




So they have to light the pilots every time they shut the hood down? As far as our procedures, it was put into place about 30 years ago by a inspector in my city that went on to be a state inspector. It's obviously not a code but it's a great way to test.


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## bct p&h (Jan 19, 2013)

I'd say at least 90% of the equipment I put in lately has electronic ignition. The only things I have installed in the past 5 years that weren't were some stoves but those are easy to light from the top and a few tandoors. The tandoors I've seen have been scary. They look like they were built to be wood burning then someone throws a gas burner under it. The burners aren't mounted to anything, they just flop around under it. I don't like doing Indian restaurants anyway, always have a hard time getting paid.


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## plumbdrum (Nov 30, 2013)

We see a lot of pilots down here with fryolators .


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## plumberkc (Jun 23, 2011)

I had a Chinese restaurant that had an oversized kitchen hood that caused the water heater to Backdraft.


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## plumbdrum (Nov 30, 2013)

plumberkc said:


> I had a Chinese restaurant that had an oversized kitchen hood that caused the water heater to Backdraft.



ThAts what I'm talking about, and using my steam method really shows how the hood is acting, either they are drawing to many CFM's or not bringing in enough make up air


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## wyrickmech (Mar 16, 2013)

Everthing we do gets balanced Pryor to any test. Steam would be a good way to se the curtain effect of the makeup air.


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## JimmyMac (Nov 4, 2015)

plumberkc said:


> I had a Chinese restaurant that had an oversized kitchen hood that caused the water heater to Backdraft.


We had a supply motor for a hood go bad and cause the water heater to backdraft out, from a room that was only accessible from an exterior door. Hood sucked so much air you had to have 2 hands on the handle to open the front door to the restaurant!


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