Critique my diagram.

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muckusmc said:
HS = Horn Strobe - required here but check with AHJ as to location - some want the HS in the dining area - others in the kitchen.
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I guess in my area, HSs (AVs, as I call them Audio/Visuals), aren't hooked directly to the hood. Instead, a relay would trigger the fire alarm system.
 
That would be true if the struture has a fire alarm system in it - most of the smaller hood jobs (ie: pizza shops and deli's) don't have them - the only fire system is the hood (ansul)
 
muckusmc said:
The inspectors here use a lighter to hold by the sensor to check to see if it is working. Fan comes on with the switch off.
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but why wire it that way to begin with, that means that if there is a fire and the fire alarm detects it the fan won't come on until the sensor reaches 135 degrees, why wait on an emergency situation, not sure I'm ok with it, instead of putting the switch and the sensor after m1 that way if there is a fire it will turn on regardless of temperature and if there is no fire detected but temp goes over the lim the fan will turn on
 
The hood fire system - as per the schematic - is not a automatic fire system - it is only activated by a manual pull station - the schematic is just a basic one can build from.
 
the schematic shows nothing about the fire alarm being manual or not it only shows the microswitches 1 and 2 I hope we are talking about the same schematic.
 
Around here, there is no sensor; the supression micro's activate everything.

hillbilly1 said:
Since there is usually only two micros in the ansul, the fire alarm contractor would love you for stealing his contact.
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That's why I use a single switch whenever I can, and I've come up with some creative ways.

Dinner is calling, but, as Ahnold would say, "A'hl be bahk!"
 
:smile: Critique My Diagram,....Is that anything like,.. "Pimp My Ride"... I think you may have inadvertently created a new electrical Hip hop phrase meaning "give me some advice":smile:
 
dmanda,
Correct - the schematic does not show the mechanical layout of the system - the mechanical system operates the gas valve (non-electrical) via a spring loaded mechanism where the micro switches are located.
 
Okay, I'm back. Dinner was great, thank you. :smile:

muckusmc said:
http://s280.photobucket.com/albums/kk197/muckusmc/?action=view&current=schematic.jpg
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Now there's a diagram I can critique! (Nothing personal, Mr. Muck :smile:)

Why use a contactor for the fans? If they can share a single circuit (i.e., 120v and <20a), the micro's, usually rated at 16a, can handle the current. After all, the micro carries the exhaust-fan's current during system trip in your drawing.

Besides, the micro's will only switch under load when testing or in case of a fire, but not during daily use. Now, if either or both blowers are 240v, 3-phase, or use too much current, then you'll need a contactor or two anyway.

On the other hand, the receptacle(s) and any other electrical appliances should be switched by one or more contactors, and should never be on the same circuit as the system controls and hood lighting; that's a code basic.

I drew up a couple of diagrams while I was eating. The first one basically funtions like the one Muck linked to, but no central contactor and a simpler circuit. The right half is the same as his linked image.

Fire12.jpg

Then, if we really need to use only one micro-switch, as shown in the second drawing, it requires the concession that the fans must be on for the lights and appliances to function. This is required for electric gas valves here, by the way.

Fire13.jpg

Notice that the horn/strobe is connected between the two blowers; the current required is miniscule. A gas-valve and its reset box would be connected across the intake fan (or its contactor) along with the appliance/receptacle contactor(s).
 
In case anyone was wondering about my computer skills for drawing, I made these simple before-and-after drawings (in MSWord), back when I had the time for such luxuries. It shows how to add a single micro-switch to an existing one-switch/two-fan installation.

Before.jpg


After.jpg
 
LarryFine said:
Okay, I'm back. Dinner was great, thank you. :smile:


Now there's a diagram I can critique! (Nothing personal, Mr. Muck :smile:)

Why use a contactor for the fans? If they can share a single circuit (i.e., 120v and <20a), the micro's, usually rated at 16a, can handle the current. After all, the micro carries the exhaust-fan's current during system trip in your drawing.

Besides, the micro's will only switch under load when testing or in case of a fire, but not during daily use. Now, if either or both blowers are 240v, 3-phase, or use too much current, then you'll need a contactor or two anyway.

On the other hand, the receptacle(s) and any other electrical appliances should be switched by one or more contactors, and should never be on the same circuit as the system controls and hood lighting; that's a code basic.

I drew up a couple of diagrams while I was eating. The first one basically funtions like the one Muck linked to, but no central contactor and a simpler circuit. The right half is the same as his linked image.

Fire12.jpg

Then, if we really need to use only one micro-switch, as shown in the second drawing, it requires the concession that the fans must be on for the lights and appliances to function. This is required for electric gas valves here, by the way.

Fire13.jpg

Notice that the horn/strobe is connected between the two blowers; the current required is miniscule. A gas-valve and its reset box would be connected across the intake fan (or its contactor) along with the appliance/receptacle contactor(s).
Click to expand...

on your second diagram, how is power cut off for the intake fan when the alarm is on?
 
Btw

Btw

For those of you who don't know and can hardly spell. :grin:

Critique = a discussion exercising or involving careful judgment or judicious evaluation.
 
dmanda24 said:
on your second diagram, how is power cut off for the intake fan when the alarm is on?
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The SPDT switch directly above the intake fan (or its contactor) is the microswitch. When tripped, it removes the supply to the intake fan, the appliance/receptacle(s), and the light switch.

At the same time, it bypasses the sensor and manual fan switch, since it forms a parallel pathway. That's how I am able to use a single switch most of the time: remove power from one wire and feed it to another.

About the sensors mentioned: when they install systems here, the Ansul head has two cables, one for manual pulls, and the other under tension. There are lead links in the cable above the grease-catchers.
 
Chamuit said:
Critique = a discussion exercising or involving careful judgment or judicious evaluation.
Click to expand...
Are you saying that 'critique' is not a verb? Would you prefer 'criticize'? :smile:
 
LarryFine said:
The SPDT switch directly above the intake fan (or its contactor) is the microswitch. When tripped, it removes the supply to the intake fan, the appliance/receptacle(s), and the light switch.

At the same time, it bypasses the sensor and manual fan switch, since it forms a parallel pathway. That's how I am able to use a single switch most of the time: remove power from one wire and feed it to another.

About the sensors mentioned: when they install systems here, the Ansul head has two cables, one for manual pulls, and the other under tension. There are lead links in the cable above the grease-catchers.
Click to expand...

but the strobe is connected to the intake fan so you are suplying power to the intake fan through the strobe. no?
 
dmanda24 said:
but the strobe is connected to the intake fan so you are suplying power to the intake fan through the strobe. no?
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No. Since the strobe requires so little current, I'm supplying power to the strobe through the intake motor.

There's nothing that says one side of the strobe requires a directly-grounded conductor; it just needs 120v.

It's the only place there's a potential only during an alarm condition in the single-micro-switch diagram.
 
LarryFine said:
No. Since the strobe requires so little current, I'm supplying power to the strobe through the intake motor.

There's nothing that says one side of the strobe requires a directly-grounded conductor; it just needs 120v.

It's the only place there's a potential only during an alarm condition in the single-micro-switch diagram.
Click to expand...

so there is current going trough the intake fan just not enough to make it move? how about the contactor coil, it is also connected in series with the strobe, would it be enough current to energize the coil?
 
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