# Ansul Hood System Schematic



## dronai (Apr 11, 2011)

I worked on this job a few years back. The control panel was located on the roof. The customer wanted me to disconnect the make-up air, per the inspectors request. 
The point was, some cities, allowed the make-up air to run while exhausting the building, if there was a fire. this inspector said the code changed from the previous restaurants build out.

I was studying this drawing trying to figure out how to disconnect the make up air from switchig on when the Ansel system on the hood went off. See if you can locate the wire.

It's an odd way to draw a diagram in my opinion
The drawing has a large water mark distorting the bottom right.


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## 99cents (Aug 20, 2012)

Sometimes there is a current sensing relay that turns on the MUA when the exhaust fan turns on. If you want to disable MUA in case of fire, maybe trace the wiring back from the NO/NC micro switch in the fire suppression control head.

I don’t know if this helps or hinders...


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## dronai (Apr 11, 2011)

99cents said:


> Sometimes there is a current sensing relay that turns on the MUA when the exhaust fan turns on. If you want to disable MUA in case of fire, maybe trace the wiring back from the NO/NC micro switch in the fire suppression control head.
> 
> I don’t know if this helps or hinders...


That's an interesting way to do it. Nope, this was an old job.


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## CMP (Oct 30, 2019)

It looks to me that your controls are already set up to control the supply air properly, as their shown, if its wired correctly to the drawing.


You might want to check with the Fire Contractor or Fire Marshall for the jobsite. Usually there are other requirements besides just shutting of the supply air. For my area the requirements consists of:
Actuate a strobe horn or two.
Automatically turn on the exhaust fans, regardless of the normal control switch position.
Shut down the intake air supply, air make up unit.
Disconnect the electrical power to all devices under the exhaust hood, except lighting.
Automatically shut off gas supply line, feeding under-hood equipment.
Some require tie in to the alarm system.










The fire control head switch, closed when tripped, should be fed from #4, and the return leg should feed #5. 

When a trip occurs, the fire microswitch energizes CR2-Fire Interlock Relay
CR2 changes states, and energizes starter coils M1 & M2, turning on the exhaust fans automatically.


CR2 also disables the normal input line to M3 (air supply), even though the interlock contacts of M1 or M2 will be closed, when the fire system is tripped.


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## dronai (Apr 11, 2011)

CMP said:


> It looks to me that your controls are already set up to control the supply air properly, as their shown, if its wired correctly to the drawing.
> 
> 
> You might want to check with the Fire Contractor or Fire Marshall for the jobsite. Usually there are other requirements besides just shutting of the supply air. For my area the requirements consists of:
> ...


This is what I was asked to do, but as you point out, it looks like it is already set up to do this. Unless the inspector wanted me to change it to supply air, which seems like a no no with a fire.

Those NC contacts 12&11 energize upon Ansel trigger, and disable the SF (make up air)
Thanks for taking a look


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