# CO sensor fan control



## chris kennedy (Aug 14, 2016)

I'm looking at a set of plans for a 4 story dwelling on Fort Lauderdale beach. The ground level is of flood/breakaway construction. (Not inhabitable) There will be enclosed vehicle parking  on this level.

Plans show exhaust fans controlled by CO sensors in this area. Nowhere on the MEP pages is there a spec/detail for said sensors.

1) What level of CO should trigger the fans?
2) Do these need to trigger the CO/Smoke alarms throughout the dwelling?

Thanks


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## cda (Aug 14, 2016)

Florida code say anything??

As in is this extra??


Only required within ten feet of bedroom and not interconnected??


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## chris kennedy (Aug 14, 2016)

This is unique.


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## cda (Aug 14, 2016)

Had them in one fire station, and they were removed for unkown reason?


I am thinking as long as they meet base minimum requirements,,

Anything extra is gravy


Does not appear the minimum have to be interconnceted???


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## Msradell (Aug 14, 2016)

When I've seen installations like this in the past (one was in a firehouse like cda mentioned) they were standalone and only turned on the fan(s). The facilities also had additional CO alarms in the habitable areas that were completely separate.


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## mtlogcabin (Aug 15, 2016)

2012 IMC
404.1 Enclosed parking garages.
Mechanical ventilation systems for enclosed parking garages shall be permitted to operate intermittently in accordance with Item 1, Item 2 or both.

1.    The system shall be arranged to operate automatically upon detection of vehicle operation or the presence of occupants by approved automatic detection devices.

2.    The system shall be arranged to operate automatically by means of carbon monoxide detectors applied in conjunction with nitrogen dioxide detectors. Such detectors shall be installed in accordance with their manufacturers’ recommendations.

The purpose of the detectors is to operate the exhaust system when the CO levels reach a certain level. The code does not define a minimum PPM to be met by the detector.

I would ask if occupancy sensors would be an acceptable method in lieu of the CO detectors. Right on the beach I could envision the salt air corroding/coating the sensors in a short time making them useless.


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## Builder Bob (Aug 15, 2016)

Co Sensors are a high maintenance issue unto their selves - 5 year shelf life ( home sensors) and commercial applications may require re calibration on a 6 month to year rotation dependent upon which environment you are operating in.

Not a big fan of being reliant on mechanical means to start exhaust when levels are reached that are to high

Also, what are the design parameters for the sensor and monitoring devices - is it based on OSHA Time waited average or is it based on IDHL levels or both.

I see potentials for false start ups if you drive into and out of the enclosed garage a number of times during the day - Saturday for example, golf, grocery shopping, kids at parks, games, dining, etc.

Although the levels may never reach the IDHL levels, it may exceed the TWA and perform a start up....


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## tmurray (Aug 16, 2016)

Builder Bob said:


> Co Sensors are a high maintenance issue unto their selves - 5 year shelf life ( home sensors) and commercial applications may require re calibration on a 6 month to year rotation dependent upon which environment you are operating in.
> 
> Not a big fan of being reliant on mechanical means to start exhaust when levels are reached that are to high
> 
> ...



We just installed some in our works garage. They were expensive. Maintenance is expensive. They are worth every nickel (we got rid of our pennies a couple years ago). Basically, the manufacturer stated the density for the floor area and indicated the sensitivity. We have ours set to run after they detect CO for a sufficiently long time to prevent unnecessary cycling of the equipment.

As someone who took HVAC in college, I'm not a big fan of relying on occupant interaction to run mechanicals. As one of the instructors said "machines don't forget to turn on" The only time that there can be a problem is when they are not maintained properly, which is still human error.


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