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Help needed in designing a temperature sensitive exhaust fan

I am trying to design a commercial kitchen with large exhaust fan and hood. My idea is to keep the kitchen temperature sensitive and smoke free. There ned to be two options. One is only temperature sensitive, which means to operate the exhaust fan when the temperature is high. Other is to switch on hte exhaust fan either if the temperature is above a level or there is smoke in the kitchen. Can any one guide me with the circuit diagram for both of these. Note that the exhaust fan motor is a 1/2 Hp motor connected to 230 v AC mains. All feedbacks are sccepted. Thanks

Reply to
pillai.sanjeev
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An ordinary room thermostat will give you temperature control, maybe a smoke alarm for the smoke detection ?

oh just a thought, does it need to detect if the kitchen is hot and smokey due to it being on fire and avoid fanning the flames ?

Colin =^.^=

Reply to
colin

You'll need a differential thermostat, a plain room stat would be no good.

NT

Reply to
meow2222

Even if the room were on fire, I'd think you'd want the exhaust fan going so the room doesn't fill with superheated combustion products and flash over.

Cheers! Rich

Reply to
Rich Grise

It sounds like you want the fan if it's hot, whether it's smoky or not; what if it's smoky but not hot? Do you still want the fan on?

If so, then it's an "or" circuit. Get a thermostat and a smoke detector that have switch closures for output, and put those switches in parallel to control the motor contactor.

Good Luck! Rich

Reply to
Rich Grise

Reply to
pillai.sanjeev

You do not want the fan activated by a smoke detector. If there is a real fire it will pull the smoke out, while pulling more oxygen to the fire.

--
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Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

Apparently, a whole passel of firefighting crews disagree with you:

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It will suck the superheated smoke and gases out, so you don't get a smoke explosion and you reduce the risk of flashover, at least according to these folks.

I'd also think that it would give cooler, fresh air to whoever's trapped in the building, and/or their rescuers.

Thanks! Rich

Reply to
Rich Grise

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