Hi...

I need to know what kind of smoke sensors (to use with AtMega328PU or Arduino) I should buy to detect smokes coming out of a fireplace! I mean, what is a suitable smoke detector to detect smoke of burning firewood??? There are several gases detectors but I'm not sure of a specific one for firewood smoke!

ThanksPsy

 

For best coverage you need both photo (optical) and ionization detectors. If you look at the test results, they really do perform well at one type of fire or the other, but not both, so you need both sensor types. IMHO, don't risk inventing one yourself, get an off-the-shelf proven design for something so important.

From this article on Consumer Reports: http://www.consumerreports.org/cro/co-and-smoke-alarms/buying-guide.htm

Ionization Smoke Alarms are best at detecting the small particles typical of fast, flaming fires but in our tests, all tested poorly for detecting smoky, smoldering fires. Ionization units are prone to false alarms from burnt food and steam, so don't mount them near a kitchen or bathroom.

Photoelectric Smoke Alarms are best at detecting the large particles typical of smoky, smoldering fires but poor at detecting fast, flaming fires. Photoelectric units are less prone to false alarms from burnt food and steam, so you can install them safely around the kitchen or bathroom.

Dual-sensor Smoke Alarms combine ionization and photoelectric technology to save you the hassle of installing two separate smoke detectors. But you will still need to install CO units.

 

I would go with a Dual sensor type, for fast fires and slow smoldering ones...

http://www.asecurelife.com/best-smoke-detector/

 

Ok guys, thanks for the thorough and fast replies. Probably I should have given a few more details about what I want to do. This is for a home simple project to try to avoid smoke getting out of the fireplace and "flood" the living room. It's not intended to detect and prevent any type of fires.
So, this said, do you guys maintain your suggestions or does this latest details changes the whole picture?

 

Smoke detectors Detect, they don't stop fires or smoke, proper ventilation of your fire place will stop that.

 

Smoke detectors Detect, they don't stop fires or smoke, proper ventilation of your fire place will stop that.

Well, that is my home small project. To build the complete system. Detection and ventilation.

 

An IR LED and phototransistor at 90-degrees to each other. Once smoke is present, the IR reflects off of the particles and can be "seen" by the phototransistor.

You'll need to do some experimentation but this was a simple example used in an old op amp book. The concept works and works better with a comparitor than an op amp. Good luck with your project.

 

Well, that is my home small project. To build the complete system. Detection and ventilation.

But realize that when the amount of smoke is present in the room to detect, it's already there. Building both the fire and the fireplace need to be done correctly, to work efficiently. My house has a fireplace that let smoke out when first started, until I found the secret. That is to "preheat" the flue. A column of cold air in the flue acts like a "stopper" until it gets heated. Just rolling up a section of newspaper and lighting it on fire and holding it in the flue opening before actually starting the fire works very well, at least in my situation.

 

My goal was to take a small pipe, make a couple of holes, place it at the front of the fireplace at the top of it, take an air pump and make it blow to the pipe when smoke is detected.
In my case if there is some wind in the outside, I get smoke in my living room a lot of times because the outside wind pushes the fireplace smoke into the living room.

 

You could hack an off-the-shelf dual sensor detector. Battery operated or hard wired, they're not expensive. You can use the siren power leads as the trigger for your circuit:

https://www.amazon.com/gp/product/B00PC5THCU/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B00O8MVW44/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

Hum, ok and is that suitable to stand close to high temperatures? I need to place them the closest possible to the fireplace entrance. There will be some temperature there. I'll draw a schematic of what I have in mind.

 

My goal was to take a small pipe, make a couple of holes, place it at the front of the fireplace at the top of it, take an air pump and make it blow to the pipe when smoke is detected.
In my case if there is some wind in the outside, I get smoke in my living room a lot of times because the outside wind pushes the fireplace smoke into the living room.

Well if that's the case, the fix is pretty easy. https://www.google.com/search?q=chimney+cap&ie=utf-8&oe=utf-8 Take your pick from them. Or if a DIYer make your own. Is the chimney above all other roof lines? This is also a problem sometimes. Wind does some pretty unusual things(at least from a humans viewpoint, not the physics viewpoint)

 

Well if that's the case, the fix is pretty easy. https://www.google.com/search?q=chimney+cap&ie=utf-8&oe=utf-8 Take your pick from them. Or if a DIYer make your own. Is the chimney above all other roof lines? This is also a problem sometimes. Wind does some pretty unusual things(at least from a humans viewpoint, not the physics viewpoint)

I'm not sure if that avoids the outside wind to push the fireplace smoke into the living room, but I wanted to try my idea unless it is really complex or tricky!!

 

I'm not sure if that avoids the outside wind to push the fireplace smoke into the living room, but I wanted to try my idea unless it is really complex or tricky!!

To try it just get a computer or desk fan and see if it works. No electronics involved. But still say if the smoke is in the room, it's already too late.

As to chimney caps working, here's a good link - http://www.woodheat.org/wind-chimney.html

 

To try it just get a computer or desk fan and see if it works. No electronics involved. But still say if the smoke is in the room, it's already too late.

As to chimney caps working, here's a good link - http://www.woodheat.org/wind-chimney.html

I'm not saying that the smoke is already in the living room. The detectors would be to detect when the smoke is pushed out of the fireplace and at that moment, the window blowers would blow small bursts of wind to keep the smoke inside the fireplace. That way, at least, most of the smoke would get into the living room.
It would work like those devices that are placed on top of bar's/cafe's doors to keep the cold temperature outside. I'm not sure how they are called in English but a raw translation would be something like wind cutter.