Furnace

skoni

I would like to automatic start the extractor hood as soon as I turn on the gas from the furnace.

Now I have been searching for the right flow swith to measure that. bit can't find a good (pricebly) one.

The idea is to start the extractor as soon as one of the gas burners is started.
So I need to measure a gas flow. 

Maybe any ideas ?

iTSMe

Measure the temperature above the furnace and use that as trigger.

skoni

I am afraid that if the gas in on a low setting there will be not enough temp. raise to trigger.

Eternity

Burnt gas results in H2O and CO2, both could be measured and perhaps used to create an ON trigger. Off might be more tricky... 

Eternity

Or perhaps you light the gas with a built in ignition? That use of electricity could me measured and trigger the hood.... But off is a problem. 

skoni

Eternity said:

Or perhaps you light the gas with a built in ignition? That use of electricity could me measured and trigger the hood.... But off is a problem. 

Tried that. Current is to low..no amps show up in the coolcam

Eternity

Or...a motion sensor in the hood, aimed at the burners. The hood starts when motion is detected, being it a pan placed or a hand waved. Combined with a countdown timer to keep the hood active. And perhaps an extra motion sensor in the kitchen that also retriggers the timer

skoni

A motion sensor will not cover the situation. When there is no motion it will turn off the hood. 
Oke you can put in a delay but it isn't the sollution i was hoping for.
Maybe it is a project that's not that easy.

JPe

https://www.indiegogo.com/products/oval-the-first-all-in-one-smart-sensor-system

skoni

Nice, but expensive. 

JacobCasey

Yes, it can be done but a little expensive. Maybe it will be good to consult a professional heating service NJ for an advice. They are the one with the correct knowledge and may tell the most convenient way to measure it.