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How build a cost-effective device that automatically clears exhaust fumes out my garage? Answered

Soon I'm going to move into a building which shares living quarters with a garage. I'd like to rig up some sort of relay-triggering device that opens a nicely sealed set of vents (one intake, one output) and activates a fan exhausting garage air  - one that activates the minute I open the garage door, and then continues exhausting fumes for a few minutes after I drive the car away (and close the garage door). After those couple of minutes, the fan would stop, and the vents seal shut

Due to the "lay of the land" (garage right off a busy road, with very short hidden driveway) I will be backing the car in, so exhaust gases will be concentrated at the back of the garage (close to living areas) - rather than near the open garage door. And as my car has a turbocharger, I often need to let it idle for a minute or two ( to let the turbo cool down) before turning it off to park. So it would be most useful to be expelling those exhaust fumes out of the garage!

The question is - what's really the most simple and cost-effective platform for this kind of a system? Could a 555 timer, a few discrete components and some relays do the job elegantly? Or am I better off just diving into Arduino-Land??

Any related ideas (solenoid-closed vents, efficient fans, ducting through walls, etc ) that are especially thrifty - would also be greatly appreciated!!!


A low knee high wall/partition to separate the garage from the living area will contain the monoxide fumes and keep them from drifting into the living area. It doesn't have to be full length of the garage, just the rear half, say from behind the drivers door backwards.

Then duct through the back wall with a light rubber flap on the outside to seal when the fan isnt blowing, maybe a screen to stop spiders etc.

You have 2 choices for the fan position, either lowdown floor level, or higher up, but with its intake sucking the airspace lowdown on the floor via ducting.

Either way Id use a toilet extractor fan on the inside, keep it out of the weather, and it could be triggered by the garage door with a timed off delay.

Arduino is probably overkill and more expense.

Are you saying that the garage space and the living space are not separated by a wall & door??

Essentially, not! The back of the garage has an open door which leads up a short stairway to the living quarters. And directly adjacent to the garage is doorway to a second garage which I plan to turn into living space. My goal is to keep this building as free from exhaust fumes (and their residue) as is reasonably possible (given my sparse budget...)

The first, and absolutely cheapest first step is to stop letting your car idle. It doesn't need to.

The cooling system is either electric, and runs independently of your ignition (ie, if it needs to, the fan will keep running after the engine stops), or it is a syphonic water system, which circulates cooling water without power from the engine at all. So, you don't need to idle to cool the turbo. In fact, idling prevents the turbo cooling, because heat will be getting transferred from the engine block to the turbo.

Second: fit a curtain to each end of the stair well. This will stop fumes circulating, and keep the house warmer as well.

Third: store all your garage equipment in the adjacent space, behind a locked door. That way you can safely leave your garage door open for a few minutes without passers-by being tempted to pop in and help themselves.

Fourth, when you convert the adjacent space into a living room, do all the above, but install a secure locking chest in the garage for your equipment, and then install a bathroom ventilation fan in the door to the new room, the kind that operates when you switch the light on. It will provide a couple of minutes of air-flow from outdoors to room to garage to outdoors, keeping the room fresh(er).

It is generally reccomended that when a turbo engined car has been driven hard and the turbo operated you idle the engine for a fer mins when stationary to allow cooling oil to circulate round the hot turbo. Otherwise the turbo bearing life will be considerably shortened.

The reason is not the cooling of the turbo, but the oil lubrification of the turbo. When a car run a full boost a turbo can run at 180 000rpm, if you stop your engine after your turbo was pushed, no oil is feeded to the bearing of the turbo, which cause failure of the seal, bearing.

And for the guy who say the fan will keep running if car need to cool.. that's not true and if it would exist, the fan would only cool the radiator which would have no circulation from the water pump from the engine so no cooling at the turbo at all.

PS: and just to the rear of the garage is a very small room I wish to turn into a (tiny) workshop. Don't really want it getting saturated with exhaust particles, either :-)

So, I gather you run your car to keep your workshop warm and you don't want the exhaust NOx and CO ( Carbon Monoxide ).

CO is considered a poison gas because of the way it works on you.

Each inhaled CO molecule grabs a red blood cell and wont let go, this in affect lowers PO2 your breathing volume.

If enough of your red blood cells are tied up as transports of O2 by a CO some of your organs will die and then you will die !

BTW we don't smell carbon-monoxide.

Not planning to run the car in there, no. But I don't want the exhaust particulates building up over time, nor do I want even a minute or two of exhaust fumes finding their way into the living space. So far I'm leaning towards a strategically-placed large funnel on the end of a big tube with a timed exhaust fan... (assuming its feasible to leave something permanently set up near the exhaust pipe)

And I very much appreciate all the ideas so far!

Get one or more bathroom fans. They can be rigged to come on with the bathroom (garage ) light and have a timer built in to run them for a set period.

Carbon Monoxide is heavier then air so to be effective they should be set at floor height.

You can also use trunking to feed the exhaust to where you need it to be.


Uk amazon link.

The density of the carbon monoxide can't be exploited because it comes out hot, and so rises instead of sinks.

It soon sinks again. I worked for Crypton - the car tuning people for a while - Our garage had flexible pipes for putting over running exhausts to vent the fumes outside and 4 bathroom type exhaust fans at the floor level venting to outside. However put the fans at the top and bottom of the wall.

In the UK you would not be allowed to have living space that was directly connected to a garage without an intervening door. In fact a fire door.

You could just run everything from the light circuit, the timer won't work if the power is off. I wonder if you could rig up a tube that you back the exhaust pipe into but that may be too complicated.