Gas furnace in garage/shop sucking up bad air?

Chang

Chang

Joined
Oct 9, 1998
Messages
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Does anyone else here have a gas furnace in their garage and also do knifemaking in their garage? I'm not sure exactly how these gas furnaces work (mine is a Trane gas furnace), and I'm afraid the furnace might suck bad air from the garage and send it into the house. Anyone know if this should be of concern?
 
Any combustion will generate some amount of carbon dioxide and carbon monoxide.
Both gases are dangerous, in a different way.
You can't live breathing carbon dioxide: it doesn't give any oxygen to your blood and you would suffocate.
Luckily, being carbon dioxide one of the major byproducts of our body, our body itself is really good at detecting it, and any significant amount of carbon dioxide will give you a sensation of suffocation.
Carbon dioxide is'n poisonous, it just doesn't give your body anything it can use to live and if saturates the air you won't get oxygen and die. But, as said, special sensors in our windpipe make we immediately alert of the fact that the air we are breathing is lacking oxygen.

Carbon MONOxide is another thing entirely.
First and foremost, it's a lethal poison for our body. Each carbon monoxide molecule binds permanently to a molecule of hemoglobine rendering it useless for its purpose: carrying oxygen to the body.

Moreover, carbon monoxide is extremely insidious: it doesn't smell, it's invisible and our body lacks any sort of sensors for detecting it.
Carbon monoxide is LETHAL. Once you are poisoned with it, there's NOTHING that can be done. Oxygen therapy has only marginal effects, because it just gives more oxygen to the remaining, sane hemoglobine, to carry, to make up for the blocked hemoglobine.
But if too much hemoglobine has been destroyed, even breathing pure oxygen won't save you, as nothing of it will be brought to your body.
Luckily you need to burn a lot of combustible in an enclosed space to get serious carbon monoxide poisoning.

Burning propane will produce many other byproducts, complex hydrocarbon and other gases which is not healthy to breath.

SO: when using your forge be sure your garage door is open.
This will take care of any noxious gases that may come out of your forge.
If your garage has some window, open it, so that a breeze can pass.
As for gases passing in your house, I don't think you risk anything serious.
Keep any door between your house and the garage shut and nothing significant will get there. You'll get much more hydrocarbon and CO from the normal air pollution of your environment than from your forge ;)
 
If I understand your question correctly, the dust generated in your shop will find its way into your furnace blower and then your home, unless you completely isolate the furnace. Steel dust is in insidious stuff...
 
I fear I misunderstood the question COMPLETELY :)
Well, just try to keep the shop as clean as possible.
I've bought a vacuum cleaner with an auxiliary power outlet you can wire your power tools to. When your drill or hacksaw start working, the vacuum cleaner kicks in automatically.
the model I bought can vacuum water and other non-flammable fluids too.
It's very practical :)
 
Make sure your furnace does not have a air pick up in your shop if it has block it off. If thats not possibe use a seperate heater for your shop,you don't want your shop air circulated into your house..
 
Allan, how do I find out whether there is air intake from the garage?

Thanks for the responses. The furnace also has its own little sliding door which mostly blocks it off from the rest of the garage, but there is some clearance between the bottom of the door and the floor (also some clearance on the top too) where air could get in.
 
Garages typically don't have an air intake because you wouldn't want garage smells circulating throughout the house.
 
Chang, I'm assuming your gas furnace for heating the house is forced air which blows warm air thru vents into various rooms in the house.

If so, the only real cure to keep knife dust out of the household system would be an external air intake for the furnace and sealing the room the furnace sits in, preventing intake from the garage air. You should get a furnace installer/repair to take a look at it and give you some options/ideas to solve the problem, estimates usually free.

Some furnaces are hot water heat which do not have ducts or vents in rooms but usually a radiator of some style in each room. These only move hot water thru the house and not air.

Both types of heating systems vent their combusted gas/air outside.
 
how do I find out whether there is air intake from the garage?
Click to expand...
The air intake is usally fitered,just trace the ducting from where you change the filter.
Regards, Greg
 
Chang, I'm glad you are thinking about safety. It can't hurt to think things through. Garages are notorious for leaking gases into the house. A study reported in my local paper showed toxic levels of carbon monoxide in homes from cars starting up in the morning, pulling out and closing the door. What this says to me is that fumes will be pulled into the house and minimizing their impact is worth doing. I second the recommendations to have a closer look at your heating unit or have someone else take a look. You might want to look at vapor barriers and weather stripping. Good ventilation also goes a long way.
 
Chang,

Is your furnace sitting open in the garage or is it in a closet?
Either way the cold air return will be in the living quarters of the house, this way the air will be circulated, all your heat vents should be high, unless it is a 2 story house and then the heat vents will be high in the lower level and in the floor on the second level, your cold air return will be a big vent down close to the floor or on a single level house it might just be vented at the bottom of the furnace inside the house. Your furnace should not be able to pickup any air from inside the garage, it will be vented into the garage but that will be just to blow heat into the garage. Check with your local furnace installer or better yet the company that installed the heating system in the first place, but I've never seen a furnace vented to use garage or outside air, it costs to much money to heat exterior air to the comfort zone in your house, especially when it colder than heck outside.

Hope this helps.

Bill ????
 
Bill, you're the man. Thats exactly the info I needed to know. I had never seen the furnace sucking air from the garage, but I was just worried. The furnace is inside a closet in the garage, and we have a two story house. The hot air seems to be coming out of vents in the ceiling on the second floor, and on the floor in the first floor. Thanks for the responses.
 
Bill's input was right on the money. The furnace heats air drawn from the interior of the house and returns it to the interior of the house. It draws air for combustion from the space it is installed in or from the outside through ducts or vents, it needs this air source to function properly. You should have an HVAC pro verify where this combustion air is coming from before sealing off the closet it's located in. Basically, the furnace draws in air to mix with fuel, that combustion heats a heat exchanger through which the house air flows and becomes warmer. If everything's working OK, house air and combustion (outside) air NEVER mix.

The biggest danger associated with having a furnace or any gas appliance in a garage/shop is the danger of igniting solvent vapors, gasoline leaking from cars, or things like propane from leaking containers. I've seen spectacular results from this occuring :eek: (I'm a disaster restoration contractor). Having the combustion air supplied from outside and then sealing the access (weatherstripping the doors, ect.) to the furnace will alleviate nearly all the danger. The same caution also applies to gas clothes dryers and water heaters.

Hope this helps,
Patrick
 
Democracy: three wolves and a sheep vote on dinner

Representative Democracy: the flock votes on which wolf will vote on dinner.

Constitutional Democracy: Voting on dinner is forbidden and the sheep have guns.

Bush Democracy: a wolf wears a sheep's skin

Clinton Democracy: a sheep wears a wolf's skin

Monarchy: only the wolf votes on dinner

Militarist Dictatorship: Only the wolf votes on dinner, and the wolf has a machinegun.

Theocracy: the flock worships the Wolf God who takes sheep and brings them to the Great Pasture

Anarchy: the flock is composed of wolves and sheep. There ain't shepherd or dog.

Utopy: wolves do not exist

Cinicism: sheep do not exist

Radical government with legal drugs: the flock is composed of pink vegetarian crocodiles, wolves dance can-can on the back of a butterfly winged brass elephant.


You should read "you have two cows" too :D
 
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