Replies

1. 
   MikeHennessy | Dec 26, 2006 05:05pm | #1

   Articles I've seen seem to indicate that you need far more suspended dust than normally found in a woodshop to cause an explosion. I have a small gas heater in my shop and have had no problems. I do need to blow the dust out of it once or twice a year. 

   That said, you will face a different sort of problem with the home's furnace in your workshop. The furnace will constantly be sucking up all that dust and distributing it nicely throughout your house (including in the ductwork). Your furnace will also acumulate a nice coating of dust inside it, requiring constant cleaning and your filters will plug quickly. In short, although you won't likely explode, a shop in the furnace room is not recommended.

   Mike Hennessy
   Pittsburgh, PA

2. 
   Dave45 | Dec 26, 2006 05:23pm | #2

   My shop is in my garage with the gas furnace and water heater on a pedestal in the corner.  The only problem I had (have?) was dust getting into the house.  It wasn't clouds of dust, but we noticed that things got dirtier during the winter.

   I fixed the problem two years ago by mounting a 24"x36" furnace filter over the open areas of my furnace so that the makeup air gets filtered as it's pulled into the burner chamber.  It seems to be doing the job.  When we did the pre-Xmas house cleaning, there was much less dust to deal with.

   Last year, I left the original filter in place all winter, but this year I'll be changing it more often.  It's been there since late October and that nice white filter is already a dingy gray. - lol

   If you use reasonable dust collection precautions in a basement shop, I think you'll be fine.  The amount of dust necessary to cause a fire or explosion would probably be well above your "comfort level".  I would be far more concerned with storing and using flammable materials in a basement shop.

1. 
   zolton | Dec 26, 2006 05:57pm | #4

   Hanging filters over the intake areas of your furnace is unlikely to have affected the amount of dust in your house. Combustion air drawn into a forced air furnace is completely separate from the house air. Combustion air is drawn into the firebox, combined with the fuel there (gas or oil), and then the combustion byproducts are vented out the flue. The house air passes behind and around the heat exchanger, and that loop is completely separate from the combustion air side. The two air sources are segregated, in fact, by the heat exchanger.

   Filtering the intake or combustion air by hanging filters over the intake openings will prevent dust from getting into the firebox, and there may be some safety value in that. However, it won't have any effect at all on the air inside the house. Instead, the filters might constrict the airflow needed for complete combustion (especially so when they get clogged with dust particles). So using the external filters may in fact make the furnace burn less efficiently - and more dangerously. The furnace has been designed to have air come into the firebox with no restrictions. Filtering it places restrictions on the free movement of that intake air, and that might be "starving" the burners of the air they need for complete combustion. Flames produced in such an environment burn "dirty," and produce much more carbon monoxide than ones that are not starved for the proper amount of air.  

   What might help to clean up the house air would be to carefully seal all the joints in the ductwork around the furnace. The most important of those would be the cold air return ducts. Those draw air in, and if the air in the garage contains dust, it can get inside the house via that route. Most of the dust coming in with from the cold air return should be trapped by the filter inside the furnace, but some always manages to sneak past even the best of filters. In fact, check out your filter slot as well. If that is open at the top or side in order to ease the insertion of new filters, then that's where a lot of dust is getting into the airstream - and likely blowing out into the house through the heat ducts and registers. Capping the slot with a sheet metal cover would help cut down on that source of dust.

   Sealing the return air ductwork should be of benefit from a safety standpoint as well. If you start your cars inside the inside the garage, you're producing a tremendous amount of carbon monoxide. Pull the car out and shut the door and you've just created a "balloon" full of carbon monoxide gas. Over the course of a day the CO can get inside the house via cracks and holes in the garage/house wall interface, and also can be drawn into the cold air return on the furnace (if the ductwork has not been sealed).

   Zolton

3. 
   Steinmetz | Dec 26, 2006 05:44pm | #3

   Biscardi, My shop was in use for 40 years right next to my gas fired furnace, With the door separating the two rooms closed, I had no problems all year long.In winter, I had a freestanding gas fired heater
   right in the shop still no problem. (Only used it occasionally) No prob. I now work from my son's basement and I closed in the oil fired boiler with a door and two filters also vented it for outside air.. SWEET!

   Steinmetz

4. 
   JMartinsky | Dec 26, 2006 05:58pm | #5

   Dear Biscardi,
   Blowing up the house with a dust explosion would be a tall order. The concentrations required would drive you out of the shop well before there was "critical mass". Dusting out your furnace is another matter altogether. I always recommend that burners be vented directly to the outside, so that the boiler / furnace, is drawing in fresh, outside air , instead of inside air. As homes get tighter, there is less make up air available. I have always let the oil or gas companies install these. It is typically a 4" duct that runs directly from the outside to the burner. This will close out the system from inside and will minimize any dust drawn into the burner.

   Best,

   John