Spark/flame sources in the shop

[David Lein]

Hi everyone. I'm trying to put together my first attempt at a shop and have very limited space options–basically it's a basement space about 14 x 22 x 7 versus a small detached garage. The former houses my gas-fired hot water heater and gas furnace, and the latter my '67 Ford F100 and daily driver. I'd prefer not to kick one (or both) vehicles into the elements, but I'd also like to avoid turning the woodshop into kindling for the rest of the house. Given dust collection (a Steel City 1hp dust collector plus a Jet air filtration unit), am I running a significant risk with keeping shop in the basement with a couple of sources of flame? Any thoughts on this would be appreciated; my electrician is a little dubious. Thanks in advance.

David Lein

[Joe Chritz]

Any dust not captured by the collection shouldn't be a problem.

Any kind of fumes, such as thinners, finishes and the like that are not waterbased will be.

Before I built my outbuilding shop I had one in the basement. I didn't use any flammable liquids at all in it.

You may want to think about closing off the water heater and furnace so it doesn't draw dust filled air for combustion.

Joe

[David Lein]

Thanks Joe. Yes, I was planning on keeping the flammable solvent use elsewhere. I'd considered walling off the furnace and water heater but that would be a pretty significant projection from the middle of one of the long walls, and I kind of wanted to maximize the available space. I'd been thinking as you, that as long as the dust was kept to a minimum it shouldn't be an issue fire hazard-wise.

David Lein

[Brian Dormer]

My shop (14 x 18) is smaller than yours - but in a basement with low ceiling and not far from the furnace and water heater (they are in another room - about 2 walls and 15 feet away). When I built the shop, I installed a bathroom exhaust fan right over the "paint table" - where we spraypaint, use smelly glue or do anything else that stinks. The fan is on a timer switch that has ON and TIMER (60 minute) options. Before anything smelly or dusty comes out - the fan goes on and when leaving the shop for the day, it goes on the 60 minute timer. My rather crude calculations show that the fan can change the air in the shop about 4 times an hour. That's probably a little optomistic, being ADVERTIZED, rather than measured airflow - my guess is more like 2.5 - 3 changes/hour. Due to the negative pressure the fan sets up, it keeps the fumes in the shop surprisingly well.

If the weather is nice - I still prefer to do "smelly stuff" outside - but in the winter, this works great.

I also have a small shop vac (with HEPA filter) I use on some tools and a 3/4 HP DC (.3 Micron bag) that I use on the TS and other big tools. This keeps the dust down to a very tollerable level.

If one fan didn't do the trick - I wouldn't hesitate to install a second fan.

I've cleaned large metal parts with ACETONE and other chemicals - which is highly flamible - and never had a problem. You can also look at less flamible alternatives (I now use an orange based stipper and save the Acetone for really tough spots).

I wouldn't want to pour a gallon of acetone on the floor and crank up the (gas) furnace - but a couple rags with a an ounce or two shouldn't be a big problem if you have some airflow (you should probably wear a resperator with appropriate filters though).

Unless you are using some VERY nasty/flamible stuff - I don't think you have much to worry about. And you have options to mitigate the fumes....

[Mark Visconti]

Note : I'm not an HVAC guy - do we have one at SMC? I'm in the same situation as the OP - basement shop with gas furnace - DC will be Cyclone and an aircleaner capable of changing the air 6 to 10 times per hour. I won't be finishing near the furnace - will either take it outside or to a space several rooms away.

Is it safe to build a small enclosure around a gas furnace ? Would the enclosure need a ventilation fan ?

Isn't the airflow coming from the cold air return and not from the surrounding area ?

I'd rather double the number of aircleaners and add a fan to push air away from the furnace than to deal with having to enclose the furnace in drywall (built around the ducting) and put up at least 3 access panels for access for service and for filter changes. I'm space limited as well.

Unfortunately, usually when I'd rather do something else to fix a problem, it means I should be doing it the harder way.

[Al Willits]

fwiw
If you close off the furnace and water heater make sure of at least two things, combustion air and being able to service these.
Run into this all the time, had a cust wall off their furnace with sheet rock and build a bathroom on the other side of the wall the furnace axcess was on.
Wasn't to happy his stool had to removed so we could fix his furnace.

Also the exhaust vents needs clearance from combustibles too.

Al

[Joe Chritz]

Check your furnace manual. Some need lots of air, some newer models don't take any inside air for combustion. Most water heaters (all I've ever seen) use inside air for combustion and will need some free space to breath.

The clearances and free space will be listed somewhere with the equipment. You can get the available air by using vents in the enclosure which can then be covered with filters.

Joe

[Andrew Williams]

I had a device installed with my new boiler called a "fan in a can" that brings in outside air when the oil burner kicks on.

In terms of using a fan to remove explosive vapors, AFAIK explosion-proof fan motors are quite expensive, although to be honest, I have heard no stories of home shops exploding due to using VOCs (doesn't mean it didn't happen). Perhaps if you were spraying a lot of finish then you could get up to explosive concentration. I would just use an ordinary fan to exhaust the bad air UNLESS you are making a spray booth, in which case it needs to either be an explosion-proof fan or make a belt-driven unit with a remote drive motor.

Please note that I am not an expert on the subject and am only giving my available information and feel free to disagree or add to it.

[Rick Christopherson]

By closing off your furnace, you can actually create the situation you are trying to avoid. Materials will not combust when their concentrations are above or below their combustion concentrations, and as long as you have moving air through the shop, you won't reach these levels.

[David Lein]

I should have mentioned I have an old gas boiler–I'm sure the manual was lost a couple owners ago–for a hot water heating system. I'm going ahead with having the subpanel for the 220v outlets and dedicated 110v circuits installed, and plan to exclude the volatile solvents. I like the idea about improving fresh air flow with an exhaust fan. I hadn't thought of that. Anyway, thanks for everyone's thoughts on this, and for helping out a relative newbie woodworker get going with my first dedicated shop space.

David Lein

[Andrew Williams]

Food for thought:

Large combustion devices like boilers and furnaces live on oxygen, just like we do. They eat up quite a bit of it too. One of the reasons I had the fresh air input fan installed was because even if I never closed off anything (which I didn't anyway) I wanted to breathe as much oxygen as I could, not give it all to the heater.

Another thing: If you decide to have an exhaust fan without a fresh air input, remember that you are creating a pressure drop in the basement. That pressure will have to relieve itself via the path of least resistance, which most likely will be your furnace flue. This can create all sorts of problems with proper exhausting of the waste gases of your furnace, and when the furnace is not operating can also bring chimney crud back into the space via the reverse airflow.

YMMV