My shop is in the basement of my house I have both a DC system and a air cleaner.
They work pretty well keeping the dust in the shop to a reasonable level. However, what is reasonable for the shop isn’t for the rest of the house. Even with the doors closed, my wife insists that I am reasonsible for a fine layer of dust in the house.
I am thinking that I need to create a low pressure zone in the shop so air flow in the house is into not out of the shop. Living in New England, I am not to excited about the easiest way to do this. putting a fan in the window.
Has anyone used one of the HRV(heat recovery ventilators) to accomplish this??
Thanks in advance for your comments.
Replies
Toolin,
I though this was about deadlines or being broke. ;-)
I don't have one, but as I understand it they would work well.
Mike
Toolin -
If it's possible you could route the exhaust for your DC to the exterior and put the filter bags of cannister out there. This would, of course, pull your heated air out of the house but it would only be while the DC is running. To take it a step further, build an enclosure (outdoors) for the filter bags or cannister, then install a return duck back to the shop to reclaim the conditioned air. In the return you'd want to put a high effeciency filter of course, otherwise you'd be defeating the purpose.
We have a low volume heat exchanger for the house now that we have a non forced air heating system. Such things are available and do reclaim much of the heat that would be otherwise exhausted to the outdoors. But they require pretty fine filtration so as not to clog the whateveryacallit that does the heat exchange.
From Beautiful Skagit Co. Wa.
Dennis
The major source of the house dust could be carried in on your work clothes.
IanDG
If your house's air returns to the basement for conditioning and distribution upstairs then your wife may be right. Make sure that the entire trip to and from the basement is ducted and well sealed.
I work in hospital renovation. Keeping dust in the jobsite is literally a matter of life any death for immuno-suppressed patients nearby, and we often do not have an exterior wall through which we can exhaust dust and negatively pressurize the site. We create the negative pressure by pulling the jobsite air through a filter assembly (3-stage rough/pre/HEPA) and exhausting it into the hospital. Ironically, we are keeping the rest of the hospital clean by exhausting air into it, very clean air that is then sucked back into the jobsite through construction cracks and around the doors. It works. We use pressure monitors and particle counters to verify conditions.
It would be fairly easy to set this up between your basement and the house above. Use the correct filters and meticulous sealing of the airpath to prevent dust getting around the filter bank. You might get good results for less by substituting the best version of 3M's Filtrete series filters for the HEPA. They are close to HEPAs in performance, though they don't have nearly the dust capacity.
I also echo the previous advice about clothes. Consider keeping shop clothes in the basement.
Are any of the heating/cooling ducts for the house dumping air into your shop? Or are you just fine under the house without any heating/cooling.
I wasn't sure from your question if you were isolated from the house system.
I tapped into the house system for my shop. It's forced air so tapping into a supply and a return wasn't hard. I put a large house filter in front of the return to filter the return air. If I do any work with finishes or create any noxious fumes that the filter wouldn't catch I shut off the return till they subside or I open the shop up to outside to vent it. So far, so good. Our house isn't that clean anyway and the filtered air going back is as clean or cleaner than the house. But don't tell my wife that!
Edited 2/26/2005 9:17 am ET by david
The house is Hydronicly(sp?) heating. no forced air ducting.
The clothes thing is a definite possible source as well. Will keep that in mind.
Interesting idea about super filtering the air and blowing out of the shop into the main house. That could work. I actually have a small section of finished basement next to the shop and an easy wall to work with.
I wonder roghly how much CFM I would need to keep the negative pressure.
Should I remount my aircleaner with the exit air thru the wall and upgrade the filters??
"The clothes thing is a definite possible source as well. Will keep that in mind." Don't forget your hair. Hang your head down and ruffle your hands through it before you leave the shop.
My apologies if you don't have any/much. Not trying to be mean, LOL!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Something we did In construction was to blow off a lot dust with compressed air when we went to lunch. You could do that before you left the shop.
Do you think a bathroom vent that is normally used above the toilet would be enough to create an airflow? You could wire it into the lights so when you turned them on it would turn on as well. It certainly would be inexpensive.
I wonder roghly how much CFM I would need to keep the negative pressure.
The amount of air moved depends on the resistance of the air leaking into the shop, which is a function of both the amount of vacuum you pull and the total amount of open space (under doors, through receptacle openings, etc.). The better you seal the space, the less air will be pulled through, and the less heat will be lost if exhausting outdoors.
The best fan to use for maintaining such a low-flow vacuum is a squirrel cage blower, like in a furnace, though a smaller one should suffice (assuming pretty well sealed shop). The less air they get, the less current they pull, so there's no chance of overloading and burning the motor (unless you open a window and let it move too much air - many are not rated for free-air delivery, and need some resistance). A local HVAC contractor should be able to fix you up with a small, direct-drive squirrel cage blower from a scrapped air handler, often for free, or a couple of bucks at the most. They're headed for the scrap yard anyway.
Propellor fans, like window fans, are the opposite, and the motors are likely to overload and burn up if the restriction is too high. Those cheap box fans with the plastic blades don't seem to have that problem, probably because they have very shallow, slow moving blades, and can't generate much static pressure. But I wouldn't use one of them anyway.
If the shop is pretty tightly sealed, you'll find very little air being exhausted, and very little heat with it. You're just trying to maintain a vacuum, like a vacuum press - the only air being moved through them is whatever air leaks into it while it's running. If you can't seal it up very well, then a recirculating filter system would probably be indicated, but that's going to be more expensive, and require some filter maintenance.Be seeing you...
This forum post is now archived. Commenting has been disabled