Replies

1. 
   Shanefe | Mar 12, 2005 02:16am | #1

   I would say that plastic sheets are not going to be enough.  You would be better building a walls.

   Sounds like you will need to collect all the dust at the source.  You will need to buy a good 2+ HP Dust collector.  Skip the filter bags, go striaght to Filter Cartages and make sure that they are +90% at 1 micron.  Use 6" pipe to collect the dust from the tool.

   Throw away your dust blower and buy a good one with a pocket type filter. (or rebuild your to use a pocket type filter).

   You can solve the problem but it will not be inexpensive.

2. 
   Midnight | Mar 12, 2005 02:22am | #2

   Mitch... what I know about HVAC you could write on the business end of a needle so I won't go there...

   Reading your post I thought... wouldn't it be better to treat the cause rather than the symptom?? If the dust is accumulating to concerning levels in the HVAC, then it's also gotta be getting to other places it isn't supposed to. That raises the question,- can you improve your DC... not just the shop filter (which obviously isn't doing enough) but maximising extraction at the source of the prob...

   I was facing the exact same prob, any time I fired up the sander, jointer or thicknesser, the living room would aquire a heavy dust covering, this in spite of using the DC and shop vac whenever necessary, and having the shop door closed.

   Upgrading the DC wasn't an option; both budget and shop space were sadly lacking. Next best option open to me was to cut the quantity of dust I produced... For me, the solution lay in hand tools... I've all but retired the thicknesser, the jointer hasn't been used in 2 years and the only time I use the sander is when working with ply; I'm still hunting for the last component I need to let me hook the sander to the shop vac..

   Granted, what works for me won't suit everyone in your situation... however, the alternatives need to tackle the same probs..

   Can you build an enclosure for the HVAC, sealing it off from your shop?? Is it possible to house your DC outside and run a duct to your dust-makers?? Can you add dust extraction to the table saw blade guard (for example)? Can you change the bag filter for a cannister type on your DC...

   There's a bunch more permutations that I canna think of right now, and without seeing your shop it's impossible to advise which solution might be the more practicle.. With any luck, this'll at least point in the right direction though...

   Mike Wallace

   Stay safe....Have fun

3. 
   tms | Mar 12, 2005 02:36am | #3

   Hey Mitch,

   You, my friend, need a real dust collection system. By that, I mean a ducted system that will remove the dust from the source, BEFORE it gets into your breathing air. Get one that filters down to 0.5 µm. It will cost you, but you would easily put the same money down on a bandsaw, but what price for you and your family's health?

   Also, do not delay getting your HVAC ducting cleaned. There are plenty of contractors out there with vacuum trucks. It's a competative business, so get some quotes and take care of your family home.

   You will never regret doing this the right way.

   Good luck,
   Tom

4. 
   MarkRD | Mar 12, 2005 03:21am | #4

   This is strange. My furnace is in the same room as my shop and, while it gets dusty, is no where near as bad as you describe.

   Couple of things. All the returns to my furnace are sealed - that is the 8" pipes are normally just screwed together, I went back and duct taped all the seams - it cut down considerably on the dust that gets into the heating loop.

   The makeup air for the flame comes from the shop - that I can't address right now, so that means that the "fire box" area gets dusty but little dust gets into the heating loop (it's a loop of heating duct, the house and the return pipes - the heat transfer occurs across a heat exchanger the flame is on one side of the heat exchanger, the cool return air is on the other side...

   Eventually, I will be close in my furnace and feed it air from the outside directly - that will isolate it from the shop, and it will get fresh cold air to burn (which increases the efficiency a bit too)...

   So, to start, go around and seal all your return and heating duct work. Also look for screw holes in the duct work (if the pipes have ever been taken apart and put back together, there will be extra screw holes because they never line up just right). Duct tape is fine, but the metalic (and very sticky) tape is better (but wear gloves, the edges are quite sharp!)

   That fifth pic you post (dust in the corners) I'm assuming that is dust that was drawn to the furnace not the other way around. Somehow you'll have to seal those holes...

   Also the round corner pipes have pieces that slide together - tape those too!

   Mark

   Measure it with a micrometer, mark it with chalk, cut it with an ax.

5. 
   AndyE | Mar 12, 2005 03:25am | #5

   I feel your angst. A filtration system only gets the dust that is already in the air. It won't catch it all no matter what you do. You should invest in a DC, even if it is one of the small units you roll around and attach to each tool as you use it. That gets the majority of the dust at the source before it spreads.

   I have a similar but different situation. The basement of the addition is my shop, 24' x 36' L that is roughly 11' 6" wide. Old foundation wall is still in place so mine is separated from the rest of the basement, at least it is now that I have the door installed. The HVAC ducting for the addition runs through the shop. When it was installed the tech refused to cut in an opening for the shop saying that it would backdraft in the cooling season due to pressure differentials and humidity blah, blah, blah. Tech said it would pull in all sorts of sawdust, blah, blah, blah. Sold me a thousand dollars worth of electronic, electrostatic air filter. Said it could be cleaned in the dishwasher. NOT. Well, tired of working in a 50 degree shop I cut myself a vent this winter and installed one of those louvered vents with a gate to close it off. I also have some of the magnetic sheet vent cover stuff to seal it off some more. I digress...

   Your photos show dust being sucked in at the seams of the ducting. Get yourself a few rolls of the aluminum furnace tape, NOT "duct tape", and seal every joint, seam and crack you can. That is unconditioned, unfiltered air being pulled into the returns and blowing out the supply of your system. Is it feasible to build a set of removable panels to wall off the woodworking area while you are using it? Even something simple like luan and 1x framing. Is it possible to put a 6" vent pipe with an inline fan through the wall to the outside to create negative pressure in the shop area while making dust? You would have to open a window or door to the outside for makeup air so the furnace won't backdraft. I use a similar technique for when I'm finishing and it works pretty well.

   Dust control needs to be the first line of defense. For the sake of your lungs and so the entire basement doesn't become a dusty nightmare that will just cause other problems.

   Good luck, hope this helps. Let us know how you solve this.

   AndyE

   P.S. Next time you have the HVAC techs coming, dust the place before they show up so they don't ask so many questions.

1. 
   btrouble | Mar 12, 2005 06:06am | #6

   Mitch,

   You had some good advice from some of the other responses when they recommended that you seal out the dust from your htpump air handler unit with ductape. Although ductape is a good idea, it is not a permanent lasting solution for your problem. What most hvac people use these days is duct mastic which comes in one gallon or five gallon tubs to seal off holes, cracks, etc. in the seams and joints of a duct system. With the cracks I saw at the duct seams and air handler, it's a wonder that your whole family isn't sneezing from the wood dust! You can "paint" the seams and joints on your ducts with duct mastic and anything a 1/4" wide or wider will need re-inforcement with fibreglass tape(available at any hardware store as sheetrock tape). An hvac dealer should be happy to provide you with the mastic. I also saw a big no no as to how your air filter at the air handler was installed. There are gaps both in front and behind the air filter and no cap over the filter so that only house air passes across the filter. At the very least, you should probably ductape over the hole where the filter slides in. Without doing that, the filter does only half the job. By the way, the claims of the air filter manufacturers that you  need only change those filters every three months belies the fact that they do not have to pay your fuel bills. Leaving them unchanged longer than a month makes the filtration fairly efficient but it will make your heating or cooling costs soar. A plugged filter filters better but the airflow suffers tremendously. A cheap paintbrush 3 inches wide, about 10 to 20 bucks of mastic and a roll of fabglass tape along with some ductape will solve keeping wood dust out of your house. Then, perhaps you can work on a dust collection system to get that out of your shop!

    

   Bill

   Edited 3/11/2005 10:13 pm ET by btrouble

   Edited 3/11/2005 10:14 pm ET by btrouble

6. 
   TomFerreira | Mar 12, 2005 07:14am | #7

   Mitch,

   I disagree with some of the posts that argue for a complete dust collection system. Don't get me wrong, dust collection is important but I don't think this is the solution to your problem. I also don't think you need to seall all of your ducts. The fact is that the output from your bloer is all positive pressure and is not pulling duct into the system. Th dust is coming from the input side of the blower where the internal pressure is negative. In the picture that shows your filter there are a lot of gaps around it. This is where I would start. Seal this up somehow. I wouldn't use duct tape because you need to replace the filter periodically. Then look for other leaks on the low pressure side of the blower or the air intake especially on the blower side of the filter. This is the air which is not getting filtered if there is a leak. It also looks to me like your filter doesn't fit in the channel or housing very tightly. I would look at this because if it doesn't it will not be very effective.

   Good luck!
   TDF

1. 
   tms | Mar 12, 2005 07:23am | #8

   Hey Tom,While you've accurately described the HVAC problem, you've also skrited the more serious problem, in that, the dust that enters the HVAC is in the breathing air of the shop! The airborn dust in the shop presents a serious health threat to Mitch, his family, and anyone else in the shop. In addition to the dust in the air, any dust that settles, can easily be re dispersed to creat a hazard at any time.Removing the dust from the source will make the shop a healtiier place to work, AND solve the HVAC problem.Tom (tms)

1. 
   mvac | Mar 12, 2005 06:12pm | #10

   First of all, let me thank all of you for taking the time to give me the benefit of your advice and experience. Second, I'm experimenting a bit here by trying to send a copy of this message to each person who sent me a message by putting your user ID, instead of your e-mail address, in the area where it says you can send messages to others w/ e-mails. So if you DO get the message separately, please let me know. Now I'd like to address each response:

   ShaneFe - I've thought about building walls around the heat pump, but I may not have the clearance, I don't know if it's code-compliant, and one of the later posters mentioned something about pressure change problems that could be caused by sealing in the heat pump - not so sure about that last one. As for the DC, the tech felt that no dust collector would catch enough dust to avoid a recurrence of the problem. I still think a DC's a good and necessary thing, but money's tight right now. And as for my shp-built AFS, take a look at it and tell me if you still feel the same way. It uses a 3 amp, 240 volt squirrel cage blower fan and generates at least 1200 cfm. I don't think I can do better with a prefessionally made one, but if you still think so, please do tell me why. Finally, what's a pocket-type filter? Is it not what I have on the AFS intake and exhaust?

   Mike - Hand tools? Do I have to start mentioning sheep and kilts again? Seriously, I love my hand tools, but I value my time even more, and the whole purpose of the machines is to save that precious commodity, as well as to add a degree of precision that's much harder to attain by hand. Also, have you or anyone else figured out a way to suck more dust from a handheld orbital sander or belt sander? They both have bags, but that's almost a joke...

   tms - Yes, my friend, I do need a real dust collection system. Please send your check or money order (remember, don't send cash) to Mitch Scott at ... well you get the picture. And I'm definitely getting the HVAC ducting cleaned ASAP, which will probably cost me more than a DC system. So, I'm doing what I can... Btw, I always wear a dual-cartridge paint/fume-graded ventilator when I'm making dust, in addition to having the AFS on, so I'm taking decnt care of my lungs, I think...

   Mark - I think sealing the ducts and the area around the filter is a great idea, and one that has no downside to it. So I'll be doing that right away. I may use some of the stronger selants mentioned later in the thread. I have an electric heat pump, not a furnace, so I don't think I have the same need for fresh air to feed the heat pump.

   AndyE - As I mentioned before, I can't afford a DC right now, but  do hook up my shop vac to the TS, Planer, disc/belt sander, router table, etc. I think aluminum furnace tape or the dust matic that Bill mentioned in the post after yours is also a great idea. Also, sealing the area around the filter is a no-brainer, now that I know how much damage was caused by not doing it. I have to think about the removable panels idea - that might overcome any clearance issues, and since they'd be removable, I wouldn't worry about code issues either. As for a vent to the outside, my shop is entirely below grade, although the utilities come in from above grade down into the shop. So I'm looking at that, but a) it'll probably be expensive, b) it might create problems with negative pressure, and c) if it's powerful enough to do the job, it's probably powerful enough to freeze the family jewels during the cold months. I agree, dust control is of paramount importance, but I can afford mastic or furnace tape now, so I'll do what I can with that, and maybe the removable panels.

   Bill - Thanks for the mastic idea. That sounds like the way to go. Is it not available at the big box HI stores? If not, there's a HVAC supply place near me, and they my have it. I've gotten the message on changing the filters monthly. But that raises the question - is it worth it to by Filtrete or a similar premium filter if I'm going to change it monthly? Thanks again for the advice.

   Tom Ferreira - I'll be sealing up the filter before you get this post, trust me! And as far as sealing the joints goes, is there a downside to it that you see?

   Tom (tms) - I hear you when you speak to the health hazards associated with the dust. That's why I built the AFS and where a dual-cartridge vapor-rated ventilator mask when creating dust. But even if I did have a DC system, how do you deal with dust creators like the handheld router (I have a PC 890) and handheld sanders?

   Once again, thanks to everybody. And do let me know if you get a message notification or not.

   With gratitude, even to that crazy Scotsman ;-),Mitch

   "I'm always humbled by how much I DON'T know..."

1. 
   tms | Mar 12, 2005 07:27pm | #12

   Hey Mitch,I did not get an email, sorry.The best way, that I know of, for dealing with handheld dust makers, is to build a downdraft table. Usually, this is a table with a perforated top and a plenum connected to a squirrel cage fan (from a defunct furnace) that uses furnace filters to collect the dust. They can be very effective.I'm surprised to hear that cleaning your HVAC will cost as much as a DC. Around here, it's quite reasonable, as I mentioned earlier it's a competative business. I had my small house done a couple of years ago for less than $100.Tom

1. 
   mvac | Mar 12, 2005 10:59pm | #16

   Tom,

   "I'm surprised to hear that cleaning your HVAC will cost as much as a DC. Around here, it's quite reasonable, as I mentioned earlier it's a competative business. I had my small house done a couple of years ago for less than $100."

   I just want to make sure we're comparing apples to apples; I may not have described the problem properly. The cleaning issue has to do with the fact that, according to the tech, there's dust in the coil, motor and fan, and apparently not a small amount. That's what needs to be cleaned out, regardless of how I choose to address the problem of dust getting into the system going forward. I suppose it wouldn't hurt to have the ducts cleaned, too, but I imagine that would be less costly.Mitch

   "I'm always humbled by how much I DON'T know..."

2. 
   Midnight | Mar 12, 2005 09:23pm | #14

   Hand tools? Do I have to start mentioning sheep and kilts again? Seriously, I love my hand tools, but I value my time even more, and the whole purpose of the machines is to save that precious commodity, as well as to add a degree of precision that's much harder to attain by hand. Also, have you or anyone else figured out a way to suck more dust from a handheld orbital sander or belt sander? They both have bags, but that's almost a joke...

   So yer sayin ye dinna ken how t use yer hand tools ehh...?? ;P~ As for costing you time.. how long are ye spending going round the entire basement in yer wee french pinny and feather duster..?? <thinking the steel toe capped 3" heels are a wee bit over the top... buttttt each to their own... just do me a favour... dinna bend over in yon wee short skirt... some things in life I dinna need t see.... trust me...!!

   Sanders are always a prob.. 3 years I've been trying to track down the supplier o the poxy wee adaptor to interface my Bosch ROS to the shop vac... Short o that... like I said, best solution is not to use em.. but if ya must... have you thought about a downdraft table..?? In the mean time... splash out on a card scraper and burnisher, learn how to use em and keep the sanders on the shelf till you can figure how to minimise their mess... trust me, you'll save a bunch of time when it comes to clean up...

   As for the DX upgrade... spend some time on Bill Pentz's site and heed well what he's saying...

   http://billpentz.com/woodworking/cyclone/index.cfm

   edited cos I'd forget my heid if it wasn't bolted on....

   Mike Wallace

   Stay safe....Have fun

   Edited 3/12/2005 1:24 pm ET by Mike

1. 
   mvac | Mar 12, 2005 10:55pm | #15

   "So yer sayin ye dinna ken how t use yer hand tools ehh...?? ;P~ As for costing you time.. how long are ye spending going round the entire basement in yer wee french pinny and feather duster..?? <thinking the steel toe capped 3" heels are a wee bit over the top... buttttt each to their own... just do me a favour... dinna bend over in yon wee short skirt... some things in life I dinna need t see.... trust me...!!"

   When I stop laughing long enough to reply seriously, I'll let you know...Just picture me gasping for air between guffaws...Mitch

   "I'm always humbled by how much I DON'T know..."

2. 
   btrouble | Mar 14, 2005 04:37am | #20

   Mitch (and Tom),

   What I was saying and possibly did not put across very well is that the suction side of the blower(negative as Tom said) should be sealed to keep out the dust for both the health of your family and also prevent the possibility of fine dust being ignited by the blower motor or by the backup electric heat strips on the heatpump. BUT! In order to keep the positives and the negatives in balance on your hvac system, the supply or positive side of the blower system should also be sealed. Just think of it this way. You want the same amount of airflow entering the house as you pull from it due to the return airflow or you have the duct system breathing positive pressure out around the doors, windows, light switches, and every little crack in the house structure with a well sealed return but not very well sealed supply. The opposite occurs with a sealed supply duct system but not on the return. Okay, I can see I am starting to get into things that will require too much explanation but I can tell you that I do know what I am talking about here. I have been in the hvac business for more than 45 years. Tom, I was talking about sealing the gap over the filter with ductape for a temporary seal that would be renewed monthly when he changes his air filter. Yes, the inlet is way oversized for the thickness of the filter but I doubt if his hvac company would change that now. He could slide in pieces of self adhesive foam and stick those to the sides of the rack(available in various widths from the hardware store) to reduce that. Mitch, with the problem of the fine dust it is even more important that you keep a higher efficiency air filter than normal in your system simply because the blue fiberglass ones you buy at the grocery store only stop 2 to 7% of the dust and dirt. Someone else brought up the health concerns of the fine dust as well.  I don't know if the big box stores carry duct mastic. I have not seen it in HD, Lowes or any other around here(SC & NC). You do want to keep the dust out of the return duct system because ultimately that fine dust goes through the supply system to the rest of your house! Isn't your wife complaining about having to dust all the time? I liked what someone else said about possibly walling off your htpump system from the workshop areas with plastic but I do not know how practical that would be. Okay, I may or may not have answered all of your questions but I have typed enough for the present. I hope that this helps. BTW, there are different grades of throw away high efficiency air filters available. Besides Filtrete, there are ones that go from $4 to$12 but each one that has a higher resistance and dust arrestance than the next also reduces the airflow to your heatpump system. Going too far could cost you a compressor due to insufficient airflow across the indoor coil on heating causing high compressor winding temps. A good system would have a manually resettable high pressure switch to prevent this or at the very least a self resetting hp switch. The pleated filters in the midrange prices do a good job if the filters are set in tight in their rack/frame.  Even with the compressor in warranty, the labor, refrigerant, silver brazing, etc. for the compressor change may not be covered.  Your air handler looks like a Trane(American Standard) so it should have protection on the outdoor unit. I keep seeing stuff I did not respond to. In your first picture of the hp ahu, the dust coming out of the corners is on the supply side which means that dust is going inside the rest of the house. When you duct mastic seal, you need to seal the joint between the bottom of the blower and the sheet metal plenum it's sitting on as well as the joints on the ells on the return ducts I saw and every single "line" of metal to metal, metal to wood(shows in another picture), the joints of the ducting where it is put together(what we call s's and drives on the rectangular duct), etc. It sounds difficult but it is not except where access is tight for a man's hands. You might be surprised how much cleaner the system operates after sealing the air filter location(temporary)and you should notice better dehumidification in the summer. Your bills will definitely decrease if you do the sealing properly. As to cleaning the indoor coil, that is best left to your hvac tech since he will have to cut a hole in the plenum to access the back side(it's most likely a slant coil arangement) but you could blow/vacuum out the blower wheel and fan motor yourself relatively easily. Gee, I have offered way too much info now! Time to hush.

   Bill 

   Edited 3/13/2005 10:11 pm ET by btrouble

   Edited 3/13/2005 10:26 pm ET by btrouble

1. 
   mvac | Mar 14, 2005 05:27am | #21

   Bill & Tom,

   Thanks a lot for your detailed comments, both of which I intend to act on, to the extent possible. I don't think, Tom, that I'm in a position to vent air outside or create another vent to equilibrate the pressure (eh, fancy word, there, huh?).

   That said, sealing off the shop makes a lot of sense, and that I'll do.

   As for sealing the gaps in the filter area and all around the ductwork, I've already bought what materials I could find for the job. The aluminum HVAC tape was no problem; but I couldn't find duct mastic. I did, however, find this very inexpensive clay-like substance called - wait for it - duct sealer. I'm thinking, Bill, that using the sealer under the HVAC tape would be akin to using plumber's putty or teflon tape to secure the seal. Does that sound reasonable? If not, I'll just use the tape or look online for the duct mastic.

   Btw, there's an online place, Troy Filters, that stocks the full range of filters at very reasonable prices, so that's where I'm going to get mine.

   Let me know about the duct sealer as an alternative to the duct mastic, if you don't mind.

   And thanks again for the advice.

   Best regards,

   MitchMitch

   "I'm always humbled by how much I DON'T know..."

1. 
   btrouble | Mar 14, 2005 05:45am | #22

   Mitch,

   I am thinking that you bought "duct sealer" as in the grey clay stuff for sealing off electrical boxes, etc. to keep them watertight? As far as I know I believe that you could use that. Barring finding anything else, I was going to recommend silicone caulk but that really makes for a messy job on your hands (and it doesn't come out of clothes either!). It would last as long as you used the "wet finger" method to push it into the cracks. You shouldn't need to tape over the duct sealer and I am not sure that it would stick anyway. Although I am familiar with the electrical duct sealer, I haven't used it in years. The only problem might be that the sealer dries out, cracks and falls off. Duct mastic stays permanently flexible so it won't crack unless put under severe stress. The fiberglass tape reinforces the larger)1/4" or more) cracks. Duct mastic is prevalent in the Southeast with at least 98% of the hvac companies. I am not sure about the rest of the country. Probably not in the Northeast where basements are more prevalent. BTW, duct mastic also ruins clothes permanently unless you get them off and in the washer before it dries.

    

   Bill  

1. 
   mvac | Mar 14, 2005 05:52am | #23

   Bill,

   Thanks for the quick response. I think we're talking about the same thing, especially since I found the duct sealer in the electrical section (hint, hint...).

   I'll try it. Do I lose anything by going over it with the HVAC tape, being a belt and suspenders kind of guy? I'm also thinking it would be an added precaution if the sealer did turn out to dry out or crack. And I'm not all that thrilled about ruining my clothes, even if I don't wear my finest into the shop.

   Best regards,Mitch

   "I'm always humbled by how much I DON'T know..."

2. 
   btrouble | Mar 14, 2005 06:02am | #24

   Mitch,

    

   I suppose you could try it on a short section to see if it would stick. If the clay is damp at all, I can tell you it probably will just make the tape fall off. The adhesive on ductapes won't stand anything wet or damp. If this sealer is like plumber's putty I think that you could roll out lines of it to press in place like the mortite I buy from the hardware store for sealing around the sink drains.

    

   Bill

3. 
   Midnight | Mar 14, 2005 11:29pm | #25

   And I'm not all that thrilled about ruining my clothes

   ummm... can I suggest... coveralls..??

   Ohh...an dinna worry about em makin yer bum look big... the way ya keep bending, trust me,  they're a blessing.!!!!

   ;P~~Mike Wallace

   Stay safe....Have fun

4. 
   mvac | Mar 15, 2005 11:30pm | #26

   Actually, I thought they accentuated my hips...

   But seriously, if a guy who's been in HVAC for 3 decades is tellin' me something's gonna ruin my clothes, I'm gonna try and steer clear of it. The only other tradespeople likely to get dirtier are plumbers and chimney sweeps...Mitch

   "I'm always humbled by how much I DON'T know..."

5. 
   Midnight | Mar 16, 2005 12:33am | #27

   <shakin head slowly....

   did yer mither never teach ye nae t wipe yer hands on yer backside..??? Talk about clarty... sheeshhh...

   As for accentuation.. ummmmmmm.... I'm way too sober to think about going there...

   ;)Mike Wallace

   Stay safe....Have fun

7. 
   mvac | Mar 12, 2005 04:57pm | #9

   This is a test. Mike, did you get a copy of this?

   Mitch

   "I'm always humbled by how much I DON'T know..."

8. 
   DennisS | Mar 12, 2005 06:36pm | #11

   mvac -

   Seal your shop from the rest of the house. Make sure the shop area is under negative pressure so no air gets out of the shop and into the rest of the house. Where is the return for the heating system? Is it a central return located in the basement? Clearly the return is sucking air from the shop as well as the rest of the house.

   I worked for years in my garage right next to my forced air furnace. The cold air return was on the other side of the wall such that it wasn't sucking air from the garage, for obvious reasons. Airborne dust from the garage wasn't a problem of any major consequence.

   Put weather stripping on the doors or door between your shop and the rest of the basement. Seal electrical outlets that may be on common walls between the two. Blank off any supply registers that might be supplying air from the heating system to the shop. Install an exhaust fan in an exterior window in the shop to ensure that all air that exits the shop is expelled outdoors rather than recirculated into the house. This will be at the expense of your heating bill, of course but the alternative doesn't seem much more attractive.

   Ideally, if you have an outside entrance to the shop, I'd go so far as to wall off the door between the basement and the shop. I think if you can effectively isolate the shop from the rest of the house you can all but eliminate the airborne dust problem.

   ...........
   From Beautiful Skagit Co. Wa.
   Dennis
1. 
   MarkRD | Mar 12, 2005 08:31pm | #13

   I don't know about heat pumps, I'm assuming that there is no carbon monoxide issue otherwise the Negative pressure idea would be a bad thingMark
   

   Measure it with a micrometer, mark it with chalk, cut it with an ax.

1. 
   DennisS | Mar 13, 2005 09:06am | #17

   Mark -The heat pumps that I'm familiar with have all the working machinery outdoors. The compressor and evaporator and .... stuff. And around here they all run on electricity. There's a heat exchanger located somewhere indoors that transfers the heated media to the air in the forced air system.Most forced air systems (again that I'm familiar with) have a central cold air return. In other words, conditioned air is supplied to every space/room in the house and it's recirculated through the house to the single return. My thinking is, that since the shop is located in a basement room, there may be a supply duct goint ~to~ the room which would put the room under postivie pressure. The exhaust, if you will, is through the door to the single return air inlet to the system.If indeed this is the case in the design of the system under discussion, it would seem prudent to eliminate the supply air to the shop that comes from the central HVAC system and create a separate system for the shop. Otherwise the conditions in the shop will be shared with the rest of the living spaces. Once this is accomplished, keeping the shop under negative pressure by exhausting air to the outdoors should thus eliminate any transfer of shop air to the rest of the house.Just speculation, of course, without knowing any particulars of the system design............
   From Beautiful Skagit Co. Wa.
   Dennis

1. 
   mvac | Mar 13, 2005 04:57pm | #18

   Dennis,

   Thanks for weighing in. Just to clarify, my problem isn't with dust getting into the rest of the house - it's with dust getting into the heat exchanger, specifically the coils, motor and fan, as well as some of the intake ducting in the shop that isn't completely sealed. This has made the lower heating zone highly inefficient. So, we're not only colder than we should be, we're paying a lot more for heat than we need to.

   Your thought about an exaust register in the room itself is intersting, though. One does exist in my shop, and if I understand you correctly, is it creating positive pressure which could contibute to forcing air into the exchanger? In other words, would closing the register help to solve the problem? (I doubt it would do it completely - I think sealing the  leaks in the ducting and around the filter in the heat exchanger, as well as getting the coil/fan/motor cleaned - are also necessary steps).

   What say you, sir?

   Thanks again,

   Mitch

   "I'm always humbled by how much I DON'T know..."

   Edited 3/13/2005 9:58 am ET by mvac

1. 
   DennisS | Mar 13, 2005 05:45pm | #19

   mvac-As I said, without a clearer picture of how your system is designed, air flow wise, I can only speculate. But my first focus would be on isolating the shop atmosphere from the rest of the house. If it means totally sealing any and all ducts from or to the heat exchanger that originate in the shop, then so be it. Tape plastic sheeting across the openings if necessary. If the shop is to be a permanent fixture in your house, I'd disconnect and seal the ducts to and from it if they're accessable.Do you have a separate entrance to the shop to the exterior? If you do, seal the door between the rest of the basement and the house. Even if it means having to go outside to get to the shop.Once you think you have the shop isolated, Try placing some sort of room deooderiser or some other method to introduce something into the air in the shop that you could identify by smell. Non toxic of course (grin). Something strong enough but not so obnoxious that you wouldn't mind smelling it throughout the house. Leave it in there for a bit while the system is running and see if you can detect the aroma anywhere else in the house. If you do, then the shop's not isolated.That handles the airborne dust that's being introduced into the duct system. Why and how the dust is getting on the outside of the ducts as shown in your pictures is another issue. That's where having a good strong box fan sitting in a window blowing the shop air to the exterior might be a solution. You'd probably want to filter the exhaust air so as not to coat the outside of your house with dust.Get the shop under negative pressure so all the shop air is being exhausted outdoors. Provide an intake for outside air at the other side of the shop so you're not exausting heat sucked in from the rest of the house. The exhaust fan should not be located anywhere near the compressor which I'm assuming is located outside the house. If you decide to get even a smallish dust collection system, install it outside the shop so what the filters, bag or cartridge, don't get will be outside and not in the shop. This will require something with enough power to handle the added ductwork, but considering the not so attractive alternatives, it would be worth it.The shop has to be totally isolated from the rest of the house in order to solve the airborne dust problem. In my opinion, at least............
   From Beautiful Skagit Co. Wa.
   Dennis

9. 
   VomSorb | Mar 16, 2005 01:25pm | #28

   Losing battle...

1. 
   mvac | Mar 16, 2005 02:59pm | #29

   Tell me about it...Mitch

   "I'm always humbled by how much I DON'T know..."