IveGotWood Posted January 24, 2011 Report Share Posted January 24, 2011 I am currently helping my brother remodel his garage into a modest 550 sqft shop. Our current design has our dust collection unit housed in a small shed that is connected to the exterior of the garage with the dust running through the shop wall. We thought this would help reduce the noise and the amount of fine dust that would be recirculated into our shop. We thought this was pretty slick until we saw a clip TWW did for Powermatic's site where he said that this type of setup could pose potential problems if there was a hot water heater in the shop. The reasoning behind this was the dust collector would be pulling fresh air out and this air would not be replaced. This drop in pressure could pull fumes out of the hot water heater that would normally vent up and out. Has anyone else run in to this problem? Obviously a solution is to allow fresh air in by opening the garager door. However, we just spent over a month insulating the worksop so we could stay warm, so I really don't want to open the door every time I want to have dust collection. Thanks for your help! Quote Link to comment Share on other sites More sharing options...
Vic Posted January 24, 2011 Report Share Posted January 24, 2011 I am currently helping my brother remodel his garage into a modest 550 sqft shop. Our current design has our dust collection unit housed in a small shed that is connected to the exterior of the garage with the dust running through the shop wall. We thought this would help reduce the noise and the amount of fine dust that would be recirculated into our shop. We thought this was pretty slick until we saw a clip TWW did for Powermatic's site where he said that this type of setup could pose potential problems if there was a hot water heater in the shop. The reasoning behind this was the dust collector would be pulling fresh air out and this air would not be replaced. This drop in pressure could pull fumes out of the hot water heater that would normally vent up and out. Has anyone else run in to this problem? Obviously a solution is to allow fresh air in by opening the garager door. However, we just spent over a month insulating the worksop so we could stay warm, so I really don't want to open the door every time I want to have dust collection. Thanks for your help! Will, I'm an energy efficiency consultant by day, and can tell you that it is EXTREMELY dangerous to depressurize a house or room that houses a non-direct vent gas appliance. One thing you can do in this situation is frame a return from the room where you are housing the DC unit. I'll see if I can find the page I use to determine CFM pull to return sizing. An HVAC contractor should be able to help. You can use a filter to lessen the impact of sound. You can also use a wall cavity by placing the hole low on one wall and higher on the opposite side of that wall. 1 Quote Link to comment Share on other sites More sharing options...
rmac Posted January 24, 2011 Report Share Posted January 24, 2011 Vic, just to make sure, is it true that this situation would only be a problem with a gas water heater (or other appliance)? No worries with an electric heater, correct? -- Russ Quote Link to comment Share on other sites More sharing options...
ChetlovesMer Posted January 24, 2011 Report Share Posted January 24, 2011 Will, I'm an energy efficiency consultant by day, and can tell you that it is EXTREMELY dangerous to depressurize a house or room that houses a non-direct vent gas appliance. One thing you can do in this situation is frame a return from the room where you are housing the DC unit. I'll see if I can find the page I use to determine CFM pull to return sizing. An HVAC contractor should be able to help. You can use a filter to lessen the impact of sound. You can also use a wall cavity by placing the hole low on one wall and higher on the opposite side of that wall. Vic, Got a question for you. I once saw a system in which they put the filter inside the shop but the cyclone and the rest of the collector outside in an attached shed. The reason was explained to me as being three-fold. 1 - Keeps the heat in the shop. 2 - Filters the air of the shop. 3 - Eliminates a lot of noise, and put the dust can out next to the trash can... i.e. easy dumping. I imagine it would also help with this problem. Does that hold water? Quote Link to comment Share on other sites More sharing options...
Sac Posted January 24, 2011 Report Share Posted January 24, 2011 Vic, Got a question for you. I once saw a system in which they put the filter inside the shop but the cyclone and the rest of the collector outside in an attached shed. The reason was explained to me as being three-fold. 1 - Keeps the heat in the shop. 2 - Filters the air of the shop. 3 - Eliminates a lot of noise, and put the dust can out next to the trash can... i.e. easy dumping. I imagine it would also help with this problem. Does that hold water? Hey Chet, this is how I have my DC setup. I have a cyclone mounted in my garage and have the intake and return run through a wall in the shop. I will say that it does a few things. If you have a few blast gates open, it can filter some air, but you need to have enough gates open for it to suck up a decent amount of air. I really dont count on it for this purpose. Does it keep the heat in the shop, not sure cause I have no way of monitoring the heat loss of the air as it goes through the cold cyclone in the unheated garage. But it does do a decent job of circulating the air in the shop. As for the noise, the only noise that it eliminates is the sound of the cyclone itself. The return air make quite a bit of noise along with some of the cyclone noise coming through the return air hose. It was so loud in fact, that I got a muffler for it from Penn State Industries. I have a Penn State cyclone too. It made a noticeable difference. I used a sound meter on my Android and it measured it at about 80dB. Not bad. Hope this helps. Quote Link to comment Share on other sites More sharing options...
jimmykx250 Posted January 24, 2011 Report Share Posted January 24, 2011 I believe without an air return you will be creating a negative air pressure situtation. You need to make up the air you are pulling out somehow. Quote Link to comment Share on other sites More sharing options...
Vic Posted January 24, 2011 Report Share Posted January 24, 2011 Vic, just to make sure, is it true that this situation would only be a problem with a gas water heater (or other appliance)? No worries with an electric heater, correct? -- Russ Russ, It would be a hazard with any combustion situation. It would be detrimental in regards to energy usage (heating/cooling) in any scenario without the proper return flow. It's just never a good idea to depressurize a room or house. Pressure has to reach equilibrium. So, in this scenario, outside (unconditioned) air would be sucked in from every possible nook and cranny. In a house scenario, that can often be from the crawl space or attic, both of which don't typically have good air quality. Quote Link to comment Share on other sites More sharing options...
Vic Posted January 24, 2011 Report Share Posted January 24, 2011 Vic, Got a question for you. I once saw a system in which they put the filter inside the shop but the cyclone and the rest of the collector outside in an attached shed. The reason was explained to me as being three-fold. 1 - Keeps the heat in the shop. 2 - Filters the air of the shop. 3 - Eliminates a lot of noise, and put the dust can out next to the trash can... i.e. easy dumping. I imagine it would also help with this problem. Does that hold water? Response to question 1: To some extent, yes. Much depends on how well sealed the ducting is outside of the conditioned envelope and how much insulation is present to keep the heat in the ductwork. But, it is not better in this regard than having the unit completely inside the conditioned envelope. Also, still a significant combustion/back draft risk if it is not 100% air sealed. If you just do NOT want to live with the DC unit in the shop, my suggestion would be to house it in an adjacent conditioned space with adequate return ventilation to the shop. I'll defer to Sac's response on 2 & 3. I have an Oneida 3HP Dust Gorilla and it's not that loud, as I have it behind an insulated stub wall. The insulation is only to muffle noise. The noise isn't that bad compared to my power equipement, but I have not tested the db levels. Quote Link to comment Share on other sites More sharing options...
IveGotWood Posted January 24, 2011 Author Report Share Posted January 24, 2011 Vic, Thanks for your help. What kind of filter can I use on the return hole? I know that I am trying to keep out the fine dust particles, and my understanding is that I would need a filter that can get rid of particles down to around 1 or 2 microns. Do they make filters specifically for this purpose? Also, what is benefit of having a high and low hole? It makes sense to me that this would help with heat loss by not allowing heat to go "straight" through, but I wonder how this compares with the loss of heat by removing the insulation from that area. Thanks for your help, this is extremely helpful. Quote Link to comment Share on other sites More sharing options...
Vic Posted January 24, 2011 Report Share Posted January 24, 2011 Vic, Thanks for your help. What kind of filter can I use on the return hole? I know that I am trying to keep out the fine dust particles, and my understanding is that I would need a filter that can get rid of particles down to around 1 or 2 microns. Do they make filters specifically for this purpose? Also, what is benefit of having a high and low hole? It makes sense to me that this would help with heat loss by not allowing heat to go "straight" through, but I wonder how this compares with the loss of heat by removing the insulation from that area. Thanks for your help, this is extremely helpful. I'd get it through, either an HVAC warehouse or an HVAC contractor. You want a 2 inch return grill sized for your CFM situation. You can get good 2" pleated style filters from your local home center borg. Again, for the best sound deadening, either do a flex duct jumper in the attic from the DC room back to the shop, or stagger the holes in the sheetrock from one down near the floor and the other near the top of the stud bay on either side of the wall. Quote Link to comment Share on other sites More sharing options...
dlamulle Posted January 26, 2011 Report Share Posted January 26, 2011 Howdy, First I would say if you are in a shop area with no central air/heat and no gas hot water heater or dryer I can't see how you doing what you pointed out would have any other affect but to pull cold or hot air from under doors and such into your insulated space. All you are essentially doing is putting a huge high capacity window fan in and pulling air out of your space, np with that. If you do have central or gas then it is a problem so I've included some photo's of how I fixed it in my shop. I have included two photos of my shop and how I tackled the same situation. My shop has central heat/AC and the heat is gas. I have a 3hp DC that is located in an enclosure next to my shop but not included in the central unit area. I installed 2 vents from my shop to this area to allow the heated air to return to the shop from this area. I bought the vents from Lowe's which fit between the studs nicely and use the best AC filters I can find. You can see from the second photo the area with the DC. It also houses my air compressor and some other storage but is closed off from the main shop. This system has worked fine for 4 years and I have no noticeable heat or ac loss. I hope these help. Dave Quote Link to comment Share on other sites More sharing options...
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