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#1
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Furnace filter doesn't filter?
Due to allergy I installed a filter cabinet and a merv 12 4-inch filter in
my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? |
#2
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Furnace filter doesn't filter?
On Jan 1, 11:06*am, "bob" wrote:
Due to allergy I installed a filter cabinet and a merv 12 *4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? Possibly dirt that is already in the heating ducts from before you put the MERV filter in the system? |
#3
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Furnace filter doesn't filter?
On Sun, 1 Jan 2012 08:06:54 -0800, "bob" wrote:
Due to allergy I installed a filter cabinet and a merv 12 4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? *Some* dust is normal. Places it comes from and where you might want to check. . . Did you clean or replace the ductwork when you installed the expensive filter. [I'm guessing that a 'merv 12 4-inch' filter is expensive-- I don't know anyhting about them] I'd replace it myself if you're up to the task. Buy a good respirator before you begin. You won't believe how much crap accumulates in a decade or two. Did you at least check all the ductwork for points of infiltration? The air gets filtered at the furnace. if there is a pinhole in a duct it will suck dirt out of whatever cavity it happens to be in. that's why some folks put filters on the registers. Jim |
#4
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Furnace filter doesn't filter?
"bob" wrote in message ... Due to allergy I installed a filter cabinet and a merv 12 4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? When did you last have your ducts cleaned out ? You might want to have a closer look at those dust particles under magnification to have a better idea of their source. |
#5
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Furnace filter doesn't filter?
On Jan 1, 11:06 am, "bob" wrote:
Due to allergy I installed a filter cabinet and a merv 12 4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? Possibly dirt that is already in the heating ducts from before you put the MERV filter in the system? I forgot to mention I had the ducts cleaned (vacuumed) by the same company who installed the filter cabinet, which is 3 months ago. They commented the ducts were very clean already. The ducts have also been sealed 2 or 3 years ago, and although it is not 100% sealed, the contractor performed a blower door test and said it was acceptably sealed. The reason I say it is not 100% sealed is because during the summer, I can smell a faint crawlspace odor coming out of the register when I'm in the bathroom with the ventilation fan on. The furnace is about 5 years old. The 4 inch filter is filtrete brand and cost $30 or so at hardware store. I will set up a carbon monoxide alarm next to the register just in case. Are there "serious" air filter for floor registers with merv ratings like the furnace filters? I see foam-like filter that fits inside the floor register, but they have no ratings. |
#6
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Furnace filter doesn't filter?
On 1/1/2012 3:06 PM, bob wrote:
On Jan 1, 11:06 am, "bob" wrote: Due to allergy I installed a filter cabinet and a merv 12 4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? Possibly dirt that is already in the heating ducts from before you put the MERV filter in the system? I forgot to mention I had the ducts cleaned (vacuumed) by the same company who installed the filter cabinet, which is 3 months ago. They commented the ducts were very clean already. The ducts have also been sealed 2 or 3 years ago, and although it is not 100% sealed, the contractor performed a blower door test and said it was acceptably sealed. The reason I say it is not 100% sealed is because during the summer, I can smell a faint crawlspace odor coming out of the register when I'm in the bathroom with the ventilation fan on. The furnace is about 5 years old. The 4 inch filter is filtrete brand and cost $30 or so at hardware store. I will set up a carbon monoxide alarm next to the register just in case. Are there "serious" air filter for floor registers with merv ratings like the furnace filters? I see foam-like filter that fits inside the floor register, but they have no ratings. Help us a little. What does your furnace use for fuel? Filters usually don't fit tightly in the holder. Did you somehow seal up around the edges of the filter? Do you have little critters chewing into the heating vents, or the cold air return ducts? Perhaps you are smelling them. Get some "man sized" cleneex and wrap one or two of these under a floor register. After a week, remove and examine for dust or whatever. Should be clean if your filter is doing it's job. They are for collecting evidence, not for regular air filtering. Paul |
#7
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Furnace filter doesn't filter?
On Jan 1, 1:59*pm, "
wrote: On Jan 1, 1:35*pm, Evan wrote: On Jan 1, 11:06*am, "bob" wrote: Due to allergy I installed a filter cabinet and a merv 12 *4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? It is the dirt built up in your duct work from before you installed the filtration system... You should have your duct work cleaned, pressure tested and properly sealed at each connection point and then insulated... Less dirt in your air with the filter, none can get sucked in at the joints in the duct work The portion of the system AFTER the filter he just installed has positive pressue. *Nothing is being sucked into it. *On the other hand, the vacuum in your empty skull, I;m not so sure about Evan, clueless as usual Too bad with the reduced ozone layer in the polar regions you Canadians are exposed to more extra terrestrial radiation... I assure you mr canadian that crap builds up in ductwork under positive pressure, with the right amount of moisture things like to grow too... And you clearly aren't aware that positively pressurized duct work creates suction and aspirates when the fans cycle off if they are not well sealed... But the OP has replied with more info since... ~~ Evan |
#8
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Furnace filter doesn't filter?
MERV stands for Minimum Efficincy Reporting Value. It's a scale from 1 to
16. A MERV of 12 is currently popular with the heating and AC industry for filters. It should do a pretty good job of stopping particles above 1 micron in size. Smaller particles will be less well impeded. Your dirt may be smaller particles. Why the focus on dirt? How's the allergy doing? That's the important thing, not dirt. Are you allergic to things that are bigger than 1 micron? Dave M. |
#9
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Furnace filter doesn't filter?
On Jan 1, 10:05*pm, Evan wrote:
On Jan 1, 1:59*pm, " wrote: On Jan 1, 1:35*pm, Evan wrote: On Jan 1, 11:06*am, "bob" wrote: Due to allergy I installed a filter cabinet and a merv 12 *4-inch filter in my furnace. I thought I'd be getting very clean air. To verify, I cover two floor registers with furnace filters. After a few weeks these filters turned dark grey and can be seen from either side of the filter. I flipped it over and there is no dust accumulation. Is this normal? Where do the dark fine particles come from? It is the dirt built up in your duct work from before you installed the filtration system... You should have your duct work cleaned, pressure tested and properly sealed at each connection point and then insulated... Less dirt in your air with the filter, none can get sucked in at the joints in the duct work The portion of the system AFTER the filter he just installed has positive pressue. *Nothing is being sucked into it. *On the other hand, the vacuum in your empty skull, I;m not so sure about Evan, clueless as usual Too bad with the reduced ozone layer in the polar regions you Canadians are exposed to more extra terrestrial radiation... Who dragged Canadians into this? I'm not Canadian, you;re just confused as usual. I assure you mr canadian that crap builds up in ductwork under positive pressure, with the right amount of moisture things like to grow too... Show us how dirt gets in with positive pressure. Enough dirt that it's showing up at the registers. And you clearly aren't aware that positively pressurized duct work creates suction and aspirates when the fans cycle off if they are not well sealed... Show us how dirt gets in with positive pressure. Enough dirt that it's showing up at the registers. But the OP has replied with more info since... And you're the guy who told us not too long ago that nitrogen had to be recovered from an AC system and not released into the atmosphere. And how you NEVER, EVER want to cut and re-glue a PVC exhaust pipe because everyone is gonna die and that requires special skills. Meanwhile every idiot around is installing dryers, for example. What a fool. |
#10
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You mentioned that the filters were black color. What type of furnace do you have? It could be possible smoke from the furnace if it's a pellet or wood burning furnace. Or even with a gas furnace, there could be a residue like grease that is burning.
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