Home |
Search |
Today's Posts |
|
Home Repair (alt.home.repair) For all homeowners and DIYers with many experienced tradesmen. Solve your toughest home fix-it problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
|
#1
|
|||
|
|||
furnace filter efficiency impact
I've read in many places that you should change your furnace filter
regularly as a dirty filter will lower the efficiency of your furnace. Excluding extreme cases where a filter is exceptionally dirty, how much of a loss in efficiency are we talking about for the average "needs to be changed in the next couple of months" filter? PS: I'm not trying to find a reason to stop changing my furnace filters or anything. I'm simply curious as to how much impact a dirty filter can have. Is it 0.1 - 2% or more like 10%? |
#2
|
|||
|
|||
I've read in many places that you should change your furnace filter
regularly as a dirty filter will lower the efficiency of your furnace. Excluding extreme cases where a filter is exceptionally dirty, how much of a loss in efficiency are we talking about for the average "needs to be changed in the next couple of months" filter? PS: I'm not trying to find a reason to stop changing my furnace filters or anything. I'm simply curious as to how much impact a dirty filter can have. Is it 0.1 - 2% or more like 10%? I don't have a number for you, but you may want to cosider this. If your filter is blocked, then less air is being fed into the furnace by the cold air return ducts. If you don't have a perfectly sealed furnace chamber, then the furnace might be drawing some of it's air from your basement, which might be pulling air from the first floor dwn to the basement. This might increase the mold growth in your basement (i.e. bringing relatively warm moist air into the cold basement). Just a thought. |
#3
|
|||
|
|||
Jonny R wrote:
I've read in many places that you should change your furnace filter regularly as a dirty filter will lower the efficiency of your furnace. Excluding extreme cases where a filter is exceptionally dirty, how much of a loss in efficiency are we talking about for the average "needs to be changed in the next couple of months" filter? PS: I'm not trying to find a reason to stop changing my furnace filters or anything. I'm simply curious as to how much impact a dirty filter can have. Is it 0.1 - 2% or more like 10%? Hi, Why don't you experiment yourself? I saw a clogged up filter bringing down room temp. to near freezing point in dead winter. No kidding. When I took the filter out, it looked/felt like a black sheet of slate. Tony |
#4
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
replying to Jonny R, Iggy wrote:
Just so any passersby have a little more answer. In my own testing I found no difference on my electric bill ("efficiency" is only based on the blower motor or air movement, in this case) when I went to annual and now even every 2-years of a change out...I used to smoke and no longer do. I would've expected 10%, but I saw nothing when I had to wait 2-months after moving-in for a custom filter size. The old filter's corrugations were completely filled and the filter face was flat smooth with dust. I put the new filter in and saw no difference on my bill and heard no relief from the blower motor nor ductwork. My findings agreed with the basic recommendation. If you can't see through the filter when held up to the Sun or bright light, then and only then it should be changed. Regardless of that, a new filter should go in after carpeting has been changed out or after a dusty home improvement...so yuck doesn't sneak by and into the HVAC system or your air. I also found that high MERV ratings didn't effect my efficiency at all either. So, I went with 3M's Ultra Allergen filters, even though they're almost twice the MERV rating warned against by the HVAC manufacturer. They've kept my system like new and dustless for a full 10-years now. -- for full context, visit https://www.homeownershub.com/mainte...ct-565075-.htm |
#5
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
On Monday, September 4, 2017 at 5:14:10 PM UTC-4, Iggy wrote:
replying to Jonny R, Iggy wrote: Just so any passersby have a little more answer. In my own testing I found no difference on my electric bill ("efficiency" is only based on the blower motor or air movement, in this case) when I went to annual and now even every 2-years of a change out...I used to smoke and no longer do. I would've expected 10%, but I saw nothing when I had to wait 2-months after moving-in for a custom filter size. The old filter's corrugations were completely filled and the filter face was flat smooth with dust. I put the new filter in and saw no difference on my bill and heard no relief from the blower motor nor ductwork. My findings agreed with the basic recommendation. If you can't see through the filter when held up to the Sun or bright light, then and only then it should be changed. That test would seem to depend on what kind of filter you have, if at all. Filters range from the cheap fiberglass ones that are less than an inch thick to 5" thick pleated ones that have a high MERV rating. The latter, you can't see through when they are brand new. I agree that with any filter you'd have to block it up a substantial amount, raise the pressure drop significantly for it to have any significant effect on efficiency. |
#6
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
replying to trader_4, Iggy wrote:
Yeah, I assumed a 1" filter and not a fat-boy or electrical. I'd suspect a lot of pet hair, drywall dust or sawdust would have a big effect and likely stop air movement even entirely. In my case it seemed to be just a collection of regular light and loose dust and pollen that may have actually helped to filter new particles. Though, I was surprised the MERV rating didn't show up as an efficiency drop. -- for full context, visit https://www.homeownershub.com/mainte...ct-565075-.htm |
#7
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
The purpose of the filter is to protect your coils or heat exchanger, not to clean the air for humans.
It seems reasonable to me that a dirty filter will catch more dust than a clean filter and be better for your coils, up until the point it impedes air flow. |
#8
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
On Tuesday, September 5, 2017 at 8:20:04 AM UTC-4, TimR wrote:
The purpose of the filter is to protect your coils or heat exchanger, not to clean the air for humans. It seems reasonable to me that a dirty filter will catch more dust than a clean filter and be better for your coils, up until the point it impedes air flow. yeah i agree, and if you keep a thermometer in the duct to monitor the air temperature, if the air flow is significantly impeded, the air temperate will rise in the heating season or drop in the cooling season. If the duct air temp is normal , the air flow is normal. m |
#9
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
On Tuesday, September 5, 2017 at 8:20:04 AM UTC-4, TimR wrote:
The purpose of the filter is to protect your coils or heat exchanger, not to clean the air for humans. Who made that determination? Sure, the cheap 1" fiberglass crap filters that are the minimum were likely put there back in the early days to protect the eqpt. But today there are advanced filters available, from 5" thick high MERV to electrostatic that go way beyond what is needed to protect the eqpt. And they are sold and markteted to clean the air for humans. It seems reasonable to me that a dirty filter will catch more dust than a clean filter and be better for your coils, up until the point it impedes air flow. Any filter, as it clogs, will start to impede air flow, raising the pressure drop. I think we agree that it won't affect efficiency until it's substantial enough to cause a significant pressure drop. |
#10
Posted to alt.home.repair
|
|||
|
|||
furnace filter efficiency impact
On Tue, 5 Sep 2017 05:19:56 -0700 (PDT), TimR
wrote: The purpose of the filter is to protect your coils or heat exchanger, not to clean the air for humans. It seems reasonable to me that a dirty filter will catch more dust than a clean filter and be better for your coils, up until the point it impedes air flow. Which is just before it gets dirty enough for the extra dirt to improve filtration. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
High efficiency furnace - water out of outside pipe | Home Repair | |||
York Furnace Filter (High velocity)? | Home Ownership | |||
York Furnace Filter (High velocity)? | Home Repair | |||
Is it worth upgrading to High Efficiency furnace? | Home Repair |