You are right that they are providing no filtration. Switch to the pleated disposables. They normally don't last for 3 months as advertized.
When they are covered with dust, change them. If you can't see light through them, you've waited too long.
How dirty should a filter be when it's changed - I change every 2-3 months?
I use the cheap blue disposable fiberglass filters and there are a few very small dustballs on the filters but otherwise it does not look dirty at all. I switched to the disposable filters because when I used the washable fiberglass or hogshair filters in the past, there was very little dust on those so I thought I wasn't getting enough filtration. But now I wonder if the disposable filters are providing any filtration.
I'm afraid to move up to the pleated filters - I don't see how air moves through those things.
You are right that they are providing no filtration. Switch to the pleated disposables. They normally don't last for 3 months as advertized.
When they are covered with dust, change them. If you can't see light through them, you've waited too long.
With the filters you are using ,the best filter in the system,is the "wet" coil.Look at Merv 8 or 10 ,4 or5" thick pleated filters.
I'm sure you have no clue what the airflow situation is for your system Joe. As such you should think twice before putting in a high efficiency filter. High efficiency is a code word for restrictive. Look at the paper filter and then look at the fiberglass. You can almost see through the fiberglass. The fiberglass breathes much better. Most duct systems are undersized and dont allow enough air to flow. Put in a high efficiency filter and you could be making a bad situation worse.
The fiberglass filters are more than adequate to protect the system if installed correctly (no air bypassing, etc.). Most furnace manufacturers provide filters with their furnaces that are similar in efficiency to fiberglass. If fiberglass weren't good enough then I don't think the OEMs would be providing similar efficiency filters with their units. I like higher efficiency filters as much as the next guy. But a system must be designed with them in mind or the airflow will suffer. Cookie cutter and even most custom homes virtually never have duct systems designed to handle high efficiency filters. Adequate airflow is much more important than the mostly placebo effect provided by high efficiency filters.
As far as the amount of dirt on the filter goes, it's not uncommon for some homes to see very little dirt accumulate. If your return (suction, intake, etc.) vent is high on the wall or ceiling then it may not be getting that much dirt. Dirt tends to hang low. Floor returns will dirty up the filter many times faster.
Fiberglass filters in my home work. Evap coil cleaned annually and not much comes off.
It all depends on your particular duct design and filtering desire. The air velocity is low enough at my filter that the fiberglass filters do a fine job. Of course, I'm just protecting the equipment. I'm not trying to capture every dust and pollen particle.
If a system has a ducted return,a lot of "stuff' will collect there before getting to the coil.
If the return grilles are in the ceiling ,a lot settles in the home,before getting to the filter.
If you have a furnace,a lot of stuff collects on the blower whell,before getting to the coil,not true with an air handler.
If you vacuum a lot ,with a cheap vacuum cleaner,more small particles will get into the system.
Lanced fin coils ,will collect more stuff.
Fins are spaced closer on newer coils,then older ones.
Lots of variables,and a merv 8 or 10 ,will handle keeping th coil cleaner longer,saving energy in the process.
Looking at a coil,is not a good way to tell if it's PD has increased increased .If you are not testing the PD of the coil ,compared to factory specs or previous results ,you really don't know if the coil is restricting the air flow.
Some manufacturers now sell and recommend,pleated filters.They also built coil with fixed metering devices,does that mean they never thought a TXV is a better way??
Thanks for all the replies.
Had a thought - what exactly (or roughly) equals "one month" in filter usage time. Is it 30 days x 24 hours?
I just realized we have had a mild May/June here in Ga so the a/c only runs 6-7 hours a day (we turn it off when going to bed and don't turn it back on until mid afternoon). The filter has been in since March (got a little bit of time in during the heating season) but we barely ran the system during the spring.
BTW - I do have floor returns on the first floor but it's mostly wood floors (don't know if that increases or decreases dirt into the system but a few of the return grills have dust on them). Upstairs the returns are in the ceiling so that might explain why the upstairs filters are clean.
Originally posted by joeyjoey
BTW - I do have floor returns on the first floor but it's mostly wood floors (don't know if that increases or decreases dirt into the system but a few of the return grills have dust on them). Upstairs the returns are in the ceiling so that might explain why the upstairs filters are clean.
Exactly.
If you can see thru it, dirt can go thru it.IMO, put in a pleated type at the very east.
Of course , we live in rural farm and ranch country... lots of "dust" Maybe you city boys don't have that problem ??
Life goes on long after the thrill of living is gone.
There's better and there's adequate Dash. In the case of a TXV the TXV doesn't cause other problems. It's only better while the fixed metering device can be adequate. In the case of filters though better can cause airflow problems. And since airflow problems are rampant, one must assume that a better filter will worsen the problem until a pro can analyze the situation to know that it won't worsen the problem.
I have no problem with better filters. In farm country they're almost mandatory. But to blindly recommend them to all that come on this board is folly. I'm not saying that you are blindly recommending them. But I sure as sh** haven't seen anything else... yet.
Sure as ---- ,I think they are needed.
If mfrs. were worried about keeping coils clean ,and airflow up to the required cfms,why do the include cheap filters that you can see thru??
Dopes air flow need to be addressed ,absolutly!!!!That's what HVAC contractors should be able to do !!!!
[Edited by dash on 06-27-2005 at 09:55 AM]
Because they know that in most applications the see through filters are perfectly adequate for the equipment's sake.Originally posted by dash
If mfrs. were worried about keeping coils clean ,and airflow up to the required cfms,why do the include cheap filters that you can see thru?
A great analogy is the much hyped 3000 mile oil change. It's purely an invention of the oil industry. Few cars need their oil changed that often. GM's oil light system often goes off at five to seven thousand miles. Mercedes' OLS can go ten to twenty thousand miles before going off. The 3,000 mile fallacy has been pushed to sell oil and service.
The same goes for filters. The move towards better filters in the retail segment is largely the result of a desire for higher revenues. My local Home Depot has a wide variety of expensive filters at ground level. They've got a hit and miss selection of fiberglass sitting up high. At one to two dollars a pop versus five to fifteen bucks a pop, there's little question as to why. And it's not because it helps the equipment. Given how starved most HVAC equipment is for air they do their customers a disservice.
But at least with the oil change no harm is being done. The same can't be said of high efficiency filters.
Yes,Home Depot and the mfrs of filters are doing a disservice to consumers ,by not warning about the possible effects on air flow.
I'm advocating that consumers should get "better" filtration,from a contractor that can design or redesign the ducts ,as needed to insure proper air flow.
TXv's installed "helter-skelter",like high PD filters ,do cause damage.LOL!
>>TXv's installed "helter-skelter",like high PD filters ,do cause damage.
Dash, could you offer a one or two-sentence explanation of how a TXV might cause damage? How much should a homeowner concern himself with this possibility? Until now I had heard only good things about this device, am interested in knowing the other side of the story.
Best wishes -- P.Student
I'm afraid another post by someone else has been taken on an excursion.
ANYTHING installed "Helter-Skelter" can do damage.
Irascible described TXV'S in comparison to piston as a way of showing better and good in an attempt to show that the cheaper filters are doing what the manufacturer intends.
And he's right.
I have no argument with that.Originally posted by dash
I'm advocating that consumers should get "better" filtration from a contractor that can design or redesign the ducts as needed to insure proper air flow.
I'd love to see the study or data that convinced you a wet coil filters better than a fiberglass filter. It seems to be the basis for a lot of your recommendations. Yet in my mind it's clearly false. A fiberglass filter will get caked over and over while the coil gets barely a tinge of dirt. But you say it catches more? Pfft.
I use the cheap pleated filters that Wal Mart sells for $1.88. I won't use fiberglass as I consider then to be worthless. I won't use the expensive pleated filters because they are a waste of money, and might reduce air flow.
Yes, hardwood floors = more dirt because it can't absorb the dirt like a carpet can. I never saw dust tumbleweed until I moved someplace with hardwood floors.
The last I checked a cheap pleated and 3M's pleated had similar pressure drops. The supposed difference in the 3M is that how it's made causes it to have an electrostatic charge. If you don't know your airflow situation and how the pleated is affecting it, then the pleated may be worth less and the fiberglass worth more than you think.
Note the "LOL" after the my TXV example.Originally posted by perpetual_student
>>TXv's installed "helter-skelter",like high PD filters ,do cause damage.
Dash, could you offer a one or two-sentence explanation of how a TXV might cause damage? How much should a homeowner concern himself with this possibility? Until now I had heard only good things about this device, am interested in knowing the other side of the story.
Best wishes -- P.Student
I was just trying to make it clear that ,if the ducts are sized correctly,a "better" filter will do no damage ,just as a TXV ,properly installed will "do no damage".
So the question is ,are "better" filters ,needed to protect the coil.My experience tells me they are.
The "wet coils are equal to a merv 5 or 6" came from an ACCA session at the National Meeting,the speaker was Brendan Reid,if I remember correctly.
I think he's with Comfort Institute,in Canada.