Talk to me about air filters for my AC/Furnace

[O-gre 7]

I hear anything more than Merv8 and you put your whole system at risk. Please advise.

[alec.mc 180]

I hear anything more than Merv8 and you put your whole system at risk. Please advise.

personally I just use regular old 3m filters and change then when they need to.

 

A super restrictive filter can strain your fan,lower cfm and possibly freeze your coil if the air flow is low enough

[silverado427 10,716]

 I buy the 3 packs and change them every three weeks,  when the airs on. I use the pleated filters

[checko 180]

It depends on if anyone has any allergies in your home.  Like alec said if you get a very restrictive filter it can reduce the air flow greatly.  But if you have someone with severe allergies it really sucks to buy the crappy $3 filters and have all that crap blowing out of your ducts.  

 

3m has 3 levels. Red, purple, and blue.  Least to highest restrictive.   

 

I buy the red filtrete 2 packs. 

[M1152 713]

I hear anything more than Merv8 and you put your whole system at risk. Please advise.

you are probably OK with Merv8 on newer system, 8's are right in the middle, take a look here I'm using Merv12's. I change them out every 2.5 to 3 months

[DSD1026 48]

I buy the red filtrete 2 packs. 

This..  i buy the same. I also change them out every 2-3 months..  my thermostat has a little reminder when its time to change them..

[Jon 264]

AC/Heat newb... are you guys talking about the thin 1" thick filters? When I got my new HVAC installed the installer said I only needed to change the filter once per year. I have the 4 or 5" thick filters(don't recall exactly which size).

[tony357 386]

we use to not be able to use anything finer than 300, when the new heater and ac was installed we made the air intake box larger and we can use 800's now and change them out every 3 weeks..

[djg0770 481]

I hear anything more than Merv8 and you put your whole system at risk. Please advise.

 

Not enough information to determine the correct application for your system.

 

Is your system 40 yrs old and was originally designed for the filters that would only catch a mouse?  Is your system brand new?

 

Filters impose a pressure drop on your fan.  Pressure drop and airflow are directly proportional.  If you increase your pressure drop you lower your airflow (normally measured in cubic feet per minute (cfm)).  High merv filters will impose a higher pressure drop on your system. 

 

(Engineering goobledy-gook below, stop reading if you're not Asian )

If you lower your airflow too much your temperature change across your coil (delta T) increases due to the simple equation Q=1.085*cfm*delta T where Q = heat in BTU/h and cfm is airflow and delta T is the difference between the temperature entering and leaving the coil.  The Q of the coil is (almost/theoretically) the same so you can see if you increase your CFM your delta T across the coil drops and if you decrease your CFM your delta T across the coil increases.  Basically if you lower your airflow enough your leaving air temperature drops to the point that you can easily freeze the coil.  Freezing the coil is bad because air does not flow through ice very well.

[Howard 538]

I forget the name of my filters but they are pleated material.  Each section is about 4" deep and there must be about 40 or 50 of these sections.  They work great and only need to be replaced about once a year.

[O-gre 7]

_{11 year old system, 4000 sq ft. 2 units.}

[alec.mc 180]

_{11 year old system, 4000 sq ft. 2 units.}

 

 

If it aint broke.... Dont fix it.

 

I would however make an attempt to clean out your condenser coils ( outside unit ) and at least inspect your evap coil, and clean if need be.

 

Cleaning off 11 years of crud and debris could breathe new life into your system if its not cooling 100%

[ryan_j 0]

I only changed the filter last year after we had owned the house like 5 years. I should have figured when the filters were being sucked up in the return vent. It was coated with dust bunnies. I even think our electric bill went down a few bucks afterwards, LOL

 

That reminds me, the filter is due for a change. 

[silverado427 10,716]

If you have a dog or any pets you should clean your coil at least every other year. You would be amazed at how much colder your air gets. jmho.

[10X 3,296]

Lotta fussin' here over dust and dander and pollen.

 

How many of you wear a dust mask and latex gloves when reloading or at an indoor range?  

 

(I don't; I'm just suggesting that our beloved hobby probably poses a greater environmental exposure risk than having the wrong filter on the AC unit.) 

[Jon 264]

How many of you wear a dust mask and latex gloves when reloading

 

[checko 180]

Lotta fussin' here over dust and dander and pollen.

 

How many of you wear a dust mask and latex gloves when reloading or at an indoor range?  

 

(I don't; I'm just suggesting that our beloved hobby probably poses a greater environmental exposure risk than having the wrong filter on the AC unit

I'll guess that you don't have any people or pets in your house with severe allergies?

[Shawnmoore81 623]

I change the filter every 6 months and get it serviced yearly

 

 

Sent from my iPad using Tapatalk HD

[ryan_j 0]

Lotta fussin' here over dust and dander and pollen.

 

How many of you wear a dust mask and latex gloves when reloading or at an indoor range?  

 

(I don't; I'm just suggesting that our beloved hobby probably poses a greater environmental exposure risk than having the wrong filter on the AC unit.) 

 

In my case I want the system to run better and save energy/money. 

[silverado427 10,716]

I'll guess that you don't have any people or pets in your house with severe allergies?

I have a stand alone whole house air purifier eco quest ( at breeze ) 

[O-gre 7]

It's the difference between spending $15,000 a year from now or 10 years from now!

[TJ 4 the Boxers 0]

3 things that will clog the filter quickly are smoking, pets and how "dusty" the house is over all. I lived in place above a pizza shop and if I dusted in the morning, it didn't look like I did the next morning.

For those with older systems or just want to "cheat", spray your filter with a non flavored cooking spray like Pam (store brands are fine). You'll change your filter more often but the oil will collect more of the unwanted. If you use a scented one keep in mind your entire home will smell of that scent

As already stated clean the coils cause once the air flow is restricted you're in trouble. Think about how well you can breath with a plastic bag over your head.

[Dr Bocci 0]

So you are saying I pulled the pin out of the grenade by getting the merv 13 for my 20 year old system?