Furnace Filter Interval

What’s the consensus on purchasing 4 inch filters…big box or mail order? I have two furnaces, which for twenty years used a Honeywell electrostatic air cleaner that had washable filters and they worked great. When I updated both HVAC systems two years ago, the electrostatic air cleaners were on their way out, I opted for the replaceable 4 inch filters. I have been purchasing them from the big box store twice a year, but I believe mail order might be more cost and time effective...if they get delivered undamaged. I’m thinking of nordic pure with free shipping, anyone have experience with on-line filter ordering?
 
I change it when it looks dirty. I just use the basic cheap filters. Our ductwork is old and if you put a really efficient and restrictive filter in, then the system will start to pull air from where it can, like around all the ductwork joints that might have weakened over the years. People think putting in the dust and allergen filters is good but don't realize that those can cause more issues than help. Best to keep it simple. Now if you have a brand new system and the ductwork is sealed tight, then they might be ok. To me keeping fresh air flowing freely is best. Our unit went out after 25 years and the evaporator looked great. No major dirt build-up and that was running the cheap tumble weed catcher style filters.
 
This is one of several products that can be used to improve the efficiency of the cheap filters. I use MERV8 pleated type filters and change them every two months instead of three because I run my blower continuously. This spray makes the surface of cheap filters a bit "tacky" so they catch smaller particles.
Filter Spray
 
My pre-filter gets checked monthly then I use a fine 3M filter that gets changed every 3 months, then I wash the electrostatic filter when the 3M is changed. Filters are cheap furnaces are not.
 
We had a new HVAC system put in about 5 years ago. The technician said to use those cheap fiberglass filters you get at Walmart for ~$1. He said to set the filter reminder on the thermostat for 3 months and change it when it goes off. So it costs about ~$4 per year.

We used to use the heavy duty 3M filter. The tech said those were more of a gimick than anything and also hard on the blower motor with the resistance they provide. I agree with him as I had one that basically warped so bad I had to tear it to get it out.

Is that a 1" filter?

The filter is as much to protect your fan, condenser, and ductwork as it is your lungs.

Typically the AC condenser coil is in line with the furnace and its filter

The cheapie filters let tons of dust into both the condenser and the ductwork where its really hard to get out later and HVAC techs call the buildup over time a "coil sweater" that can be pulled off in large chunks.

Pay more for an efficient filter that flows well, or pay later to clean or even replace your components.
 
The 1" filter in a HVAC its designed to keep the coil clean, not the your home. If you want to keep the air in your home clean then you need to get one of the 5" media filter boxes installed and they can use a MERV 11 or 13 (depending on size of HVAC) filter.
 
Is that a 1" filter?

The filter is as much to protect your fan, condenser, and ductwork as it is your lungs.

Typically the AC condenser coil is in line with the furnace and its filter

The cheapie filters let tons of dust into both the condenser and the ductwork where its really hard to get out later and HVAC techs call the buildup over time a "coil sweater" that can be pulled off in large chunks.

Pay more for an efficient filter that flows well, or pay later to clean or even replace your components.


yes a 1" filter.
 
Is that a 1" filter?

The filter is as much to protect your fan, condenser, and ductwork as it is your lungs.

Typically the AC condenser coil is in line with the furnace and its filter

The cheapie filters let tons of dust into both the condenser and the ductwork where its really hard to get out later and HVAC techs call the buildup over time a "coil sweater" that can be pulled off in large chunks.

Pay more for an efficient filter that flows well, or pay later to clean or even replace your components.
I hate to be "that guy," but it's the evaporator coil that the filter protects. The condenser coil is on your outdoor unit.
 
My NEST thermostat tells me when they should be replaced. We have two HVAC units in our home and they are called out for replacement at different times, so it must be tracking usage in some fashion.

How often are you replacing your furnace filter, and why are you replacing at that interval?

I run a 1” NaturalAire Standard (MERV 8) and replace every 500 hours. The thermostat tracks run time and displays when it’s due, KISS method.
 
I hate to be "that guy," but it's the evaporator coil that the filter protects. The condenser coil is on your outdoor unit.

no prob!

sorry syntax error on my part - I alway call the outdoor piece the compressor. Probably erroneously.
Im not an HVAC guy- just a guy thats bought a bunch of Air conditioners.


UD
 
no prob!

sorry syntax error on my part - I alway call the outdoor piece the compressor. Probably erroneously.
Im not an HVAC guy- just a guy thats bought a bunch of Air conditioners.


UD
;) Understood, Dave. The outdoor unit is usually referred to as the "condenser unit." It does have a compressor in it. It also includes the condenser fan and condenser coil, along with a contactor and dual run capacitor. I'm pretty sure they knew what you meant, though.
 
;) Understood, Dave. The outdoor unit is usually referred to as the "condenser unit." It does have a compressor in it. It also includes the condenser fan and condenser coil, along with a contactor and dual run capacitor. I'm pretty sure they knew what you meant, though.

Thanks DB.

....oh... and capacitors....bought and upgraded a lot of capacitors, cleaned a lot of coils...
just about everything I ever had had a soft start/easy start/ hard start kit added to it

UD
 
About every 1.5 months. Lots of fine dust here in the farm belt. If I forget the intake duct behind the couch gets weezy sounding. That intake is about 2 feet from the filter location and can hear it though the intake duct.
 
My NEST thermostat tells me when they should be replaced. We have two HVAC units in our home and they are called out for replacement at different times, so it must be tracking usage in some fashion.
lol, your nest thermostat has no clue how dirty they are so it's little more than a guess. Even if it tracks running hours it has no idea how much or little airborne dust there is.
 
Higher MERV ratings are great, if you are worried about restriction then get a thicker filter. Not only will you get the great filtering ability but you'll also extend your intervals.

I never buy below MERV11
 
lol, your nest thermostat has no clue how dirty they are so it's little more than a guess. Even if it tracks running hours it has no idea how much or little airborne dust there is.
True, I have looked at the filter and put it back.
 
Since the A/C runs almost constantly this time of year, I change it at the beginning of the hot season (mid-April), again mid-summer (end of July). The furnace barely runs at all during the winter, so I leave July's filter in until Jan 1. 3 filters per year. 20x25x4 A/C guy told me to keep the restriction down, so I use the run-of-the-mill Honeywells.
 
I just removed, vacuumed, and reinstalled my fiberglass filter.

Same here....I never get to see my evap coil since it's up in the attic and a duct runs from my ceiling to it.....my filter is changed from my hallway ceiling. I purchased a BOAIRE filter and wash and vacuum it every 3 months....It's a big filter (approx. 28"X 20" IIRC)...It has paid for itself easily in the 10 years since I had the system installed. (my system is a Heil which is a Carrier brand....a 14 SEER outside unit with a variable speed air handler which pushes it to 16 SEER (giving me the tax credit at the time)....it's very economical to operate.
This is the first year I had an issue....I came home one hot day in July and the house was warm...the outside unit wasn't working....I tried to get the installer to come to service it but he had retired....so I went on Youtube....bought a 'capacitor' and a 'contactor'...installed both....and everything was fine again...
PS: My unit is AC only...no furnace...
 
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