Furnace Filters

Warstud

Warstud

Joined
Sep 2, 2005
Messages
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Location
MIchigan
I just bought a 3M Filtrete Furnace Filter that has a Merv rating of 5 for dust and lint. Is it necessary to have a filter with a higher Merv rating in the winter since the air is cleaner.
 
You need to be careful when switching to Marv rating filter since the vast majority of ducks are undersized. To do it safely you need to check the air flow and if needed adjust it.
 
you really just want a rockcatcher. If you want to filter your home air.. use a device for that.
your furnace isnt a whole home air purifier.. and if it is.. its costing you $$$

I buy the cheapest decent filter that is pleated..
right now thats HDX 3 for 10$ at home depot.
Do not confuse Merv with FPR
but these are FPR 5
www.homedepot.com

HDX 16 in. x 25 in. x 1 in. Standard Pleated Furnace Air Filter FPR 5, MERV 8 (3-Pack) HDX3P5-011625 - The Home Depot

HDX filters are constructed of a durable, moisture-resistant frame with wire supported media for strength and rigidity. The wire-backed Pleated media offers a large surface area which increases the filter's
www.homedepot.com
LazyDog said:
You need to be careful when switching to Marv rating filter since the vast majority of ducks are undersized. To do it safely you need to check the air flow and if needed adjust it.
Click to expand...
hes talking about using a filter with a lower rating.. not higher so it should be less restrictive.

also its MERV and Duct ;)
 
Typically during the heating months there is more dust . Less humidity in ducts , dust is loose and flys out easily .
I think (they) say 11 Merv is a good air filter number .
 
Rand said:
you really just want a rockcatcher. If you want to filter your home air.. use a device for that.
your furnace isnt a whole home air purifier.. and if it is.. its costing you $$$

I buy the cheapest decent filter that is pleated..
right now thats HDX 3 for 10$ at home depot.
Do not confuse Merv with FPR
but these are FPR 5
www.homedepot.com

HDX 16 in. x 25 in. x 1 in. Standard Pleated Furnace Air Filter FPR 5, MERV 8 (3-Pack) HDX3P5-011625 - The Home Depot

HDX filters are constructed of a durable, moisture-resistant frame with wire supported media for strength and rigidity. The wire-backed Pleated media offers a large surface area which increases the filter's
www.homedepot.com

hes talking about using a filter with a lower rating.. not higher so it should be less restrictive.

also its MERV and Duct ;)
Click to expand...
The weird thing is one of Filtretes higher end filters… 3M’s MERV 13/1900 filter has a lower rated pressure drop than their lower end rock catchers.

HVAC Filters

I went down a bit of a rabbit hole today. Many HVAC techs I know and trust (friends and family, some with 60-70+ years in this field!), have always told me a MERV 5-7 cheap pleated filter was the way to go. The hog-hair filters let too much dust hit the coils of the HVAC system, and the MERV...
bobistheoilguy.com
 
Skippy722 said:
The weird thing is one of Filtretes higher end filters… 3M’s MERV 13/1900 filter has a lower rated pressure drop than their lower end rock catchers.

HVAC Filters

I went down a bit of a rabbit hole today. Many HVAC techs I know and trust (friends and family, some with 60-70+ years in this field!), have always told me a MERV 5-7 cheap pleated filter was the way to go. The hog-hair filters let too much dust hit the coils of the HVAC system, and the MERV...
bobistheoilguy.com
Click to expand...
Thats really interesting I need to check up on that. Thanks for the heads up
 
I use a filter of a MERV rating of 6 or lower. It is much easier on the motor and get good air flow. I change them every 30 to 40 days...Many HVAC companies reccomend a 7 or below MERV number....
 
LazyDog said:
You need to be careful when switching to Marv rating filter since the vast majority of ducks are undersized. To do it safely you need to check the air flow and if needed adjust it.
Click to expand...
Why??? The Merv rating has to do with the air flow through the filter....7 or below allows a good air flow...
 
nickaluch said:
Thats really interesting I need to check up on that. Thanks for the heads up
Click to expand...
Filtrete puts the pressure drops on the filters, I was surprised after reading that study and the 1900’s really are lower than the lower merv ones.
hrv said:
Why??? The Merv rating has to do with the air flow through the filter....7 or below allows a good air flow...
Click to expand...
Not necessarily, as I described above sometimes the higher MERV filters offer less pressure drop… probably because they have far more pleats.
 
Skippy722 said:
The weird thing is one of Filtretes higher end filters… 3M’s MERV 13/1900 filter has a lower rated pressure drop than their lower end rock catchers.

HVAC Filters

I went down a bit of a rabbit hole today. Many HVAC techs I know and trust (friends and family, some with 60-70+ years in this field!), have always told me a MERV 5-7 cheap pleated filter was the way to go. The hog-hair filters let too much dust hit the coils of the HVAC system, and the MERV...
bobistheoilguy.com
Click to expand...
I just got a 2-pack of red Filtrete 1085/MERV 11 filters at Lowe's. I noticed that the filters with higher ratings--purple 1500 and blue 1900-- had more pleats than the type I bought. I was going to say maybe that affects the pressure drop, but you beat me to it.
 
Rand said:
I buy the cheapest decent filter that is pleated..
Click to expand...
That's what my HVAC guy told me during a service call in the middle of winter when we had no heat. I bought some nice, thick, extra-filtering filters that restricted the airflow so much it kicked out the limit switch on the furnace. He said buy the cheap filters and change them every 30 days.
 
Being in Florida our HVAC system runs for a good percentage of the day especially in the summer months. So there is a good amount of change over in my home which obviously is important if you want your furnace filter to filter!

There have been many studies on in home air quality. One study pointed to Merv 11-13 being the sweet spot.

MERV ratings does not at all indicate airflow, the better filters add more pleats to compensate making this a non-issue.

I personally purchase MERV 12 filters. Food for thought, I rented a townhome years ago that provided free rock catchers. I noticed after 2 months it still looked relatively brand new. I opted to install a MERV 11 filter and it was night and day difference on how much that filter captured.
 
You
thescreensavers said:
Being in Florida our HVAC system runs for a good percentage of the day especially in the summer months. So there is a good amount of change over in my home which obviously is important if you want your furnace filter to filter!

There have been many studies on in home air quality. One study pointed to Merv 11-13 being the sweet spot.

MERV ratings does not at all indicate airflow, the better filters add more pleats to compensate making this a non-issue.

I personally purchase MERV 12 filters. Door for thought, I rented years ago that provided free rock catchers but I noticed after 2 months it still looked relatively brand new. I opted to install a MERV 11 filter and it was night and day difference on how much that filter captured.
Click to expand...

I believe it. At my last home I tried different MERV ratings and you have less dust over a longer span of time with MERV 11 or higher.
 
xBa380 said:
I use a carbon 16x25x5" Merv 16 by Lennox on my furnace. Plenty of air flow, no issues. Pricey, but only replace once a year each Spring.
Click to expand...
Me too was standard equipment...
Just a bit bigger though.
Screenshot_20220111-215517(1).jpg
 
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