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View Full Version : What MERV do i want?



Wade Lippman
11-17-2017, 10:13 PM
My furnace takes 16x25x5 filters.
1) Do I want merv11, merv13, or something else? (obviously the higher the better, but I am concerned about air flow)
2) Generic filters are $21. Honeywell filters are $35. Which is the better value.

I change filters twice a year. They claim they are good for year, but after 6 months mine are pretty dirty.

George Bokros
11-17-2017, 11:14 PM
I always go for MERV 13. I do not think air flow is an issue.

Jamie Buxton
11-17-2017, 11:19 PM
Your furnace takes in air from the house, heats it up, and sends it back to the house. If you have no filter at all in the furnace, the heated air is exactly as dirty as the other air in the house. So why do you need a filter?

George Bokros
11-18-2017, 8:15 AM
Your heat exchanger, and if you have AC your AC coil, will become coated with dirt and become less efficient in doing their job.

Perry Hilbert Jr
11-18-2017, 9:21 AM
Bokros< Are you single? So that the air being recirculated is not as dirty as the air in the house. Less dust landing on the furniture, computers and tv screen. We change filters three times a year. We also run an air cleaner to cut down on dust. We have three asthmatics in the house. It helps. Since the new house and air cleaners no hospital visits for asthma attacks.

Chris Damm
11-18-2017, 9:52 AM
I just had an energy assessment done by my local utility and they recommended MERV 8-10 and changing them no less than every other month. I had MERV 13 at the time. So far my wife hasn't noticed any increase in dust. The temps seem to be more balanced after changing to a less restrictive filter.

George Bokros
11-18-2017, 4:45 PM
Bokros< Are you single? So that the air being recirculated is not as dirty as the air in the house. Less dust landing on the furniture, computers and tv screen. We change filters three times a year. We also run an air cleaner to cut down on dust. We have three asthmatics in the house. It helps. Since the new house and air cleaners no hospital visits for asthma attacks.

What does this mean Perry -- Bokros< Are you single?

I have an Aprilaire pleated filter that is 4" thick and is supposed to be good for a year with the fan cycling and nine months with the fan running continuously. My fan runs continuously but the filter needs changed about every every 4 months which I do.

Perry Hilbert Jr
11-19-2017, 11:47 AM
George, your original post at 7:15 am yesterday made it sound as if you saw no use to using a filter because the air is just recirculated. Something a single guy might say or think. So in that contest, at 8:21 am I asked if you are single? You edited your post at 3:39 pm removing that language. And then asked my why I made that statement to your unedited early morning statement. Of course, after your edit, it makes no sense.

George Bokros
11-19-2017, 11:49 AM
George, your original post at 7:15 am yesterday made it sound as if you saw no use to using a filter because the air is just recirculated. Something a single guy might say or think. So in that contest, at 8:21 am I asked if you are single? You edited your post at 3:39 pm removing that language. And then asked my why I made that statement to your unedited early morning statement. Of course, after your edit, it makes no sense.

OK now it makes sense.

Prashun Patel
11-19-2017, 1:05 PM
I buy my no name filters online in 6 or 12 packs. Even the MERV 13s are economical that way. Also, having a bunch on hand makes it psychological easier for me to change them frequently.

my favorite Merv was Merv Griffin.

Jason Roehl
11-19-2017, 8:00 PM
Your furnace takes in air from the house, heats it up, and sends it back to the house. If you have no filter at all in the furnace, the heated air is exactly as dirty as the other air in the house. So why do you need a filter?


Are you serious?

First and foremost, the air is filtered before it goes through the furnace blower. A blower will collect dirt quickly and throw it out of balance, leading to premature motor and/or blower bearing failure.

Secondly, your sinuses and lungs will thank your for filtering your indoor air. Several years ago, I upgraded my thermostat to a Honeywell WiFi unit with the color touchscreen. One of the features is a "circulation" mode--which runs the HVAC fan periodically (maybe 15 minutes every hour). I have noticed we have FAR fewer allergy/cold/sinus issues in the five members of the household since I did this.

My furnace also takes up to 5" of filters. I use four 1" filters. The first is a washable unit (I keep a clean one on hand). The second is a cheap disposable. The third is a mid-grade filter, and the one closest to the furnace is a higher-dollar, allergen-rated filter. I swap out the washable one about every 3 months, the cheap disposable about every 6, and the other two roughly every year. Filters actually get BETTER at filtering the dirtier they get, though there is a point at which they are starving the blower. If they're deforming a lot, they need to be replaced.

Addy protocol: I'm no HVAC expert, but I work with someone who is HVAC certified, and I service 214 fan-coil units and 3 air-handlers at work, for a total of about 240 filters that I change every year, besides the ones at home.

Ken Fitzgerald
11-19-2017, 8:39 PM
You only have to remove the covers from vents in an older home, look into the pipe and realize why filters are important.

Every 5 years or so, I pay a company to vacuum our ducts out.

I use a 1" electrostatic filter that is washable and service it regularly.