furnace filter thickness differences

[ncbill]

I confess I only change the (1", MERV 8) HVAC filters twice annually.

With our separate room HEPA filters the HVAC filters don't seem to attract much.

 

[COcheesehead]

What killed us on our filters in the previous house was a lot of new construction all around us. Lots of dust in the air. I would change the filter every 90 days and it would come out dark grey.

 

[CO-guy]

What killed us on our filters in the previous house was a lot of new construction all around us. Lots of dust in the air. I would change the filter every 90 days and it would come out dark grey.

Last summer we swapped out the regular HEPA14 filters in our purifiers for HEPA14 filters made to handle wildfire smoke with increased carbon filtration and a finer pre-filter for easier cleaning. I cleaned the filters every 90 days or so before replacing them at the end of the season and each time I took them out there had a dark grey layer of soot across the pre-filter mesh.

I already have more wildfire specific filters for this year to replace to regular medical-grade filters in there now.

 

[GoBirds]

For the first time in 20 years of being a homeowner (2 different properties) I recently noticed that the air flow was not normal and had to replace the 16x25x1 filter earlier than normal. It made a difference.

 

[Time2]

Don't restrict the airflow of the door to the furnace room by altering the louvers, especially if you have gas or oil heat. That airflow is separate from the airflow going through the furnace to heat the home,
Filters have gotten pricey but many here are referring to high filtration (merv) and /or filters with electrostatic treatment. We have 6 filters for two systems. A lot of places charge the same for a 12x12 filter as a 20x14 unit. I only buy mid-price filters

I don't think you understood the plan. I'm would increasing the hole in the door by 3 times and install a larger louver panel on the outside. On the inside I would add a filter holder system to hold the filters against the door. Then, as I said, I would need to seal the door frame because the door now has the filtering and any leaks in the door seal allow unfiltered air to the furnace. Or, maybe you weren't responding to me.

 

[jazz4cash]

I don't think you understood the plan. I'm would increasing the hole in the door by 3 times and install a larger louver panel on the outside. On the inside I would add a filter holder system to hold the filters against the door. Then, as I said, I would need to seal the door frame because the door now has the filtering and any leaks in the door seal allow unfiltered air to the furnace. Or, maybe you weren't responding to me.

I defiinitely do not understand the plan. What is the benefit of adding a filter to the louvers?

 

[Surewhitey]

Now that we are dog-less, we change ours every ~4 months. They're 5", merv 8's...

Amazon.com

 

[earlierme]

To be clear, the spec I was referring to was the 1” thickness.

Yep. 16 x 25 x 1 is what it says on the packaging.
I don't have calipers to measure it.
Using a ruler the thickness is about 15/16" at most.

 

[target2019]

Measured a Filtrete and old style. Both are 3/4 inch frame edge.

Where do y'all buy your filters these days?

 

[isisdave]

We switched from MERV13 to MERV8 filters for our HVAC system and purchased a whole house HEPA14 air purifier with PM2.5 monitoring

Will you recommend it to us? We have a Winix from Costco last year that we used in the 280sf room we spend most of our time in. We've just moved it to the bedroom instead of a tiny one and DW, who is the one that wants air purification, likes it in both places. Costco has a different, cylindrical Winix this year but I just ordered an Ecoself from Amazon ... great reviews, costs 60% less, supposedly good for 1500 sf so I hope it's not noisy, and it has 7 colors of lights, whoop de do!

 

[jazz4cash]

Measured a Filtrete and old style. Both are 3/4 inch frame edge.

Where do y'all buy your filters these days?

Amazon subscription

 

[CO-guy]

Will you recommend it to us? We have a Winix from Costco last year that we used in the 280sf room we spend most of our time in. We've just moved it to the bedroom instead of a tiny one and DW, who is the one that wants air purification, likes it in both places. Costco has a different, cylindrical Winix this year but I just ordered an Ecoself from Amazon ... great reviews, costs 60% less, supposedly good for 1500 sf so I hope it's not noisy, and it has 7 colors of lights, whoop de do!

We bought the Dayette brand products off Amazon and have been extremely pleased with both the purifier and the filter replacements.

AP401 True HEPA Air Purifier for Large Room up to 3000 sqft | DAYETTE.COM

【Efficient Purification with Large Coverage】Featuring with Turbo-air™ Technology, this CADR of 250CFM/400+m³/h air purifier equipped with a 4-Stage Filtration system including Pre-filter, TRUE HEPA Filter, Activated Carbon Filter, Net filter, can clean up to 3000ft² 1 time per hour, 600ft² 5...

www.dayette.com

 

[ERD50]

I don't think you understood the plan. I'm would increasing the hole in the door by 3 times and install a larger louver panel on the outside. On the inside I would add a filter holder system to hold the filters against the door. Then, as I said, I would need to seal the door frame because the door now has the filtering and any leaks in the door seal allow unfiltered air to the furnace. Or, maybe you weren't responding to me.

@Time2 I don't understand either, and I'm not sure you do, and there is a potentially fatal condition here.

I'm *assuming* this is a gas/oil fired furnace? And that it is not a 'sealed combustion" (high efficiency type that can draw air from outside with PVC exhaust). With a non-sealed combustion chamber furnace, the furnace draws combustion air through those louvers in the door. That combustion air goes into the furnace combustion chamber and out through the exhaust. The circulating 'room air' is kept separate from the 'combustion air' by the heat exchanger in the furnace. You don't want to be drawing room air through the furnace room, that's a recipe for disaster. For example, a gas leak could be circulated through the house.

So why do you want to filter the combustion air? That is not normally done, and any added resistance to the flow could cause a dangerous back-draft condition (CO in the room, fire backing up out of the furnace). This isn't making sense. Please be absolutely sure about what you are doing and why, and/or contact a professional to be certain this is a safe situation.

 

[Go Bolts]

I've had more than one experienced technician advise to buy the cheapest filters possible (we get ours at Home Depot) and the secret sauce is to change the filters Frequently.

This seems to be working well while saving some decent dollars on the filters. Those Filtrete and other high-end models are a lot costlier.

 

[COcheesehead]

I've had more than one experienced technician advise to buy the cheapest filters possible (we get ours at Home Depot) and the secret sauce is to change the filters Frequently.

This seems to be working well while saving some decent dollars on the filters. Those Filtrete and other high-end models are a lot costlier.

It depends. Mine is built to take the thicker filters and when I use the cheap, thin ones, the air suction bends them in half. The thicker ones stay flat.

 

[target2019]

I have two identical HVAC systems, so it is possible to compare different level filters. The environment is different between them (downstairs is large, upstairs is 1/3 the sq. feet.)

For a long time I used the standard MERV 1 filtrete 16x25x1 filters (both systems). Last year I tried MERV 5 pleated in both systems. The downstairs system soon started to whistle as the pleats dirtied up, and the motor pulled harder (ESM). So I had to change out to MERV 1. I noticed the MERV 5 was a bit bent.

The upstairs system services maybe 1/2 the area of downstairs, and had no noticeable problems.

So I'll continue with MERV 5 pleated upstairs in the summer, and have a carton of MERV 1 for downstairs.

I was told by the company that I should stick with MERV 1 with the ESM systems.

 

[pb4uski]

I've never seen a filter that thick. We have 2 different heat pumps, and they use very thin filters (1inch).

Ours is 20x25x4 Merv 11. I change it twice a year, just before we leave for the summer and just after we return in the fall. I buy them on Amazon, usually 2 to 4 at a time.

 

[kgtest]

Don't go overboard on the MERV rating. The 13s filter everything but kill the airflow. Terrible for your system.

I stopped running a filter. We don't run our system but only when needed, and open the windows as often as we can...so I'm not sure the filtering buys us much. I get the ducts cleaned instead every couple years now.

 

[jazz4cash]

@Time2 I don't understand either, and I'm not sure you do, and there is a potentially fatal condition here.

I'm *assuming* this is a gas/oil fired furnace? And that it is not a 'sealed combustion" (high efficiency type that can draw air from outside with PVC exhaust). With a non-sealed combustion chamber furnace, the furnace draws combustion air through those louvers in the door. That combustion air goes into the furnace combustion chamber and out through the exhaust. The circulating 'room air' is kept separate from the 'combustion air' by the heat exchanger in the furnace. You don't want to be drawing room air through the furnace room, that's a recipe for disaster. For example, a gas leak could be circulated through the house.

So why do you want to filter the combustion air? That is not normally done, and any added resistance to the flow could cause a dangerous back-draft condition (CO in the room, fire backing up out of the furnace). This isn't making sense. Please be absolutely sure about what you are doing and why, and/or contact a professional to be certain this is a safe situation.

Lost track of this thread. My thinking is same as yours but I was trying to avoid making assumptions without details.