Home HVAC filter- is 5" better than 1"

Hi - I'm getting quotes to replace my 25 year old furnace and A/C. House built in 1971, so 1970's grade of construction and insulation. Bungalow - about 1600 SF.

The standard unit comes with a 1" furnace filter and there's a option to get a 5" filter - the 5" will cost an additional $450.

Since we have lived here I've been replacing the 1" filter on our current unit every 2 months. Is going with a 5" a worthwhile upgrade? Is there a significant improvement in filtration or air movement between the 5" versus the 1"?

The extra cost isn't going to break the bank and im prepared to invest if it's a smarter move - looking or any real life experience on this.

Thanks, Paul

Is the 5" to be mounted where you will have easy access, or will the installer need to come back to change it?

My gut tells me it's a way for them to keep making money off the customer, but if you are especially sensitive to dust, there may be some benefit.

I've got both in our house, 5" in the upstairs unit, 1" in the downstairs. We have two cats and a dog, so for me I like the 5" because I have to change it less often. It is a pain to wrangle the big filter out, but I only change it every 9 months or so (or a year, depending). In a pinch you can always toss a 1" filter in a 5" holder, but you can't go the other way. I'd go with a thicker filter.

My guy says to buy the 1" and change monthly.  
 

My dad got a new furnace and I bought him a $10 filter that shut down the unit due to flow. Then we used the $.79 one and had no problems.  I thought that was odd.  

More filtering equals less flow (for the same size filter), makes sense to me.

This information is a few years old, but the home improvement guru guy that does the Saturday morning show on the local AM talker got in to the discussion about filters once when I was listening and his take on it was that you were better off having a cheap filter that you replaced every month or more instead of one of those really "good" filters.  His position was that the cheap-o filters would get most of the stuff in the air but that the better filters introduced too much restriction to the airflow and would have a similar effect to running a dirty filter for too long in terms of system efficiency.

I liked his advice because I'm a cheap sunuvabitch and it's a great answer to my wife when she asks if we shouldn't splurge and get one really expensive 3M filter instead of a half dozen of the Menards Specials.....

this isn't an electrostatic filter?  Seems like a lot of extra money for just an additional gap.

Datsun310Guy said:

My guy says to buy the 1" and change monthly.  
 

My dad got a new furnace and I bought him a $10 filter that shut down the unit due to flow. Then we used the $.79 one and had no problems.  I thought that was odd.  

Where did you find HVAC filters this cheap because I'm about to drop some serious coin!

The cheapest I've seen at like Amazon is buying a big pack of cheap ones and they were still like $8 each. 

We have to replace two at a time once per month because of the animals.

In reply to z31maniac :

they're dependent on size. The common sizes in the hardware store are like 80 cents each for the cheapest. 

0.72 each when you buy 4 or more (uh, ok). 

MERV number is used show a filter’s efficiency rating.  1” fiberglass throw away filters are typically MERV 3 or 4.   Most 1” pleated media filters at the home centers and hardware stores are MERV 7.   MERV 7 is roughly 35% efficiency and a good overall choice between filtration and air pressure drop.   I was able to source 1” MERV 11 rated filters from an online filter supplier; when bought in boxes of 6 the per filter cost was around $6.00 or similar to the standard pleated filters at HD.

The 5” media has more surface area and should allow a longer interval between changes and may be higher efficiency but you’d need to know the MERV rating to be sure.  Air pressure drop across the filter starts to increase significantly beyond a MERV 11 rating and can affect system performance, I wouldn’t recommend going beyond that.   Ask the contractor about availability of the 5” media for replacement, cost and the MERV rating before making a decision.   

I hate throwing things away, so I have a plastic and foam 'washable' filter instead of the cardboard and fiberglass ones I linked above. 

I'm not sure I've ever noticed a difference in system cost to run or air quality in the house or noise or anything. But I don't have allergies. I do know that not getting enough air flow to your furnace is bad. 

1" filter replace monthly when heat is on, we don't run AC so summer summer months it doesn't get run. 

Our unit has a 4" filter that is an oddball dimension, and the only place that has them is the HVAC contractor, who charges $45 each for them.  The filtering efficacy is definitely better, as is the airflow (more filter area), but I don't change the filter any more than I have to. I hate throwing away something that cost more than my first car!

Thanks guys for all the responses. This is a replaceable filter - not an electrostatic one.

I figure I'll look at the usual big box stores to see what the replacement cost is for filters.  and I'll confirm with the vendors regarding replacement. This filter will be at the base of the furnace - easily replaceable. But if I get the standard 1" filter and then later want to upgrade, it'll be a bigger job than just paying the difference up-front.

I keep up with this kind of maintenance quite well, so replacing more frequently would not be an issue. I tend to buy the cheaper brands - avoiding the Filtrete$$ ones.

In reply to Professor_Brap (Forum Supporter) :

In Alabama we dont hear crazy talk like that except from the dude that lives under the overpass. You "don't run AC"?

The house I rent has an AprilAire filter right before the air handler and UV after.  The air handler is in the attic, so every 4 or 5 months I go up and swap it out.  We have a Siberian Husky and two toy fox terriers that constantly go in/out of the dog door.

I love the filter setup.  The air is always clean.

In reply to Justjim75 :

Northern living, it's been hot lately but still not bad with having a old house and a nice breeze

We have the oversize box type filter, and run a 16 x 25 x 5 element in it.  It needs to be replaced once a year, costs about $30 at Menards, and does an excellent job as far as we can tell.  A whole lot better, I’ll say, than the 1” wide filter in out last house, even when I used a premium element in it, based on dust accumulation rate on the furniture.