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HVAC filter / return advice

Patrick Ritchie
5 years ago

I have a 28 year old two story house (2700-2800 sq. feet heated) and I am replacing 2 original outside AC condenser units. We will probably be getting something in the Carrier Performance series or maybe an Amana. Two stage system upstairs, at least. 16 seer. I don't know yet. I have gas heat and I will be replacing the 2 furnaces and coils, as well. One is upstairs in attic and one underneath house in crawlspace / basement area. Currently, I have (2) 20X20X1 filters downstairs inside my house and (5) 14X14X1 filters upstairs inside my house. None at the units currently. So, I have 7 filters that I change every 3 months inside my house. I use merv 8 pleated filters that I buy at a local HVAC supply company. Yearly costs is not that bad, probably $154 for the two cases of 12. Probably yearly costs a lot less than that since the 20 X 20's last 18 months but I'm not getting into all the math in an effort to keep this brief. I asked some contractors about possibly putting in larger 4 inch filters at the furnaces instead of having 7 scattered throughout my house. As I understand it, the 7 scattered through my house woulds till be connected to the ductwork but it would be filtered at the units only and the filters in the 7 grills would be gone. Initially, I thought this was a grand idea and it was going to save me money on filters but after doing some math there doesn't appear to be any real cost savings. The 6 month larger filters at the units come with a yearly price tag of $140. Aside from cost savings factor, what are everyone's thoughts on benefits to the system, indoor air quality, etc. of having the filters at the units and keeping the 7 returns with no filters? I get the sense that not having the 7 filters at the grills inside the house may cause a lot of dust, etc. to get sucked up into the ductwork which may end up causing me to have to have that cleaned more often ? I thought about maybe having filters at the 7 grills and the units but that seems like overkill. Perhaps there are even more ways to do it. But, at the end of the day should I just simply leave it the way it is and just changing the 7 filters at the grills and not worry about filtering at the units and call it a day ? Please advise if you need more information. Thanks!

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