How do I change my AC/furnace filter(s)?

3 years ago, I had a complete HVAC cut-in on my house. They installed a Lennox 12ACB air conditioner, a Lennox G40UH gas furnace, and an Aprilaire 2400 air cleaner. The systems all run great, but I've never changed any filters. Where are they is the question? I see that the Aprilaire one is easy to change. Is there also one on the A/C or furnace unit?
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ctd4x4 wrote:

Hi, No manual for each unit?
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Tony Hwang wrote:

I have manuals for the furnace, the AC, and the air cleaner. Only one that even mentions a filter is the Aprilaire Air Cleaner, which is installed in-line with the units. I'm guessing that's the only filter I need to change.
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ctd4x4 wrote:

I would expect a single filter.
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Joseph Meehan

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snipped-for-privacy@gmail.com says...

It sounds like the Aprilaire is intended as a whole-system filter, you may not have any other filters to change. That's how our house is set up, a Honeywell electronic air cleaner in-line with the furnace, no filter in the furnace, just the air cleaner unit.
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snipped-for-privacy@phred.org is Joshua Putnam
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