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Q&A About Filters for Rheem Furnaces

Question: What are the filter sizes on the Rheem Classic 90 Plus?

Answer: The filter you need depends on both your furnace configuration (upflow, downflow or horizontal) and the width of your furnace's cabinet. See the chart below.

Furnace Filters for the Rheem Classic 90 Plus

Air Flow Configuration Cabinet Width Filters
Upflow 17-1/2" 2 15-3/4x25x1 filters
Downflow / Horizontal 17-1/2" 2 12x20x1 filters
Upflow 21" 1 15-3/4x25x1 filter
Downflow / Horizontal 21" 2 12x20x1 filters
Upflow 24-1/2" 1 15-3/4x25x1 filter 1 22-3/4x25x1 filter
Downflow / Horizontal 24-1/2" buy now on amazon 2 14x20x1 filters
Upflow 25" 1 19-1/4x25x1 filter

Question: What kind of filter do I need for the Rheem Criterion II Plus 2 LXE furnace?

Furnace Filters for the Rheem Criterion II Plus 2 LXE

Air Flow Configuration Cabinet Width Filters
All 17-1/2" 2 12x16x1 filters
All 21" 2 20x16x1 filters
All 24-1/2" buy now on amazon 2 24x16x1 filters

Question: Rheem model RGPH-12earjr filter size

Answer: For your Rheem RGPH filter you need to know your air flow configuration and the width of the front of the furnace cabinet. See the chart below with this information to find the correct filter size you need.

Furnace Filters for the Rheem RGPH

Air Flow Configuration Cabinet Width Filters
Upflow 14" 1 12-1/4x25x1 filter
(bottom air return)
1 15-3/4x25x1 filter
(side air return)
Downflow 14" buy now on amazon 1 14x20x1 filter
Upflow 17-1/2" 1 15-3/4x25x1 filter
(bottom air return)
1 15-3/4x25x1 filter
(side air return)
Downflow 17-1/2" 1 12x20x1 filter
Upflow 21" 1 15-3/4x25x1 filter
(side air return)
1 19-1/4x25x1 filter
(bottom air return)
Downflow 21" 2 12x20x1 filters
Upflow 24-1/2" 1 15-3/4x25x1 filter
(bottom air return)
1 22-3/4x25x1 filter
(bottom air return)
Downflow 24-1/2" buy now on amazon 2 14x20x1 filters
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