Is opening large enough in furnace


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Old 07-30-19, 03:24 PM
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Is opening large enough in furnace

I was wondering if the opening area cut into the side of my furnace is sized properly. There is a 13" x 22" opening where the Aprilaire electronic air cleaner connects to the right side of the furnace. That works out to 286 sq. in.
The furnace is a two stage Amana 62K/92K btu furnace with a 3 ton Amana 2 stage A/C..Does this provide enough air for the heating and cooling?
 
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Old 08-01-19, 08:37 PM
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Welcome to the forums.

Is the hole in the side of the furnace the same size as the ductwork.
If it's smaller..... that could be a problem.
 
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Old 08-02-19, 07:58 AM
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Yea, what PJMax said. What is the size of the return air duct before the electronic air cleaner. My Trion Electronic Air Cleaner is 16" X 25" and rated at 1400 CFM. I doubt your furnace would be moving that many CFM.
 
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Old 08-02-19, 09:19 AM
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v,
Every ton of cooling equals 400 cfm's so your 3 ton unit is equal to 1200 cfm's. As PJ stated your return trunk should at least equal your supply trunk. A simple rule to remember is you will only get as much air out as you have coming in. You can go bigger with the return but should never go smaller.

Hope this helps a little.
 
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Old 08-05-19, 12:31 PM
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The opening on the side of the furnace is 13" X 22".
The return duct dimensions are 8" X 24" X 40'.
 
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Old 08-05-19, 01:13 PM
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So the hole in the furnace is slightly smaller than the duct size.
 
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Old 08-05-19, 01:50 PM
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The hole in the furnace is always a little smaller than the filter.

For a 16x25 filter, the hole may be like 15 x 24 or something.

A smaller than recommended hole can stress the blower motor if it's variable speed or lead to reduced airflow if furnace has a regular multi-speed blower.

To use the entire filter, the hole has to match the outlet of the filter, if it doesn't there needs to be a transition to the smaller size hole.

1400 CFM. I doubt your furnace would be moving that many CFM.
A 90k 95% 'er will move that kind of cfm.

The 80% version, closer to 1200.
 
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Old 08-05-19, 02:37 PM
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Aprilaire 5000

The outlet side ( facing the furnace) of the Aprilaire 5000 air cleaner is 14"-3/4" X 24"-7/8".
If that helps.
 
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Old 08-06-19, 07:36 PM
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the manufacturer should have the hole size in the install manual.

if it can be enlarged a bit, it's a good idea.

there's always a maximum size.
 
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Old 08-07-19, 04:56 AM
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13x22 is good for 1800 cfm at .08 friction loss
 
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Old 08-08-19, 09:30 AM
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when you have a filter, that doesn't apply.

a smaller than normal return opening reduces the effective filter area, increasing pressure drop across it.

unless there's a gap between furnace and filter and a transition to the return air opening.
 
 

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