Hot side of house - afternoon sun and ONE cold air return!


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Old 07-19-15, 08:58 AM
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Hot side of house - afternoon sun and ONE cold air return!

I need to know if I'm thinking this through correctly....I have a large space: kitchen, eating area and small family room on the afternoon sun side of a ranch home. There are 5 supplies for the cold air and one return that is tucked underneath a desk area. (which I use and currently has a CPU/Computer tower tucked inside it as well) This cold air return has (2) 8-inch ducts pulling air as best it can from the area.

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My concern is that because of its location (the desk obviously was an afterthought post design!) it's not pulling as much air as it can - hence the struggling temps in this room...

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Because the desk has a cabinet over the top of it, I'm thinking of maybe somehow opening up the channel in the wall between the studs and breaking out another grill above the cabinet to increase air flow - plus it would also pull the HOT summer air and I could damper it (closed) for winter use when air flow isn't such an issue as there is a fireplace in the small family room.

The thermostat for this floor of the house registers 4-6 degrees lower than in this room in summer and sometimes higher in the winter (but I run the fireplace too so it's hard to tell).

Currently there's a 2x4 on the upper side of the existing return....it appears that it's more than 1 16" stud span, but not quite 2 full spans of the studs - there's a strange "floor" constructed under the floor joists to enclose it....

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Any thoughts would be welcome! There's a gale force suction happening under this desk but I think it's insufficient due to its location not being on an "open" wall.....


Pam
 
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Old 07-19-15, 07:29 PM
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Only way to know is to have a heat load done to see exactly how much air you need.
 
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Old 07-19-15, 08:06 PM
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Oh my - how do you get a "heat load" done!? I have an HVAC person I use for some things - is it something he could do?

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Old 07-20-15, 10:53 AM
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Yes an HVAC company should be able to do this. Are you can down load a basic copy for about $50. Its called a manual J.
 
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Old 07-20-15, 04:43 PM
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Called my HVAC guy and he said I didn't need a Heat Load - just needed improved air handling and my idea of extending the choked up return was stellar! So it's all done!

The beginning mess........
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Cleaned up mess........
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Shot of both returns over and under.....
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So by tomorrow I'll know if it helped at all....

Pam
 
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Old 07-21-15, 01:02 AM
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Those look to be fairly restrictive grilles, I would suspect the free air area is no more than 50% of the grille area. I would also suspect that with that much duct area the louvers would "sing" badly.

Each of your 8 inch ducts have a cross-sectional area of about 50 square inches so a total of about 100 square inches. The chase formed between the wall studs is about 3-1/2 by 14-1/2 inches or about 49 square inches not counting any obstructions such as electrical boxes or wiring so the chase and upper grille would be serving one of the two ducts with the lower grille serving the other duct. The upper grille should have a free air area of at least 50 square inches, it should be printed or stamped on the back side.

I would seriously look at replacing those grilles with less restrictive models.
 
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Old 07-21-15, 01:46 PM
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Where would I find "less restrictive" grilles?

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Old 07-21-15, 03:51 PM
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I remember when I was young my parents got a new furnace. When they did, the grills on the returns would whistle like Furd mentioned. My dad took some snips and cut out every other fin on the grills. Problem solved.
 
 

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