Do I need a return? How to help with Cooling on 2nd floor


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Old 05-28-19, 08:23 AM
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Do I need a return? How to help with Cooling on 2nd floor

morning everyone,

I've been reading like crazy on this topic, and keep getting conflicting info.

What would you guys do?

We have a 100 year old farmhouse. Central air was retrofitted who knows how long ago, but we have a HE A/C unit and air handler.

First floor cools exceptionally well, 2nd floor not so much.

There are returns in each room of the 1st floor, but not a single one on the 2nd floor, aside from the staircase.

My grandpa suggested using a wall cavity on the 2nd floor as a return, and I've identified a section that opens all the way to the basement. The only registers on the 2nd floor are in 2 of our 3 bedrooms (more on that below) and in the bathroom.

In the 3rd bedroom, we couldn't figure out why it was so cold in the winter and so hot in the summer. There's a register in the floor. I took the grate off, and found that there is no ducting. It's like they put the "register" in place to make it look like it was connected. Luckily, I can run a duct to it from below as it lines up with a duct in the kitchen.

How would you guys go about cooling the 2nd floor more efficiently? We've got fans running, and that helps, but as it gets hotter here in Cincinnati our bill is already climbing.

Really appreciate any feedback or ideas.

Side note, our siding is about to be replaced and the house Tyvek wrapped and air sealed at the same time. That should make a sizable dent right?
 
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Old 05-28-19, 08:36 AM
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The concept is simple - since hot air rises, you want to put returns in the highest points in the house to remove that air. Conversely, since the cooler air also falls, you want registers at that same height. Typically, vents are on outside walls and returns on inside walls to create airflow across the occupied portion of the room. Now, how you apply that idea to your home....
 
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Old 05-28-19, 08:53 AM
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Second floors are always difficult to cool since the furnace has to push the cold heavy air upward 2 stories.

So a simple test is to leave all the 2nd floor doors open and close off some of the supply to the first floor, does that help?

What speed is your blower on?

Yes the supply duct will help.

I dont think siding and wrap are going to make any significant improvement, they are not really a factor in insulating the house!
 
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Old 05-28-19, 09:13 AM
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So yeah, we usually cover the registers at night to keep the second floor cool. Works pretty well, at least for us.

Figured the wrap and airsealing would help, at least a little.

As far as blower speed, I'm not sure how I'd figure that out - we have a Nest T-stat, would I look there or physically open the air handler and check for a setting? The airflow is great, obviously a little lower on the 2nd floor.

For the return, could I simply connect the ducting to the existing return in the basement? Or do I need a totally separate "line" to the furnace?
 
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Old 05-28-19, 09:18 AM
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Right.

I've read though, people jumping in and saying that a return won't do anything because the system isn't balanced. Well, duh...so wouldn't adding the return balance it????
 
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Old 05-28-19, 10:52 AM
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I've read though, people jumping in and saying that a return won't do anything because the system isn't balanced.
Hmmmmm..... Is that in a different thread ?

You have the same problem every split level home has when A/C is added to a heating system. Adding a return to the second floor will absolutely make a difference. You are lucky if you are able to do that. In my house I don't have a clear shot and couldn't give up closet space.

Adding extra insulation in the attic to keep the heat from the second floor ceiling is also a big improvement.

Since you have a furnace more than likely A/C is on the high speed setting. You can open the blower service door and look for the control board. See which colored wire is on the COOL terminal. If you can't tell...... post the part number off the board.
 
 

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