Upper level cooling advice

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Old 06-12-17, 05:04 PM
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Upper level cooling advice

Hey everyone! So this is the first summer in our home (first time home buyer as well) and I'm a bit upset with the cooling in the upper level of the home. It's a split level home - lower level, main level (kitchen and living room) and upper level (bedrooms). Air conditioner and furnace are fairly new maybe a few years old and we have a Nest smart thermostat on the main level.

Now that it's hot out we notice how the cool air isn't distributed throughout the home very well - it's ice cold on the lower level and pretty warm on the upper level, main level is on the colder side as well. This isn't an issue during the day but at night when we go to sleep it's annoying because it's uncomfortable upstairs to sleep. Here's the layout of the home:

Thermostat at 72 degrees - 66 to 68ish at night time (still pretty warm on upper level and lower level you need a hoodie). Fan is set to always on.

Lower level has 2 supply registers on the ceiling and 1 return register on the wall about 2ft from the floor.

Main level has 3 floor supply registers and 1 return register on the wall right above the floor.

Upper level rooms have 1 floor supply register each and 2 wall return registers each (1 near the ceiling and 1 near the floor).

Any advice, tips, or recommendations on how to get the upper level cooler so it's comfortable without having to turn the thermostat down to the 60's and having the North Pole on the main level? As of right now here are my ideas:

1) Remove all supply and return registers and make sure all ducting is properly sealed and not leaking air anywhere.

2) On the upper level - close the lower return registers so it only removes air using the top return registers.

3) Completey or partially close the supply registers on the lower level.

4) Partially close the supply registers on the main level or completely close 2 and leave only 1 open.

5) Relocate the thermostat to the hallway which is on the upper level (only concern I have with this is that there are no supply or return registers in the hallway - worried that it might cause the unit to run for too long due to not having adequate airflow to determine temperature; thoughts?)

I know about calling an HVAC guy and having him do a test and/or load balance the registers but I'd like to leave that as a last resort.

Also the filter was just replaced. I also do not have access to ducting for the upper levels as it is all under the floor boards and I don't have any intention to rip all that apart.

Thanks in advance!
 
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Old 06-12-17, 10:14 PM
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Welcome to a typical split level home with one air handler/furnace. Same setup I have.

Although it appears your duct work was setup for heating and cooling with the upper and lower returns on the upper level.

On the upper level - close the lower return registers so it only removes air using the top return registers. Yes.... that's why they are there. Upper return for summer, lower for winter.

Type and location of thermostat has no effect on temperature balance thru the house.

Remove all supply and return registers and make sure all ducting is properly sealed and not leaking air anywhere. How would you do that.... open all the walls ?

Completely or partially close the supply registers on the lower level. YES. The lower level should require very little cool air. Cold air travels downwards from the upper levels. My split level has no door to the lower level and is like an iceberg with all registers closed.
 
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Old 06-13-17, 06:11 AM
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2 floors 2 units. This is the only way to make this correct.
 
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Old 06-13-17, 10:14 AM
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Originally Posted by airman.1994
2 floors 2 units. This is the only way to make this correct.
Can you elaborate? This sounds extreme for a residence.
 
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Old 06-13-17, 02:35 PM
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They are done this way all the time. The reason its so hard to get the temperature within a degree or two is because you are talking about two completely different zones. Even with the correct size duct the air is going to take the bath of least resistance. So naturally the air will settle on the lower floor. Two systems is always recommended for comfort and redundancy when you have a two story home.
 
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Old 06-13-17, 03:06 PM
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Two systems is better but as long as the system is running, I get decent results with Pete's method of closing lower level vents in the summer and upper level vents in the winter.
 
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Old 06-13-17, 03:15 PM
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I get decent results with Pete's method of closing lower level vents in the summer and upper level vents in the winter.
That's excellent that you have the dual setup.

My house was built in '59 and I only have lower returns and it's miserable.
Someday I'll extend them up.
 
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Old 06-13-17, 03:19 PM
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I never built a split level but helped on a few and the paths between floor levels was a maze. I suspect the ducts were not well sealed and the returns used stud cavities where they could, very common. But that isn't going to change.

My perspective is preventing heat gain as opposed to addressing the supply of cool air. After all adjustments that have been suggested are done there is still the possibility of more insulation and most importantly air sealing. If you have access to the attic that is where you would start.

Let us know if the adjustments help and if you wish to discuss air sealing. As a note, during the hotter months natural air leakage occurs with the cold air pushing out the lower levels of the house allowing the very warm air in the attic to replace it, starting with the upper floors. That air leakage is not trivial, sometimes as much as all of the air inside your home being replaced every 3 or 4 hours. When the ac is off it doesn't take long for the house to warm to outside temps.

Bud
 
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Old 06-13-17, 07:27 PM
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Okay so I've figured out a few things after looking over the ducting and all that fun stuff.

First, I used duct tape to seal the opening where the air filter is inserted, it didn't have a cover or anything - just slides in. Not sure if that should normal or not.

Second, I found a supply damper closed off that goes to the upper level bathroom. Opened that up so I should be getting more cool air up there.

Third, I slightly adjusted the dampers that feed the basement so they're partially closed. These are on the same main duct that feeds all the upstairs rooms.

Fourth, the return registers for the main bedroom weren't doing a very good job - wouldn't even hold a piece of paper against them. So I looked at the main return ducting that's for the upstairs and it has a register at the very end of it - right where the smaller ducting goes to the main bedroom. So I taped that register off and now the registers in the main bedroom are working a lot better - can actually hold a piece of paper against it.

Fifth, the attic has two fans that are connected to temperature adjustable thermostats. Well I realized those were shut off because they are fed power through a switch that's in the closet in one of the bedrooms and it's always been off (had no idea what it was for). Now for these attic fans what should I set the temperature dial too? At the moment they're set to about 95 degrees but they aren't running... so I turned the dial down to see if they work and they don't turn on until the dial is turned to the 60's which doesn't really make any sense as it's over 95 degrees outside and I really doubt the attic is only in the 60's. I don't have a thermometer handy so I can't accurately check.
 
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