Heating/Cooling guys come on in! (Hot upstairs, cold downstairs) :(

[Slimpsy1647545505]

Hey guys. Sorry if this seems like a silly question. But anyway. . . my wife and I purchased a home last year and it's a 2 story home on a slab foundation. Our previous home was a ranch style single story with basement and never had this problem. . . naturally. What we're experiencing and I'm reading mixed reviews from my research is our downstairs stays super cool right now with the thermostat set at 73. . . while the upstairs stays very muggy.

 

The house is about 8 years old. I have replaced the filter and everything seems to be running properly. The outside a/c unit is clean and free of debris. The downstairs vents push a good amount of air out, however the upstairs vents you can barely feel the cool air come out of them.

 

My concern is perhaps our unit outside is underpowered, or the duct work is shoddy. . . or perhaps 2 story homes on slabs are just destine to have this 2 story temperature conflict with thermostat downstairs and none upstairs in the warmer months? But man there is barely any air coming out upstairs.

 

I have tried closing vents downstairs to provide more circulation upstairs but it has not helped much if at all.

 

Do we have any economical options in this scenario outside of getting a window unit or something for upstairs? Is something wrong? This is your standard forced air setup, furnace unit is on 2nd floor.

 

Thanks for any and all advice. Sorry I really don't know much about heating/cooling

[caseyctsv]

I have not mastered it yet but you should have dampers in the ducts (little levers that close or open the duct) in the basement which direct airflow. Reduce the airflow to the ones feeding the downstairs vents and run the ones to the upstairs wide open. You should also buy some duct or aluminum tape and seal the seams in the ducts in the basement - there is a lot of air lost in shotty duct connections.

[Slimpsy1647545505]

I have not mastered it yet but you should have dampers in the ducts (little levers that close or open the duct) in the basement which direct airflow. Reduce the airflow to the ones feeding the downstairs vents and run the ones to the upstairs wide open. You should also buy some duct or aluminum tape and seal the seams in the ducts in the basement - there is a lot of air lost in shotty duct connections.

 

Right, but I am on a slab. . . no basement. . . just a concrete foundation. I assume perhaps a trip to the attic is in order.

[LJ]

Just my limited experience from owning rentals that are on slabs, is that yes there will be a temp difference due to the slab keeping things cooler downstairs. 2 story slab homes almost require a 2 zone system to keep them equal

[Slimpsy1647545505]

Just my limited experience from owning rentals that are on slabs, is that yes there will be a temp difference due to the slab keeping things cooler downstairs. 2 story slab homes almost require a 2 zone system to keep them equal

 

Ya, that's what I'm afraid of. Is it normal for the air pressure in upstairs vents on ceiling to be quite a bit lower than downstairs? I assume so due to the degrade of airflow throughout the ductwork and from downstairs. I really need to learn more about this shit

[Mallard]

I currently have a 1.5 story split level on a basement with the same issues. There's no way to get around hot air rising, and this is at the root of the issue. Do what others have suggested and play with the dampers so that you push more air to the upstairs. Check for leaks and crushed ducts, but that's about all you can do, aside from installing a zone system. We've had it 74 downstairs and 81 in my sons room. We've adjusted the dampers to push more cool air to his room and keep his door closed and that helped a bunch. Now theres only a 1-2 degree difference at most.

 

We finally found a ranch we liked and are moving in 2-3 weeks.

[Rocky31186]

My second floor is 10* hotter than the first floor. I asked my wife if we could move our master bedroom to the finished basement for summer.

[Duff1647545513]

Pretty common issue with one system, two story home. The dampers can be messed with, you can check for crushed/detached duct, but most likely it's just bad airflow that happens almost all homes with your set up. You can zone it, it's not cheap once the boards and dampers and installation all gets added up. Another option would be a mini split system, research them a little, they're gaining popularity. Or you can go more expensive and put an air handler in the attic with duct work and make your upstairs plenty cool

[XChris1632X]

As long as it is not a modulating furnace you can install a zone system with a couple dampers and thermostat up stairs.

[gillbot]

I got a Nest thermostat through work and it allows you to set a schedule to run the fan only to help even out temperature zones within the house. Before there was usually more than a 5 degree difference upstairs to downstairs but since adding the nest and turning on fan only more to run the fan 15 mins per hour, the temperatures are pretty even throughout the entire house all day.

 

EDIT: Another thing to check is to be sure all the ducts are free and clear. Some of my return vent had a bit of buildup in it and cleaning that out also helped.

[POS VETT]

Before trying anything expensive, close most of the vents downstair; leave one or two farthest away from the thermostat open. Open everything upstair.

[Doc1647545523]

Since you were talking about low cost, something you might want to consider if you have access to the ducts going upstairs is an in-line duct fan such as this: http://www.amazon.com/gp/product/B00CQBKF9M/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

 

They come in many different varieties--some have AC cords, some need wired-in, some can be easily controlled with a remote switch or a remote thermostat.

 

This may not be the total solution for you, but could be helpful in combination with closing downstairs vents/adjusting dampers/perhaps a small upstairs window unit.

 

Some of the other solutions are better, but they're more expensive.

[spankis]

You may also want to verify that you have adequate return air ductwork from the upstairs. If you're not returning enough warm humid air back to the unit it will just be trapped. Whether your unit has enough ass to move the air could be a potential issue as well, but it has to have a viable pathway in order get sufficient air changes upstairs to condition it.

[Tractor]

Keeping the fan switched "ON" will help to more evenly control your temp, but its not uncommon to have nearly a 10 deg variance between floors.

[cstmg8]

I install HVAC systems for side income. There's a chance your system is undersized for the home, but since it's what you've got you can make a few abnormal adjustments. Close All of your downstairs registers, you can partially open some up later if you have hot areas downstairs. Then, check for air returns upstairs, if there are a few, block off the downstairs returns, saran wrap works well.

This is assuming that the upstairs and downstairs are similar in square footage. You wouldn't have to do this on a correctly designed system, but it's easy and common.

Hope this helps,

Shaun

[cstmg8]

Another option that really helps is a good fan blowing up the stairs. I use my carpet fan/blower in our split level, makes a big difference moving air up from the cooler downstairs.

I think Lowes and home depot carry them. Carpet blower, snail fan, squirrel cage, lots of names.

[Slimpsy1647545505]

Thanks for the wealth of information! I'm currently trying with all vents downstairs closed and everything upstairs opened. We'll see how that goes. I have a fan blowing up the stairs, but it hasn't really made a difference. Perhaps a heavy duty one is in order. Ultimately it's only a real PITA at night when trying to sleep in a 80 degree bedroom, even with fans on. Oh well. I'll get it worked out. Thanks again all!

[SRTurbo04]

Thanks for the wealth of information! I'm currently trying with all vents downstairs closed and everything upstairs opened. We'll see how that goes. I have a fan blowing up the stairs, but it hasn't really made a difference. Perhaps a heavy duty one is in order. Ultimately it's only a real PITA at night when trying to sleep in a 80 degree bedroom, even with fans on. Oh well. I'll get it worked out. Thanks again all!

 

Let me know what you try and if it helps any. The wifes and is condo is the same way our "basement" is Half way under ground and stays the coolest, the next floor stays at what we set it to and the next floor is a good 6-10 degrees hotter and we have tried closing vents and making sure nothing is clogged and nothing helps. With a baby on the way I need to figure out how to fix that issue the easiest way possible.

[TTQ B4U]

Check the duckwork and insure that the open/close handles are in the open position for the floors upstairs. I wouldn't be surprised if they are closed for the upper floors and open for the lower levels.

 

http://inspectapedia.com/aircond/ducts/Duct_Controls651-DFs.jpg

 

 

I would strongly advise against blocking any of the cold air returns on the lower level. You'll strangle the natural closed system flow intended and put undue strain on the blower motor.

 

You can also look into leaving the blower motor on 24x7 for a day or so and see how that load balances the system. If it works you can look into getting a dual speed fan for the house. Our system is set up with a dual speed fan as an option. On really, really hot humid days, we can leave it run in low (barely audible) when the compressor for the AC is off. Kicks up to 100% when the AC comes on.

[TTQ B4U]

Thanks for the wealth of information! I'm currently trying with all vents downstairs closed and everything upstairs opened. We'll see how that goes. I have a fan blowing up the stairs, but it hasn't really made a difference. Perhaps a heavy duty one is in order. Ultimately it's only a real PITA at night when trying to sleep in a 80 degree bedroom, even with fans on. Oh well. I'll get it worked out. Thanks again all!

 

 

Look into temp controlled fans in the attic to suck hot air out.

 

We use one of these in our mater bedroom on occasion too. Really helps pull the cool air up from the lower level. Especially nice if you don't have easy access to add an inline duct fan like what Doc linked you to.

 

http://www.ntsupply.com/images/products/4X10Almond_4w.jpg

[XChris1632X]

I am not a fan of closing all downstairs registers, especially if your house is undersized in regards to duct work. I have seen too many coils frozen solid with closed registers being a big part of the problem. Before i ever check refrigerant levels on any system I look at air 1. Air filter (3 out of 10 service calls this is the issue) 2. Registers open and then I make my way outside to 3. Check air flow on outside unit.

 

Your system will run longer and a lot less efficient. Start by researching static pressures at discharge points to fine tune what you do have and turn your fan to "on". Many fan motors run easier staying on rather than on and off.

[cstmg8]

These are all very legitimate concerns on a normal system, and should be considered. It is very hard to diagnose without seeing it, but I'm thinking his drive/condenser is not rated for the correct tonnage.

Any changes will require close monitoring, and should be adjusted accordingly.

Good luck

[turbospec29]

The most cost effective thing might be to just use a small window unit in one of the upstairs rooms...

[Slimpsy1647545505]

So after many adjustments and tinkering yesterday I was able to get the primary rooms upstairs a comfortable temp range. There are 6 vents downstairs and 9 vents upstairs. I ended up closing all but 2 vents downstairs and closed off 1 room upstairs entirely (the office) and the vents in laundry room and walk-in closet and left primary bedroom vents open and all doors open (minus closets/office) and while it was still hotter than downstairs it was within 5-6 degrees.

 

I will run it like this for awhile and keep tabs on things. It seems to be working so far tho! My only concern would be extra stress on the overall unit and it does seem to be running a bit longer than before so I will keep an eye on electric bill and such. If for some reason it skyrockets I may just go with a window unit and shut off the primary in the evenings.

 

Thanks again all!

[XChris1632X]

Keep an eye on the coil and top of the furnace for water. That will be signs its freezing up. If it is running longer I wouldn't be surprised if it doesn't freeze ot when we get to 98-100 degrees for a couple days. Make sire you keep a clean filter in there. A dirty filter will only hurry the process of freezing it if it is in fact starving for flow now.