Hot Upstairs - Solutions?

[Art Mulder]

I would love to hear advice from anyone who has dealt with the problem of a hot upstairs in their house.

We have a two story house. We have central air, and like most houses, the thermostat is on the main floor. The problem is that, even with the AC running, and the main floor a pleasant temperature... the upstairs is a few degrees warmer, and is not so pleasant for sleeping.

We are trying to minimize the electrical bill, naturally, so we set the thermostat to 25c (77f), which is a perfectly comfortable temperature. Unfortunately, the temperature upstairs is at least 2c warmer (4f), which makes quite a difference to comfort.

Is there any way to make the furnace suck more air from the upstairs? Cold air returns don't generally come equipped with dampers. Would blocking the main floor returns really make a difference?

We have a vaulted entry way - it is about 8x16, and contains the main stairway, and opens onto the upstairs hallway. (the upstairs hall is really a balcony wrapping around this entryway. I was thinking about suspending a ceiling fan in that space to circulate the air. That is a big deal, though, and I really don't want to attempt it unless it is guaranteed to make a difference.

The basement is positively chilly. What I really need is to get that air to circulate up to the 2nd floor!

So that is our situation. If anyone out there has dealt with this in a successful way, please share your advice!

[Steve Clardy]

We went with a window unit upstairs.

[Wes Bischel]

Art,
Not sure what might work in your situation, but with our little cape cod, we closed the doors to the bedrooms to keep the cool air from running down the stairs. (each room has supply and return)
We experimented with a few options and this worked best in our situation - I think in part because the only return for the downstairs in close to the bottom of the stairs (system was engineered in the '50's ) It may be that your two story entry hall is allowing all of the cool air pumped into the bedrooms to drop downstairs.

Good luck,
Wes

[Tom Hamilton]

Hi Art:

In hot and humid all the time Houston we put two units in most two story houses: upstairs and downstairs. Sounds to me like you my be a little underpowered, A/C wise.

The window unit would help in the master for sure.

Also, you might have your A/C guy do an analysis and make some recommendations based on the load and airflow. He may also be able to adjust the dampers in the attic supply lines and help some.

Good luck, Tom

[Art Mulder]

The window unit would help in the master for sure.

Also, you might have your A/C guy do an analysis and make some recommendations based on the load and airflow. He may also be able to adjust the dampers in the attic supply lines and help some.

Hey Tom,

- the Master BR is actually in better shape than the other two bedrooms, for a couple reasons. First, it is on the NE side of the house, so it does not get pounded by the afternoon Sun. The other two bedrooms are on the west side, and NW corner. Second, since we have an ensuite bathroom (with a door we leave open) it effectively has two air "supply lines" - the one from the MBR, and the one from the MBath.

- They build things different in Texas obviously. Around here, the ductwork for the second floor is in the walls and floor. I've never seen a house with ductwork in the attic. So there is no access to dampers for any of the second floor ducts (except possibly in the basement where the lines originate.)

Hey Wes,
Thanks for the suggestion, re: closing doors. With four active young kids in the house, doors do not get closed much. But that is something to try.

[Matt Meiser]

Our previous house, built in the early 1900's and with a 1950's duct system had the same problem. I found that closing the downstairs vents part way helped a lot. We also put a fan at the top of the stairs to pull air from downstairs on the hottest days which seemed to help.

[Tim Burke]

I've got the sme problem going on here. One thing we do is to run the furnace blower contonuously when A/C is on. This of course will send your energy bill in the wrong direction, but the blower draws only a fraction of the energy that the compressor does. This doesn't cure the problem, but it helps.

Like Matt said, we have reduced the flow to some downstairs vents to force more air upstairs. I have no doubt that there are air flow limitations to this method, so I have only reduced a couple vents.

I have a spot in my upstairs hallway that has no return air grill. I can easily cut one in there directly above the return air on the first floor. On the first floor there are 2 return grills in the same same stud cavities - one near the ceiling and one at the floor. If I cut one in upstairs, I may even remove one from the main floor.

Around here the new construction houses are getting 2 units if they are very large homes, or at least a main trunk line that runs to the attic and is distributed to vents in the ceiling.

Tim

[Perry Holbrook]

One possible solution is to install a "booster" fan in the duct work where you need more air flow. Do a google search for booster fan and you'll see some examples. I used one of these fan with a speed control in an exhaust booth over my welding table, fan plus control was less than $100.
Perry

[Tyler Howell]

As Matt said vent adjustment is key.
Speaking from industrial HVAC experience, It is an art form and science all it's own.
Air flow at each supply site should be measured. Equipment is pricy.
The old method of more for sites distant from the AC. Less for close works.
Don't forget good windows doors and insulation.
Ceiling fans get a work out year round here. Cheaper than the AC and very helpful in supplementing the comfort when you are conditioning the air.
Adding a thermostat controlled duct fan to the remote areas can help too.
Many ducts can adjust right at the room with the a small handle or knob.

[Ray Bersch]

Art, as Matt suggested, you may have to "re balance" the system for a/c. I have to do this in my townhouse - it is a symptom of a poorly designed HVAC system. So, I close off some vents on the first floor in the summer.

However, you may try some other tricks. First, be sure your attic is vented properly. I installed a thermostatically controlled power vent in my attic and it made a big difference. Attics can be twenty or thirty degrees warmer than the living area, especially if you have a dark colored roof.

Also look at your cold air returns. You may have a central return on each floor, or just one on the first floor - the best is for each room have a return and some systems even have a high/low set up in each room where the cold air returns can be open at top for summer and or at the bottom for winter. Anyway, warm air rises, cold air falls. If you have only one central cold air return on the first floor, it will take the cool air right back to the air handler while the warm air on the second floor has no place to go. If you have a central return on each floor, try restricting the flow of the first floor return - I put a furnace filter in mine just to slow down the flow of air through the 1st floor return and give the second floor return a better chance to circulate the hot second floor air. I tried closing off the first floor completely, but that was too much restriction for the size of my air handler.

If you do not have a second floor return, consider installing one - but first try opening the top half of your second floor windows just a little to allow the hot air to vent - experiment a little - just keep in mind the natural properties of air - warm rises, cold falls - and use it to your advantage.

Ray

[Michael Gabbay]

We had the same problem. When the main unit finally bit the dust we installed a dual zone system. The overall cost was in the new duct work which is in the attic along with the second air handler unit. I think we spent an additional $3,000. It has made a world of difference in heating cooling the house.

Mike

[Art Mulder]

First, be sure your attic is vented properly. I installed a thermostatically controlled power vent in my attic and it made a big difference. Attics can be twenty or thirty degrees warmer than the living area, especially if you have a dark colored roof.

Also look at your cold air returns. You may have a central return on each floor, or just one on the first floor - the best is for each room have a return ... If you have a central return on each floor, try restricting the flow of the first floor return - I put a furnace filter in mine just to slow down the flow of air through the 1st floor return and give the second floor return a better chance to circulate the hot second floor air.

Ray, good suggestions.
We actually have a return in each bedroom. In addition, there are two larger returns on the main floor (fam Rm + Dining). I like that idea of putting a furnace filter on the main floor returns to restrict flow.

I hadn't thought about the attic power vent, but now that you mention it, I recal other folks writing about how those benefit their houses. I'm pretty sure that our house has the "code" amount of attic venting, and I know that the soffit vents are clear. But we do have a LOT of south-facing roof (see attached picture - old/poor quality, but I had it online) so we may need an extra boost there.

Thanks also to Tyler, Tim and others. I'll have a closer look at the vents and see what I can close off or reduce for the summer (ie: the basement)

[Jerry Olexa]

THE HOUSE WE LIVE IN NOW HAS 2 a/c's. When we had it serviced a few years ago, they stressed: heat rises, cold falls. So we now often run the furnace in Winter downstairs only and The A/c in summer upstairs only. The cool air finds its way downstairs and it works!! Further, an attic fan would help as well as a portable or window A/C unit upstairs. Lastly, I would block all downstairs vents and open up fully the upstairs. Just my layman's experience. HTH

[Cliff Rohrabacher]

Vent the attic. It cam make a 20 degree difference. The ceilings are likely a source of infared radiation. Most roofs are massive heat sinks and the attics get brutally hot. It's bad for the shingles too.

[Jim Becker]

I have a fan at the bottom of the back stairs and another on the landing outside of the MBR to keep the colder air moving up and through the second floor. (our "warm" issue is exacerbated by no insulation currently in the ceiling of the 250 year old portion of the house and not enough in the 1950's section...it will be dealt with as part of our home addition project when we re-roof) The small fans don't use much energy and really do set up a nice flow that just doesn't happen with the air duct distribution.

Oh, I agree with Cliff...but ours is already "vented" as it's cedar shake over lath and you can see the sky on dry days...