advertisement
Deals | News | Forums

The Forum is sponsored by 
 

AAPL stock: $524.94 ( +5.93 )

*Cached every 60 seconds. For live updating, Click Here

You are currently viewing the Tips and Deals forum
cold downstairs, hot upstairs, what to do?
Posted by: davemchine
Date: July 06, 2006 06:49PM
I just bought a two story house and it is cold downstairs and hot upstairs. I've closed the downstairs vents 90% but now they whistle something fierce and I'm still not getting the temp evened out. Should I stuff insulation behind the vents and completely block them?

Dave
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: bazookaman
Date: July 06, 2006 06:54PM
I have the exact same problem in the top 2 floors of my townhome. What i end up doing is in the winter, I climb into the attic and completely close the dampers for the upstairs. This makes it nice and warm on the first floor and nice and cool on the top floor for some fine sleeping. In the summer, i do the opposite b/c I NEED it to be cool upstairs when I sleep. Its a PITA, but i only do it twice a year. And since the vents are shut off at the source, no whistling.

I think there are some mechanical means of regulating the "zones" but I never looked into it very hard.




__________________________________
Never underestimate the predictability of stupidity
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: msglee
Date: July 06, 2006 06:54PM
If it's a Cape, get an air cond. for the window. If it's a Colonial, check the returns.



Eastern Baltimore County
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: earache
Date: July 06, 2006 07:11PM
I just moved into a 2 story house. We had a 2 zone HVAC system put in and couldn't be happier. The week we had the system installed we were seeing 100deg. temps. I honestly don't know how the previous owners lived there without AC. The zone system works really good. 2 thermostats, one downstairs and one upstairs, each controlling how to handle the air whether hot or cold. Pretty slick. Cost an arm and a leg, but so worth it.

If a 2 zone HVAC is not possible, try a whole house fan.



earache



Edited 1 time(s). Last edit at 07/06/2006 07:12PM by earache.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: shadow
Date: July 06, 2006 07:25PM
Quote
earache
If a 2 zone HVAC is not possible, try a whole house fan.

If you have AC, you already have a whole house fan ... move the "FAN" switch on your thermostat from "AUTO" to "ON".

You'd be amazed how little it costs to run the blower (not the compressor) 24/7 and this _should_ be enough to overcome the stratification that is happening in your house.

- Shadow
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: M A V I C
Date: July 06, 2006 07:38PM
Doors, get some. Seriously. My house now is three stories and I have the issue you describe. That said, I regulate it based on which doors are open. Gets hot? Close upstairs doors and open downstairs doors.

If I put some doors in the stairwell, that would help even more.

Most US home, IME, don't use doors to aid in the heating and cooling of a home. In Europe, they are used very much so to do that.




Help MacInTouch: Buy from Amazon? use this link [amazon.com]
Mac News & Info: [macintouch.com] [macnn.com] [tuaw.com]
Mac Benchmarks: [barefeats.com]
Used Mac Stuff [FS/T]: [macswap.org] LowEndMac Swap List
Mac Software Updates: [macupdate.com]
Fonts: [dafont.com] [fontspace.com]
Online Computer Store With Mac Support: [macsales.com]
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: wowzer
Date: July 06, 2006 07:45PM
Put putting filters in the air vents that are whistling.

Sometimes a little cardboard will do...other times, try a foam insulator...like the ones that come with the packaging for hard drives.

GL.



All I ever really needed to know, I learned from watching Star Trek.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: davester
Date: July 06, 2006 07:50PM
I think you're going about things bass ackwards. The problem is probably that you are getting too much heat gain upstairs from poor insulation/attic venting, and the AC is therefore freezing out the downstairs as it works unsuccessfully to counter the heat gain (all while draining your pocketbook for utility costs while pumping mass quantities of CO2 into the atmosphere). In many cases, the FIRST (and the cheapest when you consider electricity costs) thing to work on is reducing the heat gain. Check things in this order:

1) Is the attic vented? You need both high and low vents in about a 50/50 ratio to allow convection to move the hot air out of the attic; the vents should be at least 1 square foot per 150 square feet of attic floor area.

2) Do you have R-19 or better insulation above the upstairs ceiling.

If neither of the above minimum requirements are met, then it's unlikely that any amount of fiddling or upgrading the AC will help you.

3) Do you have either low-e windows or low-e film on the windows on the southern sides of the house. Film is relatively cheap if you don't want to spring for new windows. This will significantly decrease solar gain. Light colored blinds or curtains will also help.

4) Only after you have met the above requirements should you start looking at whole house fans. There are a lot of pitfalls with these and you need at least double the attic vent space as you do whole house fan vent area.




"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: blooz
Date: July 06, 2006 07:56PM
I'm hot downstairs, but she's cold upstairs.



Be here now. Be someplace else later. Is that so complicated?
Zen is not easy. It takes effort to attain nothingness. And then what do you have? Bupkes.

Western Massachusetts
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: Speedy
Date: July 06, 2006 08:14PM
Yup, leaving the fan run all the time works for us. Winter and summer. And be sure to change the furnace filter as needed.

Quote
shadow
Quote
earache
If a 2 zone HVAC is not possible, try a whole house fan.

If you have AC, you already have a whole house fan ... move the "FAN" switch on your thermostat from "AUTO" to "ON".

You'd be amazed how little it costs to run the blower (not the compressor) 24/7 and this _should_ be enough to overcome the stratification that is happening in your house.

- Shadow



Saint Cloud, Minnesota, where the weather is wonderful even when it isn't.



Edited 1 time(s). Last edit at 07/06/2006 08:16PM by Speedy.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: Pam
Date: July 06, 2006 08:25PM
I have the same problem, and I know I need more insulation in the attic. That said, be very careful about shutting the vents off so much downstairs. That strains the AC system and is counterproductive. You should only have 25-percent of the downstairs vents closed no more than 60-percent.

Heat rises, a dual AC/heat system is the ultimate way to go. In leiu of that, make sure your window coverings help you retain heat and cold, and use them! Door closings is not usually the answer. In fact that usually results in more uneven heating and cooling.

When you can do it, get more attic insulation, install ceiling fans, and plant trees.

The summer may suck, but upstairs will be your friend in the winter ;)
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: davester
Date: July 06, 2006 08:28PM
Here's a useful link: [www.airvent.com]

Also, an AC fan running all the time is NOT a whole house fan (WHF). A whole house fan sucks air out of the house and blows it into the attic, which thereby cools the house by exhausting through the attic vents (that's why you must have lots of attic vents with a WHF. Running the AC fan will not move any heat out of the house or cool the attic, which are the key requirements. All it will do is mix the air in the house. This may make things more comfortable but it still will cost an arm and a leg for cooling because you are not addressing the main problem.




"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: davester
Date: July 06, 2006 08:31PM
Quote
Pam

When you can do it, get more attic insulation, install ceiling fans, and plant trees.

This stuff is useful, but the attic insulation advice is bad advice if you don't first vent the attic. The insulation will actually hold in the heat and make it difficult to cool the house in the evening. The first thing is to control the attic temperatures with venting.

If you are in a very hot climate, another cheap way to keep the attic cool is to put in radiant barrier material hanging from the rafters. Real easy to do, and stops the attic roof from radiating heat towards the attic floor.




"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: sscutchen
Date: July 06, 2006 08:39PM
Quote
msglee
If it's a Cape, get an air cond. for the window. If it's a Colonial, check the returns.

I have a 2 story house, and I honestly have no clue what this means.





Don't ask who the bell's for, dude. It's you.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: Harbourmaster
Date: July 06, 2006 08:40PM
If you want to be cold, go down smiling bouncing smiley

If you want to be warm, go up hot smiley



Aloha, Ken


“I have developed significant attachments to several members even though I wouldn't recognize them if I sat next to one on a park bench. I'm often tempted when in an airport to walk around, hollering "The Løpe", to see if anyone other than the Homeland Security people will acknowledge me. ” - The Løpe
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: Phy
Date: July 06, 2006 08:57PM
Quote
blooz
I'm hot downstairs, but she's cold upstairs.

Blooz, do as MAVIC says and keep your door shut!!
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: iaJim
Date: July 06, 2006 09:23PM
Two zones is the real answer. The insulation is a good idea too, and attic venting if you don't already have it.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: ajakeski
Date: July 06, 2006 09:34PM
Cold air being heavier, you should look into a faster furnace fan. This can be done with a change of the fan's pulleys. Most new furnaces have two speed fans. Slower for heated air and faster for cold air.




I'm not a bad guy! I work hard, and I love my kids. So why should I spend half my Sunday hearing about how I'm going to Hell? -Homer.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Date: July 06, 2006 09:57PM
Davemchine, where is the return for your heating/AC unit? If it's on the lower floor (as are most), it isn't sucking in the hot air that needs to be cooled the most. For cooling purposes, the return should be in the upstairs hall ceiling so it can get the hottest air in the house. Of course for heating just the opposite is true and the return should be as low in the structure as possible to pick up the coldest air.
What I would do is route a second return to the upstairs for use in the summer and have a "winter/summer" valve to switch between the two seasonally, but this method might not work for everyone or in every home.
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: shadow
Date: July 06, 2006 10:20PM
Quote
davester
Also, an AC fan running all the time is NOT a whole house fan (WHF). A whole house fan sucks air out of the house and blows it into the attic, which thereby cools the house by exhausting through the attic vents (that's why you must have lots of attic vents with a WHF.

And where, pray-tell, does the replacement for the air that you just sucked out of the house come from?

That's right, outside.

Do you know what the largest factor affecting a Manual J calc is? Air exchange. A whole house fan does the worst thing possible when you are trying to condition air - suck unconditioned air in from OUTSIDE. You are saying it takes less energy to cool hotter, OUTSIDE air than it does to cool drier, inside air.

It's bad enough to have air exchange due to poor insulation (< R-30 in the attic, for example). It's downright moronic to do it purposefully without the proper equipment (a high efficiency recovery ventilator). Whole house fans have their place, but they simply should NOT be part of any well designed HVAC system.

Quote
davester
Running the AC fan will not move any heat out of the house or cool the attic, which are the key requirements. All it will do is mix the air in the house. This may make things more comfortable but it still will cost an arm and a leg for cooling because you are not addressing the main problem.

Mixing the air in the house is probably EXACTLY what you want to do in this situation. A lot of the stratification occurs simply because the heat load is greater on the second floor and the thermostat is on the first floor. When the demand for cooling is satisfied on the first floor, the unit turns off, leaving the second floor too warm. By leaving the blower on full time, you mix the cooler air from the first floor with the warmer air of the second floor giving the building a much more uniform temperature profile; a side effect is that the thermostat is more accurate.

Will this use more energy? Of course, but this is simply because you are doing more cooling. In a stratified house, for example, you may be cooling 90 deg air down to 85 on the second floor and 75 on the first floor - a total of 20 degrees of cooling. In a uniformly conditioned house, both floors will be cooled down to 75 for a total of 30 degrees of cooling.

As far as costs above cooling, running the blower 24/7 costs around $7 / mo more than if you let it run only when the compressor is on.

Obviously, if you can add insulation to the attic, it will do nothing but help.

- Shadow
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: shadow
Date: July 06, 2006 10:32PM
Quote
Thrift Store Scott
Davemchine, where is the return for your heating/AC unit? If it's on the lower floor (as are most), it isn't sucking in the hot air that needs to be cooled the most. For cooling purposes, the return should be in the upstairs hall ceiling so it can get the hottest air in the house. Of course for heating just the opposite is true and the return should be as low in the structure as possible to pick up the coldest air.
What I would do is route a second return to the upstairs for use in the summer and have a "winter/summer" valve to switch between the two seasonally, but this method might not work for everyone or in every home.

A properly designed system should have returns throughout the building. In fact, each room with a supply should have a return or be connected via an unobstructed path to an area with a return.

If you don't, you'll build up static pressure within the system, drastically reducing the life of your blower. Additionally, you'll end up with rooms that are "dead zones" that don't get properly conditioned.

HVAC calcs are complicated, but fairly straight-forward. With a proper design (Manual J), you will know the load in each room, how many CFMs you need, and how big the supplies and returns should be.

- Shadow
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: decocritter
Date: July 06, 2006 10:58PM
I have the same problem in a two story with a basement (where the hvac is and it is heated and cooled). I have returns in every room. I also have a flat roof and not much attic.

What do you mean close doors. I thought that, and closing vents was counter productive and could damage the unit.

What kind of window film are you suggesting?

Can I close vents and door in an upstairs room that faces south and heats up like an oven?
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: davester
Date: July 06, 2006 10:59PM
I don't know what your angle is shadow. You seem to be taking an argumentative tone with what I posted, but you are agreeing with me.

1. I didn't say that a whole house fan was a good thing, I just explained that an AC fan running all the time is NOT a whole house fan as you originally stated. Whose house fans must be used with the downstairs windows open and my understanding of them is that their primary purpose is to rapidly cool down the upstairs floors of a house during the evening hours when outside makeup air is cooler.

2. I pointed out that running the AC fan all the time would increase comfort but not give any $ savings, whereas addressing the probable primary problem first (overheated attic and solar gain from windows) first was the smartest line of attack. Why are you arguing...you essentially backed up my statements.

It is not obvious that adding insulation will always help. In hot climates the insulation can have too much thermal inertia and keep the house from cooling down at night if you don't properly vent the attic and/or use a radiant barrier in the attic. The reason for this is that most heat gain in the summer is due to radiant energy, and insulation has no effect on radiance...it only reduces heat transfer via convection and conduction. This is probably one of the least understood (but most important) aspects of insulation.




"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: davester
Date: July 06, 2006 11:04PM
Quote
decocritter
I
What kind of window film are you suggesting?

Any kind of window film that is labelled "low-e" will reduce the amount of radiant energy that comes through the window and heats up the inside of the room. There are different types....some is invisible when put on, some has a mirror-like appearance. There are services that will come out and put the film in for you. I bought some film with an installation kit and did it myself. There are a bunch of companies that make it. Here's one: [solutions.3m.com]




"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: shadow
Date: July 06, 2006 11:05PM
davester:

Sorry about that - sometime it is hard to "turn it off" after a long day with clueless clients and little sleep (not that I'm complaining about this last one because it is due to my 7 day old).

- Shadow
Options:  Reply • Quote
Re: cold downstairs, hot upstairs, what to do?
Posted by: mikebw
Date: July 07, 2006 02:39AM
Here is my take on the whole situation- mostly rehash.

The thermostat is located on the middle floor, and since heat rises the top floor will never reach the correct temperature unless you take further measures.
The biggest problem I encountered at the previous two houses I lived in was that there was only 1 air return for the whole second floor, and it was actually located on the 1st floor in the stairwell up to the 2nd floor. There is no way the heat from the attic and/or ceiling of the 2nd floor will get sucked down into that vent by itself.
After making considerations for proper insulation, I figure you have two options for evacuating this unwanted heat.
1- Vent it outside, 2- Bring in more cold air, and 3- Force it into that return to be cooled by the AC.
Most effective for me has been a combination of #1 and 2. At night when it is cooler outside than in, I simply open up two windows, set a box fan on the ledge of each and have one blow in, one blow out. This provides cross-ventilation, and will move the most air.
Of course this is not a good idea during the day if it is really hot outside, since you are likely just going to bring in more heat. When the sun is up I recommend just closing up all the windows and running the AC with the fan on all day long.
Option #3 would help, but so would having an attic exhaust fan. As was mentioned, you don't really want to add hot air to the AC to make it work harder if you have the option of evacuating it to the outside.
Options:  Reply • Quote
Sorry, only registered users may post in this forum.

Click here to login