unhappy with HVAC in new house

nadams

Okay, so we moved into this new house 2 weeks ago or so. It's got central air with a thermostat downstairs only. All vents (downstairs and upstairs) come on at the same time, for the same length of time. Problem with that is that it stays much warmer upstairs than it does downstairs!

I'm sure that part of the problem is that my dad refuses to turn the thermostat below 76, which makes it 78-80 upstairs (what's the point of _that_?). We did install ceiling fans in all the bedrooms, but it still stays quite warm upstairs. Just the breeze makes in feel a little cooler.

Any of you experts know some secret tips on how to cool down the second floor _without_ turning the thermostat down? We have also closed off some unnecessary vents downstairs and make sure all vents upstairs are open, and returns not blocked.

Thanks,

nadams

phoneisbusy

No expert and no hvac but our furnace has a fan switch which turns on the blower. This helps circulate the cold air from our downstairs to the upper floor. It definitely helps. Does your thermostat have this option?

Good luck

Dave

nadams

Yes, there is a fan switch. It's either "auto" or "on". Right now we have it set to "auto", but we will try setting it to "on". Makes sense... doesn't it? Thanks,

nadams

jcaut

Sorry to say, I don't think you'll accomplish much without running it cooler downstairs. Heat rises. You really need separate units for upstairs and downstairs.

I've got the same situation, really, except that my house is 70 years old. The central heat/air unit was installed about 10 years ago, and frankly wasn't done very well. I replaced all the ductwork when I bought the house and that helped some (since air can actually move through it now), but the upstairs stays significantly warmer than downstairs. Of course, this old house is not insulated very well, AND we have 12 ft. cathedral ceilings upstairs, AND we live in Arkansas where it's not uncommon to have 100+ degree days with 70% relative humidity in the summer. It's not unusual for it to be 70 degrees downstairs and 85 upstairs.

So, if you find a solution, please let me know about it!

howie777

We had the same problem in our house. The solution, make sure all vents on all levels but the highest one are CLOSED. Then find all the spots on the duct work that go to those locations you closed the vent at and close down those ducts as close to the main one as you can (Their are levers on our ducts to due just this).

We had about 15 - 20 degrees difference between upstaires and the main floor and probably another 5-10 between the main floor and the basement. Now its nice and cool in the entire house! Since cold air falls, you only need to push it to the highest level, and closing as much duct as you can makes it easier on the fan to push it up.

Once I guessed on the ducts, I just checked all upstairs vents to make sure they were working and the difference was dramatic.

Hope this helps

Howie

nadams

That's an interesting concept as well. I do realise that cold air falls + hot rises, just wasn't sure if the falling action of the cold air would be enough to cool the 1st floor before the air got warmed up again. Also, the basement ceiling (1st floor... floor) is insulated, so it's always cold in the basement. I'm not worried about that, though.

Don't really want to permanently close off the downstairs vents, though... and I don't think that there are any levers on our ductwork to do this. I can check, though. I'm pretty sure I remember them just being straight ducts.

Early B.

Seems to be a general issue in 2-story houses. As jcaut mentioned, you should have two separate AC systems -- one for upstairs and one for downstairs. Our house has two systems and the upstairs is still several degrees hotter.

Do you have an attic? Do you have sufficient roof ventilation?

We have a "whole house" fan that sucks out hot air from the second floor and blows it out the roof. Works pretty well, except on real hot days. It's just loud as hell, though.

We spent a ton of money on duct work, but eventually resorted to mounting a $200 AC unit in the window of one of the rooms upstairs where we spend the most time. It turned out to be the best solution.

nadams

We do have a fully insulated attic... doesn't seem to have much in the way of ventilation. That could also be part of the problem.

And let me restate, this is a BRAND NEW house. You'd think that they would know better than to pipe a system like this in a new house. Why not make it work right the first time?!

Oh, and leaving the fan running all the time seems to be helping out, but I wonder how much electricity that's going to suck down. Probably not as much as turning the thermostat down to 70 just to get it comfortable upstairs .

Still, the second floor is cooler than it is outside, so that's a plus.

audiobliss

Originally posted by nadams
Still, the second floor is cooler than it is outside, so that's a plus.

Haha! Focus on the good, brotha!

nadams

Just talked to my dad and he said the attic has eve vents down both sides and a ridge vent all the way across the top. That's about as good as it's going to get w/o a powered fan up there...

bobman1235

Originally posted by Early B.

We have a "whole house" fan that sucks out hot air from the second floor and blows it out the roof. Works pretty well, except on real hot days. It's just loud as hell, though.

We had one of these in an old house we had, it was AWESOME. Didn't even need A/C most days, just open all the windows a crack and crank the house fan and you had a constant breeze throughout the house.

However, most codes no longer allow them, because they essentially cause your house to go up in an instant if there's ever a fire.

McLoki

As already suggested, close a few vents downstairs (about 1/2 way) and make sure all vents upstairs are open. (in the winter you will reverse this)

Set your thermostat fan from auto to on.

This cured a 10 degree differential in our house. it now stays within one degree from 1st floor to second. (you can close all the vents downstairs, but if all doors get closed upstairs (bedrooms) your AC will never shut off)

Make sure you have a decent air filter in your furnace and plan on changing it about every month and 1/2 rather than 3 months.

Michael

petrym

We had the same problem of the upstairs being too hot in summer, too cold in winter. When we replaced the AC/Furnace two years ago, the contractor constructed a separate supply branch for the upstairs (still used the existant up ducts). Then he added two controllable flaps inside the main floor supply branch (just outboard of the main supply plenum) so we could regulate the entire main floor supply.

We've found that the flaps need to be about 80% closed all year round for the main floor. That way most of the circulation goes upstairs and the temp is even throughout the house. Also we have the main fan on all the time per phoneisbusy's suggestion -- it works!

Dennis Gardner

Look at the positive side of this, your bedrooms will be the warmest rooms in the house during those PA. winters.

As a new house I would be calling out the HVAC contractor on a daily basis while you are still in your first year of the house. They may actually help you then.

You should make sure there is plenty of return air from the upstairs being pulled back into the sytem. This helps vacate the warmer air out of the top floor.

jdhdiggs

Our new house has adjustments you can make in the basement. Each HVAC conduit has its own sort of valve (I'm brainfarting all the correct terms). By adjusting these, you can control the flow of air through the house. Right now, our upstairs vents are wide open and downstairs is just cracked a bit. Fixed up an 8 degree difference.

Check it out.

caseymou

The cost is a little high, but try swapping out to a variable speed furnace blower and zoning system. The zoning system will automatically do what everyone else is saying - which is block supply air to the downstairs. The variable speed blower will maintain constant airflow - which means that if 1/2 of the vents are blocked, 2x the air moves through the open vents. Most blower motors tend to deliver less air when register vents are blocked and this can lead to "freezing up" the indoor coil during those hot days when your a/c runs continiously. The variable speed blowers deliver a set cfm regardless of the backpressure (up to a max. pressure).

Bottom line is that 2 story houses will always have problems balancing temps. 2 units are ideal - 1 upstairs, 1 downstairs. Properly designed/sized ductwork is critical.

Early B.

We had one of these in an old house we had, it was AWESOME. Didn't even need A/C most days, just open all the windows a crack and crank the house fan and you had a constant breeze throughout the house.

However, most codes no longer allow them, because they essentially cause your house to go up in an instant if there's ever a fire.

Hmmm. Didn't know that. I must have an old house.:eek: (it was built in 1980) Instead of disallowing them, seems to me a simple fix for this problem would be to make it mandatory to install a smoke sensor on the whole house fan that would automatically shut it down when it sensed smoke.

DAGLJAM6

Don't blame the A.C. man unless he did a sh**tty job, most of the A.C. contractors in my area try to get the builders to do the right thing from the start but most builders won't flip for a zone system or two systems in a two story house here either.
Builders just want "conditioned space" and don't seem concerned about true comfort levels based on latent heating/cooling loads on a given structure. Every home should have a true load calculation specific to that structures' location and orientation to daytime sun, these affect sizing of the equipment more significantly than most people realize.
In a nutshell two 1500 s/f homes , even the same floor plan , can vary on total load as much as a ton based on these calculations.

nadams

Well, after having the fan on all night, it seems to be comfortable upstairs now. Now, that's before it got all sunny and hot, so we'll see what it's like when I get home from work. also, all the rooms have blinds that are pretty much closed all day to try to keep a lot of the sun' s heat out. They really didn't seem to make much difference in the ambient temperature of the room, though. My room is the worst because it's on the corner that gets morning and afternoon sun. plus it's surrounded on two sides by the roof of the garage and porch. I'm sure _that_ doesn't help, either.

madmax

Move your bedroom to the basement...
madmax

Edit: Keeping the house at 70 degrees and not running fans, ceiling fans etc is cheaper than keeping the thermostat at 76 if that is what your dad is striving for. Took me awhile to figure it out but finally did. It also keeps your house drier in the summer and is much more pleasant. These days I keep mine at 70 and I'm quite happy when the electric bill comes. Your mileage may vary.

madmax

nadams

Well, we haven't even gotten our first electric bill yet, so we'll see what that's like when it comes . i know it's going to be higher than average, because our basement dehumidifier has been running pretty much constantly since before we moved in, trying to dry things out down there. We bought a new one, so hopefully it's a little better on teh bill. But still, with it running all the time (as long as we can keep the bucket empty) it's gotta be hard on it.

And yes, my dad is going for energy efficiency when he keeps it set up so high... we're going to have to do a month-by-month comparison once the months start . And, it doesn't help any that I'm used to having the thermostat set at 70 here in our little office! We have a rooftop unit all to ourselves that blows A/C out of 4 ceiling vents in a bedroom-sized room. It runs year-round,too. Servers generate a fair bit of heat, I guess

madmax

Originally posted by nadams
And yes, my dad is going for energy efficiency when he keeps it set up so high...

Tell him to chill out...
madmax

chuck13

Madmax is correct!! My house is cheaper to cool if I keep it at a constant 70 degrees instead of using the automatic thermostat that sets it higher when we are not home.

ND13

Originally posted by chuck13
Madmax is correct!! My house is cheaper to cool if I keep it at a constant 70 degrees instead of using the automatic thermostat that sets it higher when we are not home.

+1

jdhdiggs

What town are you at anyway?

nadams

Who, me? Bloomsburg. Just a bit Northwest of you

Edit- now that I look at it... mostly north....

jdhdiggs

just making sure you weren't the ones who moved in down the hill. My dog needs the bathroom.

nadams

Hahaha!

avelanchefan

Ok I live in AZ, and I had a bit of the same problem. I had certain rooms that were incredebly higher than others. We found a very nice solution called Solar Screen.

We Solar screened the windows in the rooms that were the higher tempurature rooms. The result? Now those roomes are the coolest rooms in the house.

It's amazing how much heat a window will create. But I am a believer now. Plus my A/C bills are much lower. Nearly 40%. If I do all my windows I think I will save around 60%.
Solar Screen

nadams

Where did you buy your solar screen from? That website is for distributers only. They don't sell direct . Would Lowes or Home Depot have these?

unc2701

There are two types of attic fans- the ones that suck air out of the house (mostly banned due to fire codes) and ones that circulate attic air. The second ones can make a big difference- mine went out and the upstairs jumped about 10 degrees. IT can hit about 120 in the attic, but if you can clear that out & get it down to the outside ambient temp, it makes a huge difference. I think it was about $90 at the hardware store.