Cold air down large staircases

[central nj]

Hi, I have 1500 sq ft upstairs serviced by what should be an oversized 3 ton ac. It can't quite keep up when the temp is high 90s inside is over 80.
There are two wide and open staircase going upstairs. Are they significantly contributing to the issue? How much of the cold air is "lost" to the other floor?

Thanks. Steve

[vstech]

the problem is threefold, one, you have cold air falling down the staircases, two, the warm air from down stairs is being pushed above it warming the air upstairs, and three, your attic is pummeling the ceiling with hot air, and radiant surface heating is occurring from the attic high temps as well.

energy auditing is your friend.

[central nj]

Ok but besides adding more insulation to the attic I wonder if there is anything else (1995 house well constructed)

And that also means that the 4.1 cooling load for the 1st floor is too high for my new ac to be installed in 2 days! Any way to estimate the cooling contribution? Any other fixes? Some sort of cross floor air circulator?

[George2]

Hi, I have 1500 sq ft upstairs serviced by what should be an oversized 3 ton ac. It can't quite keep up when the temp is high 90s inside is over 80.
There are two wide and open staircase going upstairs. Are they significantly contributing to the issue? How much of the cold air is "lost" to the other floor?

Thanks. Steve

The way I read your post is that you have a 3 ton A/C just for the (1,500 s.f.) 2nd floor? Do you have a A/C system cooling the lower level?

[danielworkerbee]

were are the second floor returns ?
luck dan

[hvacvegas]

Ok but besides adding more insulation to the attic I wonder if there is anything else (1995 house well constructed)

I just came from a "well constructed" 1999 home. Got up in the attic, There was a 10'x10' space that the insulators didn't blow celulose into, I guess because it was hard to get to. That, and half the attic only had 4" of celulose (which is worth about nothing).

That, and the massive attic (enough to play football in) only had 5, 6" roof vents, so no attic ventilation. It's been about 85-90* for the last 3 days, and about 130* in the attic.

Guess what? The second floor doesn't cool correctly.
Thats todays standard of "well constructed".

Energy audit.

[54regcab]

1st things I would check are the air filters and the condenser (outside part) to make they are clean. These are the 2 most common causes of poor cooling complaints.

[jtrammel]

Just because a house was recently built doesn't mean it was built well

[central nj]

Ok, thanks for the comments so far. 54regcag--had had the unit recently seviced, but it is 17 years old.

Jtrammel, good point. Will have someone look into it.

George2---yes. Two systems. Will be 4 tons downstairs. This great forum convinced me to literally beg the company to downsize from 5 to 4 tons for first floor. I had to sign a waiver. The load was 4.0-4.3.

Mr. Hvacvegas sir (thanks for help on other posts!!!)--got your point. I will have it looked at, good point.

Daniel Workbee—there are 5 low down near the floor, 16x10 return grills, one in each room, and one in the hall. 8 supplies in the ceiling (one in each room, bathrooms, 2 in the hall).

Maybe make the kids close the doors to all rooms? Would that kind of trap the cold air up stairs?

Regardless, how big of a cooling loss are the double open stairways? Will it mess up the load that was done for my downstairs unit?

Thanks
Steve

[hvacvegas]

Ok, thanks for the comments so far. 54regcag--had had the unit recently seviced, but it is 17 years old.

Jtrammel, good point. Will have someone look into it.

George2---yes. Two systems. Will be 4 tons downstairs. This great forum convinced me to literally beg the company to downsize from 5 to 4 tons for first floor. I had to sign a waiver. The load was 4.0-4.3.

Mr. Hvacvegas sir (thanks for help on other posts!!!)--got your point. I will have it looked at, good point.

Daniel Workbee—there are 5 low down near the floor, 16x10 return grills, one in each room, and one in the hall. 8 supplies in the ceiling (one in each room, bathrooms, 2 in the hall).

Maybe make the kids close the doors to all rooms? Would that kind of trap the cold air up stairs?

Regardless, how big of a cooling loss are the double open stairways? Will it mess up the load that was done for my downstairs unit?

Thanks
Steve

It's called "stack effect". Look up in wikipedia for more information. Learn alot about it for air sealing your home.

Your thinking the other way around though. If it's comfortable downstairs, but not upstairs, then keeping it open would help suck the heat downstairs. Heat always moves to cold, more so than "heat rises".

Unless I'm just tired and thinking backwards.

[energy_rater_La]

besides adding more insulation to the attic I wonder if there is anything else

lots of anything elses...adding insulation over air leaks is wasting money.
air sealing goes a long way to allowing insulation to perform.
air moving through insulation reduces insulation values.

living space walls that are shared with attic space have lots
of heat gain from hot attics. insulation alone doesn't do much
to solve these issues. if you insulate and then air seal the wall
with foam sheathing boards, then the living space is easier
to cool. and heat in winter time.

I'm not hearing good things about nj clean energy free audits.
it may be a starting point, but hiring an indpendent rater/auditor
would give you unbiased information that could save you much
more than minimal savings through utility sponsored audits.

best of luck.

[motoguy128]

Just because a house was recently built doesn't mean it was built well

Very sad and very true.

What hasn't been mentioned, is that much of the air movement down the stairs is partly due to reverse stack effect. Air leaks upstairs and cause warm humid air in the summer to leak in, and conditioned air leak out downstairs. The flow is reversed in winter.

The layout plays a major role, but I have a very wide open stairwell and there is cool air rolling down the stairs, but overall the upstairs is mostly isolated from the downstairs.

I would focus on attic insulation and air leaks (can lights, bath fans, ceiling fixtures) and attic venting.

[hvacrmedic]

It's premature to blame the capacity issue on infiltration. Have the unit checked out, then take it from there. There are several different issues that can result in low capacity.