Any A/C cooling experts around here?

[rlcramer]

I had central AC installed in my house a few years back as part of a major expansion / renovation. I am ETERNALLY hot, and the central AC was literally the one thing that I was most looking forward too when the renovation was completed - even more than having my own studio...no joke.

Anyway - I have a 2 zone set up, blower / air handler / ducts for the upstairs, and a completely independent set of the same stuff for my downstairs. The downstairs thermostat is set at 74, and the unit rarely turns on. Things stay cool and comfortable, and when it gets really hot outside the system has no problems keeping the whole bottom floor (as well as my basement) cool.

My upstairs on the other hand NEVER gets cool. I have the thermostat set at 71 (which still feels significantly hotter than the 74 degree setting in my downstairs). The unit NEVER shuts off, and even on days when it's only 75 degrees outside, my upstairs is still uncomfortable. Also, on days when it hits 95-100 outside, my upstairs never gets below 75-78 (which to me is unbearable) and the unit just never stops running 24x7.

I have an attic with tons of insulation, a ridge vent, and 3 gable vents. My house is far from a mansion (2000 sq/ft if I'm lucky), so I'm trying to figure out what to do.

Oh yeah - and aside from the uncomfortable temp in the bedrooms on my top floor, my studio (which is a small closet off of my bedroom) is always 10 degrees hotter than the rest of the floor (even with all of my gear powered off).

Any ideas? Some people have recommended gable fans, but I can't imagine needing more ventilation in my attic since on cool days, I can actually feel outside air flowing in through the ridge and the gable vents (and hot air on hot days...). It's hot in the attic, but not 230 degrees hot.

Any opinions would be welcome. To be honest - I'm almost at the point of ripping out my entire upstairs system and starting from scratch. It is driving me so NUTS, because not only am I not comfortable upstairs where I spend 99% of my time, but my cooling bill is fucking outrageous.

Oh yeah - the heating system has zero problems keeping my entire house comfortably warm all winter...

Thanks,

Bobby

 

[Dalinkwent48@aim.com]

Might be a stupid idea but it worked for me, close the vents downstairs. It MIGHT help push some of the cold air to the top floor and cool it off a little bit.

 

[Copper_head]

Initially I would suspect the ducting on the upstairs for the uneven temperatures, also what size are the units and how many square feet is the upstairs/ downstairs?
Where are you located?

 

[rlcramer]

The 2 units are 2.5 ton Trane XR-13s. Each floor is about 1000 sq/ft.

I'm in NY about 20 miles outside of Manhattan.

Thanks for any help you can provide.

Bobby

 

[Wolfeman]

Are there air-returns on the upstairs rooms?

 

[53Crëw]

I take it one unit is for the upstairs and the other is for the downstairs/basement?

If so, perhaps the freon needs to be recharged for the upstairs system? (Freon leak?)

I was going to also suggest more insulation upstairs, but it sounds like you got that covered.

If the house if very old, you might have poor insulation in the walls and the heat may be coming through the walls and not the attic.

Reflective window film on the sunny side of the house can help reduce heat coming in through the windows.

I don't recall the number, but if the air temp coming through the vents is "X" degrees cooler than the room temp, it tells you that the AC is working correctly and that the problem lies in the insulation. Perhaps a google search on AC inspection might reveal the number. Can't remember because it's been quite a while since I've had mine inspected.

Wolfeman has a good point as well...

 

[Copper_head]

'K
5 tons of air for 2000' might be little bit light by my local AZ standards, but should be fine in NY.
Split temps are 20 degrees, point an infrared thermometer at your return and at the vent, should be 20 degrees different.
I'm guessing if it's electric heat, there are heating grids in the air handler as I don't think a heat pump would keep you warm enough in your locale.
Looks like to me if the split is OK, this means the air conditioner is running right, you're going to have to get in the attic and make sure it was insulated correctly AND ducted correctly.
Of course, make sure your filter is clean, change monthly.
No need to buy fancy or expensive filters, a cheapo changed monthly does the job fine.

 

[rlcramer]

Thanks for the info so far guys.

I have a single 14x14 return in the upstairs. Could this be the issue? I know some houses I've seen have multiple returns per floor. I also have a single return on my first floor - 24x16 or something like that. But again - only one for the entire floor.

The attic was renovated in 2006 with 8 inch fibreglass insulation throughout. I made sure it was puffed up all over, so I don't think that's the issue, but I'm a bit of a noob at this stuff, so I really don't know. The upstairs walls are all newly insulated as well.

Bobby

 

[Copper_head]

One inlet is OK.
Your air handler for a 2.5 ton condenser unit should have a 16" duct. That's about 201 square inches.
Your filter is 196 square inches, so that's OK but make sure the filter is kept real clean or your efficiency and air flow are gonna drop real fast.
Check the split temperatures to make sure the unit itself is working OK.
The return should be sucking pretty hard, and I'm guessing the runs to the vents upstairs are fairly short so they should be blowing pretty good.
You can go into the attic and make sure that insulated flex duct was used, no duct has anything laying on it or is restricted, and that everything is taped securely with no air blowing in your attic, or that the inlet is not trying to suck attic air.

 

[rlcramer]

Thanks copper_head - I'll give all that stuff a check this weekend.

I appreciate the help.

Regards,

Bobby

 

[EerieVon]

I am no expert but heat does rise and you may want to consider moving the thermostat to the upstairs

 

[Copper_head]

So how did it go?