a/c vs. the sun

I moved into an apartment in January and wasn't giving a/c too much thought; I should have. I'm in a suburb of KC on the top floor, flat roof, 1 bedroom, probably about 850 sq. feet.
The sliding glass doors get blasted with the afternoon sun living room faces west. I put up "supposedly insulated" draperies. Things weren't too bad until about 3 weeks ago when the temps really soared and the sun has been relentless. The entire side of the apartment has no windows, but faces south.
The ancient no-name a/c does OK until it hits the mid 90's and if the sun is shining all day, by about 3pm the temp in the area towards the sliding glass doors is 83 and 80-81 in the interior. It helps a bit to shut off the vent to the bedroom (and shut the door) until the evening to try to force a little more towards the "sunny side" but even at that, if it's a 93-100 degree day, and the sun is shining all day, the a/c runs continuously from about 10-11am until 7-8pm, then cycles (and cools) very well even on recent very hot nights. If it's a cloudy day, there is no problem; the a/c cycles all day, maintaining 75 with no problem and seemingly not a lot of run time. This is my first summer here and I don't know the climate, but I used to live in the Washington, DC area and remember some top-floor garden units having the same problem.
The weather has moderated just a bit, down perhaps 5 degrees, resulting in 78-81 in the living room with the a/c running nonstop until sunset where it quickly attains 75.
The engineer here says the a/c units are old, undersized, and there's nothing I can do. He says they are 1 1/2 ton units, probably very, very old. There is no question that the a/c works under reasonable conditions, but it seems to really lose it past a certain point. I'm used to living in apartments since the 70's that had individual heat pumps, and they seemed more resilient with extreme temps; this unit is still cooling on these hot days, but either due to the extreme heat load from the sun/top floor/flat roof/etc. OR the vintage equipment, it has to run a lot to keep it cool. He says the unit is functioning as well as it can, pressures checked and all that. I did what I could as a "tenant" - I was amazed to see the electric furnace/ac coil on top unit tucked into a little closet with a bifold door with tiny slits that can't possibly pass enough air, and in fact the unit rumbled and got quieter when I just started leaving the door open a few inches. I figured that another bad thing about starving it for air is that it would pull more from the small but still-there spaces around wiring/duct/refrigerant lines going up through the ceiling... that it would pull down hot air. The engineer is trying to get me a new bifold door with real air intake vents on the bottom (furnace built up on a wooden platform, draws air underneath from the front).
So the bottom line is the engineer says this is the best I can do, my electric bill will no doubt be tremendous next month. I'm having some health problems, and my landlord is looking into "waiving a move charge before my lease is up" to another unit in the complex. Should I expect more from the a/c or was I spoiled by the shady trees and powerful heat pumps back east?
Thanks - Bill
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Sounds like it is marginal at best and since you are on the top floor, probably a bit undersized if all units have the same size. Aside from keeping the sun out, not much you can do to boost the output.
Judging from my own house, that 1 1/2 ton is adequate to the high 90's where I am, but I'm much farther north and not getting the sun as much. Perhaps better insulation under a peaked roof too.
As for the electric bill, you need a given amount of power to run a unit of that size. If you went to a larger size that cycled more, it would still take at least the same amount of power to run it enough to cool the place. Some units are more efficient, of course, but size is not the only factor here.
If you need more power during the day, consider adding a window unit to get a little more cooling. From your description, it would only be needed during the day a few weeks of the year. A 6000 Btu unit will top the scales for you.
--
Ed
http://pages.cthome.net/edhome/



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Without a complete set of readings, every thing would be a guess. But one thing is for sure, the return air set-up isn't up to code!
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Static convection causes Hot air to rise and a stack effect which places the maximum load on the top floor. The flat roof and windows adds to this with additional solar load Outside air ( Fresh air ) is a major additional component and this can be checked and perhaps adjusted.. Keeping the RA Filter clean will reduce the Latent load on the Unit and maintain capacity

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You have to stop the heat BEFORE it comes thru the glass. We have the same setup with 2- 6' X 6' windows on our deck that get direct sun from dawn intil 1 PM. Every day, by 9-10 Am it was very hot in the room We went to Lowes and bought some roll down shades. They only cost about $ 13.00 each IIRC/ They're white plastic thin hollow tubes (used to make them out of strips of bamboo or cane but the white plastic seeems to hold up better. I hung 3 angle brackets over each window and wired the 3 hangers on each blind to them. Each AM, SWMBO goes out and rolls them down. It stays probably 10-15 o cooler in the room now and we dont have to put the "air" on til much later in the day.
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Hail Storm wrote:

I wonder when your AC unit was last cleaned professionally. It can improve the performance of any HVAC unit by quite a bit especially if has gone a long time between cleanings. My guys and me recommend cleaning once a year for a home AC and twice a year for a commercial AC or any heat pump. The amount of dirt that comes out of a unit would surprise you.
[8~{} Uncle Monster
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wrote Re a/c vs. the sun:

Sounds like the a/c is functioning ok, but too small for the heat load.
How about a couple of small window a/c units? They are cheap and could provide supplemental cooling when/were you need it.
--
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Thanks everyone for your responses. I have to conclude that the a/c unit for my apartment is old, undersized, but it's still working, probably as well as it can. It doesn't go into the continuous-run questionable-performance mode unless the sun is scorching this apartment, and this place was built in 1969, and I'm not so sure insulation and things like that were a big concern then for apartments. Back east it seemed like in 1969, half the projects had "central" (boilers and chiller) heating and cooling, half had small individual gas furnaces/electric individual a/c. I know of some places where people on the 3rd (top) floor, on the "afternoon side" were pretty miserable during much of the summer. One in particular the third floor tenants would often have 85 degree days inside, with a/c running. Now a lot of developments have gotten rid of their boilers and chillers, stuffed air handlers/refrigerant coils in the small "utility closets" that were used during the "chilled and heated water" days (which were lousy for spring and fall) and put heat pumps either on the roofs or on the ground and run refrigerant lines into the units (along, of course, with major rewiring and individual electric metering). I thought that was a pretty good way to go, except that the developments had pretty bad single-pane windows and no insulation. The place I lived at before moving out west replaced all windows with really nice double-pane windows, and I've been told several developments in the area (suburbs of DC) have replaced windows to go with the individual heating and cooling.
Out here heat pumps are scarce in the garden apartments I've seen; perhaps because the temperatures can be rather extreme. For heat - there are a lot of just plain resistance-heated apartments, some gas, (lucky me, plain electric, I think it draws about 8 KW); my winter electric bills were not bad at all probably thanks to the contribution of the sun (which is now paying me back with the lame a/c and no doubt next month's bill will be off the charts). Here the apartments are in "various states" - some have double pane windows, most do not (mine does) and most don't have weatherstripping (!) on the door to the apartment (it's a huge hallway, not exposed). Mine does have weatherstripping, the only one in my stairwell. A former tenant must have b*tched about it. The "model" has a decent bi-fold door with air intake grilles on the bottom; the few "real apartments" I've seen are like mine, equipped with a "decorative but not meant as an air intake" door with small openings.
After living in heat-pump equipped apartments since 1977 it was a shock (no pun intended) to see this place with a "plain electric furnace."
YES the idea of a window unit for an "assist" during the hottest days would be great. However, being an apartment with the usual apartment rules (they all seem to read from the same manual) I'm not allowed to have anything hanging from the windows (small window shaker). The only thing I can think of then is to use a portable, and I even have one - but I bought it in a deep-discount sale at good old Home Depot several years ago (Maytag branded) but I haven't tried it because it's a "single hose" contraption; it would pull conditioned air from the apt., cool it's condensor, and expel hot air out the window vent. I have to wonder how much heat it would bring in to make up that air, though. I did try it once a few years ago and it really didn't accomplish much. Now I realize the twin-hose models are the way to go, but no $$$ for that. Another huge downside is that if I put up the window vent in the usual sliding-glass frame, it would be a huge risk in one of the fierce thunderstorms that pop up (and quickly go away) here though on one of those 'guaranteed 100% sunny scorchers' it would be worth a try.
Thanks everyone again, for your suggestions!
Bill
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The suggestion to use outside shades is very good where you have a lot of exposed glass.
Don Young
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Don Young wrote:

or some kind of awning? is the balcony roofed or unroofed?
can't hurt to get a much better insulated drapery, either... I'm sure those patio doors are the biggest heat leakers.
Any way to make the roof greener?
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"> or some kind of awning?

The balcony doesn't have a roof. Few garden complexes in this suburb do; yet where I came from in the suburbs of Washington DC very very few balconies were built without roofs.
I'm told the roof is a very light shade of gray, almost white. I haven't seen it myself. I'm still searching for some kind of white opaque material to just plain block the sun. The draperies are insulated, but even though they cost a fortune and I specified they were to keep out the sun, they only do so much. I can't put out any awnings (too much wind, for starters) or any material outside the window, as that is a big lease violation.
Looks like I either have to move or somehow build the translucent material I can throw in front of the drapes when the sun is baking the apartment. One nice thing I'd lose by moving to another unit here is that the end wall isn't shared, so there really are no noise problems, and the floor is concrete (big surprise since everything else here is wood) so probably the only thing that might irritate my neighbors is a subwoofer.
Just 20 feet away is a HUGE tree that shades another group of apartments, I'm sure they have it easy in the summer, but there is a downside when you have a flat roof with inadequate drainage - all the leaves and junk from the trees clog up what drains they have (and there are roofs that leak, though not mine so far).
Thanks for all the great suggestions...
Bill
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I use vertical blinds, sheers, and heavy insulated drapes. Still, some sun gets through but the blinds help a lot.
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Something reflective next to the glass, along with insulation, might help. Aluminum foil taped to the glass would be easy and might be a useful test even if you do not like it long term.
Don Young
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