re: what is best brand rooftop air conditioner?
8 sep 2003
nicolas the great wrote:
>we have a 3000sq foot house and we need a traditional air conditioner.
>not a stinking swamp cooler.
a swamp cooler or some variation thereof should work even better in las vegas
than phoenix. nrel data indicate august is the worst-case month for cooling,
with a 24-hour average temp of 88.7 f and an average daily low of 74.2 and
a humidity ratio w = 0.0073 pounds of water per pound of dry air. this makes
the vapor pressure pa = 29.921/(0.62198/w+1) = 0.3741 "hg and the average dew
point 9621/(17.863-ln(pa))-460 = 48.5 f. with an average (88.7+74.2)/2 = 81.5
night temp, the wet bulb temp twb (r) = 9621/(22.47-ln(100pa+81.5+460-twb))
= 9621/(22.47-ln(578.9-twb)) = 520.5 (plugging in twb = 525 r on the right),
then 522.8, 521.7, and 522.2, ie 62.2 f.
with some thermal mass in the house, you might cool it to 70 f at night with
a swamp cooler or a window fan and a collection of greywatered green plants,
then let it warm to 75 or a dry 80 f during the day, with no ventilation.
we could work out the details, but you seem unlikely to change your mind...