re: swamp cooler to refrigeration a/c
11 mar 2006
>> james \"cubby\" culbertson wrote
>>> i live in albuquerque and the swamp cooler is ok but not great.
>>> the last few years has seen higher than normal humidities
>>> so at night it struggles.
>>you might try a different configuration with better controls, eg turn
>>on the swamp to cool recirculated house air when the indoor temp rises
>>to 80 f and turn on a small exhaust fan when the indoor rh rises to 65%.
>> this works in melbourne australia...
>few use swamp coolers there.
i too had the impression that melbourne (vs perth) was too humid for swamp
cooling, but i was wrong (have you ever been wrong? :-)
>practically every new house built (and there are a lot of these at
>the moment, most badly designed and over priced) has a large swamp cooler
>mounted on the roof. melbourne is rarely humid. i think the highest
>dewpoint recorded is 23c.
>>> we tried out your split-cycle swamp cooler idea a couple of nights
>>> ago using a jerry-rigged humidistat using a sht11 and a computer
>>> to control the exhaust fan, and the brains of a commercial
>>> refrigerative split-cycle system for the swamp cooler. we closed
>>> all the windows (against standard practice with swamp coolers)
>its a fucked approach with a swamp cooler, nowhere for the
>higher humidity that comes out of the cooler to get out of the house.
reading more carefully, you might wonder what the exhaust fan does.
>>> and ran the swamp cooler to a fixed temp (22c) and the
>>> humidistat to a fixed humidity (65% at your suggestion).
>>> that night it was 28c and 35% outside.
then again, 22c is cool, but comfy (pmv = 0.007), with vel = 0.1 m/s and
clo = 1 insulation. raising vel to 0.5 and lowering clo to 0.5 makes 35 c at
65% comfy (slightly cool, with pmv = -0.54, on a scale from -3 = cold to +3
= hot), according to the basic program in the ashrae 55-2004 comfort standard,
so he might have just used a ceiling fan on that day... 28c at 35% with clo
= 0.5 and vel = 0.5 is "slightly warm" in the comfort zone, with pmv = 0.23.