2 tons of fun

[thurston]

my 2 ton a/c on a 95 degree day can keep my house at 75, but the humidity won't go below 62. Is that normal? Is it too big? The humidity outside is only 50. What's up with that?

[beenthere]

Thats possible.

Are your ducts sealed.

Is the blower on high, when it should be on med, or a lower speed.

[duct dr]

Sounds like you may be drawing air from the attic. Have the duct work checked for leaks.

[wyounger]

Does it run constantly through the afternoon and evening when it's 95 degrees? It shouldn't have enough capacity to cycle off on a day that hot.

If not, it may be too big. We're talking about a smallish semi-detached (think two story duplex, Americans) in Ontario, probably very well insulated and with a big common wall. 1200 square feet, I seem to remember, thurston?

Also yes, could be related to return duct leakage, or the indoor unit could be set for too much airflow during the cooling mode. Are we talking about your old system, or have you gotten a new one yet?

75 degree air can't hold as much moisture as 95 degree air. If the system doesn't remove enough moisure as it cools the air, the relative humidity will be higher inside than outside any time you're using the AC.

[Panama]

If you can, lower the blower speed a notch and see what happens.

[operator]

Originally posted by duct dr
Sounds like you may be drawing air from the attic. Have the duct work checked for leaks.

if ontario its unlikely he haxs ducts in the attic, systems are run from the basements

[slice]

So you are saying Humidity in the house is higher than outside, Hmmm do you shower and turn on the exhaust fan in the bathroom > or open a window to let out that steammy humidity ? I notice that 90 % of people do not and where does it then go >? makes the a/c work harder to remove it..

after showering leave the darn thing on for 15, 30 minutes,,,

[tuccillo]

Originally posted by thurston
my 2 ton a/c on a 95 degree day can keep my house at 75, but the humidity won't go below 62. Is that normal? Is it too big? The humidity outside is only 50. What's up with that?

In terms of absolute amount of moisture in the air, 75F with 62% RH is much drier than 95F with 50% RH. RH is a very misleading quantity because of the temperature dependency. Dewpoint is a better measure of moisture - specific humidity ( gms/kgm ) is my prefered measurement.

[operator]

good call tucillo