Mortimer Schnerd, RN wrote:

wrote:

In an amazing coincidence, F degrees = R degrees - 460... and "ln" is
the natural log, the inverse of the "e-to-the-x" key on a Casio fx-260
solar scientific calculator ($8.76 at Wal-Mart.)

Thanks, that cleared it right up!

You are welcome. Now what's the dew point above with 60% RH?

You got me. 23?

Nonono. The dew point temp goes UP with increasing RH.

You DO have a Casio fx-260 solar scientific calculator, no?

Td = Ta/(1-Taln(R)/9621), approximately, with temperatures in absolute
Rankine degrees...

R degrees = F degrees + 460.

and RH R in fractional form...

R = RH/100.

For instance, 70 F (Ta = 70+460 = 530 R) air at 50% RH (R = 0.5) has
Td = 530/(1-530ln(0.5)/9621) = 510.5 R, ie Td = 510.5-460 = 50.5 F.

With RH = 60%, R = 0.6, so Td = 530/(1-530ln(0.6)/9621) = 515.5 R,
ie Td = 515.5-460 = 55.5 F.

Nick

PS: The price of a standard basement Humidex is $1095, installed.
Loren says they have a 1 year performance guarantee, ie you
can get your money back after 1 year if you don't like it. And
she says it works better in houses with AC. But moving air from
near the basement floor upstairs would be more efficient than
moving it outdoors and moving more outdoor humid air indoors,
in a house with AC.