Rich wrote:

You are somehow going to magically evaporate 2.62 lb/h of water...
I want to know what apparatus will do such a thing...

A portable swamp cooler near an open window comes to mind, or some
Humidifalls (tm) with the heaters turned off, or a rock cairn with
a $10 10 W fountain pump in a corner or a few toilet tank fountains
or an indoor greywater wetland or (my favorite), a concrete slab.

My PA neighbor has a 20-year old basement slab that was probably placed
with no vapor barrier underneath, unlike present practice. The water table
is high (my old hand-dug well has water 9' below ground) and water seems
to be moving up through the slab and evaporating into basement air. We
never see puddles or damp spots on the slab. The gutters and downspouts
are in good shape, but after 3 blower-door tests and air sealing, the house
air is never less than 60% RH in wintertime, even with a bathroom exhaust
fan in series with a 60% humidistat. It's probably time to paint the slab.

...An A ft^2 pool of water loses about 100A(Pw-Pa) Btu/h by evaporation,
where Pw is the vapor pressure ("Hg) at the water temp and Pa is the vapor
pressure of the air around the pool (ASHRAE)

Pw = e^(17.863-9621/(80+460)) = 1.047 "Hg and Pa = 29.921/(1+0.62198/0.012)
= 0.566 "Hg, so each square foot of 80 F wet surface will evaporate 48 Btu/h
(about 0.048 lb/h), if it's only exposed to house air. In that case, we need
about 2.62/0.048 = 54 ft^2.

I can imagine a 50' soaker hose in series with a solenoid valve making
a 1'x50' perimeter strip of slab dampish. A new house might have plastic
film on the caliche, under stone, under concrete, with a hole in the slab
for water to enter and flow under the slab.

Cooling thermal mass directly is more efficient than cooling air that cools
mass, and a cool slab with a ceiling fan and a room temp thermostat and an
occupancy sensor might allow good room air temp control with a cooler slab
with a larger temp swing that stores more coolth and allows effective "AC
setbacks" when a room is unoccupied.

Nick