Dave Gibson wrote:

does a portable unit which says keep doors and windows closed expel the
heat?



Latent heat of evaporation of water. Room gets cooler, air gets damper.

You get the same effect if you drape wet socks over a fan.

Errr No ;-)

The portable units have a large flexible vent pipe like a tumble dryer -
you poke this out a window or through a vent as Andrew says below. If
you use a window then you want to open it only enough to accommodate the
end of the vent pipe and then preferably "fill in" the rest of the gap
(use a towel or wrap the curtains round the gap etc - some units even
come with foam batts designed for the purpose)

They will condense lots of water out of the air as well - most have an
internal reservoir that needs emptying from time to time. Some you can
connect a hose to if you can find a way to have the water run down hill
to a suitable exit.


--
Cheers,

John.

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