On Aug 6, 11:23 am, lagman wrote:
All,

I'm trying to decide whether or not to invest in a de-humidifier. I
just bought a house with a finished basement (first house I have ever
had with a basement). When we were looking at the house, I noticed
the previous owner didn't have one in the basement. I think it is
comfortable, but my wife thinks it feels too humid (we have had a
couple weeks of very humid weather).

My main concern is mold growth. I am going to put a hygrometer down
there to measure the humidity. At what level should I be concerned?
I should also mention that once our furniture gets here, it will
contain a big screen LCD TV and some stereo equipment (I'm not sure if
a humid basement can damage electronics or not).

If I do need one, is there any advantage to putting a lot of money
into one of these things? I see a 25 pint model at Lowes for $139.

Thanks,
Dan

In fairly cool climate with only a couple of months of warmer moister
weather; we have a basically unfinished below ground basement,
concrete walls, mainly used as a workshop. Also the washer and dryer
are down there along with the hot water tank etc. It stays pretty well
at a ground temperature of about 60 deg. Fahrenheit hardly ever
dropping below 55 deg. F. even in mid winter. It is heated only when
we are down there working on something.

During this warmer more humid weather some of the outside air
inevitably gets into the basement and since it is cooler raises the
relative humidity.

We a have low cost dehumidifier (IIRC it was about $150) running
continuosly at this time of year. Currently it is removing several
litres of water per day which serves to avoid dampness and/or slight
rusting of our tools.

As the outside gets cooler any air getting into the basement will be
cooler and our dehumidifier will run less often

If you intend to live in and heat the basement you may not need to
dehumidify. Might also depend on your heating system. Hot air oil
(gas?) furnaces used to be common and often incorporated humidifiers.

Raising the temperature even a few degrees, usually by means of an
electric heater, can drop the relative humidity quite dramatically.
Warmer air can 'hold' more , moisture.

That heating technique was quite often used in tropical countries
before the common advent of air conditioning to avoid dampness in
telecommunications equipment. Tube type radio equipment used before
the common availability of transistors usually generated enough heat
to keep itself dry. As computers, radios and and TVs have got more
'efficient and if rarely used, they use less electricity and so,
sometimes, may be more liable to absorb moisture into their
components.

The idea of using a hygrometer is a good one. If you get to the stage
of mould you could get problems, possibly health and structural!

Note; We once had the air conditioning fail in a telephone equipment
building; it was also raining continuously. Borrowing a hygrometer
from the local university we took various measurements. No problem at
all; the heat from the switching equipment was raising the temperature
by more than enough to keep relative humidity e well below unsafe
levels.

What would have worried would have been if the power failed completely
and the whole building cooled down so eventually dew could have formed
on the equipment!