jay wrote:
I bought a Friedrich 40 pint dehumidifier. This has electronic
controls, and I very firmly believe is made in China by L.G.
Electronics (which is the same as Goldstar, and the even Kenwood
Sears units are made by them now).
I have the humidity setting at 45%. I happen to have a separate
digital hygrometer in the basement too. This morning I noticed that
my hygrometer was reading 39%. What I find strange, is that, this
morning the dehumidifier would run with the compressor and fan on
for, say, roughly 10 minutes, and then shut completely off for
EXACTLY 2 minutes and turn completely on again. Then after maybe,
say, another 10 minutes if would shut off for EXACTLY 2 minutes.

It seems to me that whomever designed this thing was trying to be a
bit too clever. Without having seen it in action much I'm assuming
that, instead of simply designing it to behave as if controlled by an
ordinary humidistat, they designed some complicated algorithm so
that, if the humidity gets BELOW the target level, will begin
introducing "2 minute off" periods, and then gradually increase the
frequency of these "2 minute offs" until it stabilizes near the
target. (or alternatively maybe they'll gradually increase the "2
minute off" to, say, a "3 minute off").
Hmmm.....call me paranoid, but....maybe they deliberately chose to
always use "2 minute off" intervals because maybe it's just long
enough not to *overtly* damage the compressor, but short enough a
cycle that it will add more wear and tear so that the unit DEFINITELY
would not last any more than, say, 6 years (the compressor portion of
the unit is warranted for 5 years). In other words, they to short
cycle it so that it doesn't last, say, 10 or 15 years. Am I crazy
for thinking this?
J.

I would guess the 2 minutes off is to allow any frost to melt. The 15%
humidity just sounds like the sensor is not too exact, which is not at all
unusual. I might also suggest that your method of measuring the humidity
may not be all that accurate. Even if it measures a static humidity well,
when it is changing it may well have a delay in recording the change. The
de-humidifier may be responding to the change faster since it has an air
flow to measure.

Generally just about any tool you are going to find, other than wet-dry
bulb is not going to be very accurate.

--
Joseph Meehan

Dia duit