When we lived in Taiwan almost twenty years ago we had Hitachi
computer-controlled window/hole-in-the-wall air conditioners with a
"dehumidfy" mode. In this mode they would run for a while then stop,
then repeat the cycle, irrespective of the temperature. I don't recall
what the on/off ratio was, and I don't think it was adjustable. Would it
not be possible to cycle a typical central air system in the same way to
reduce the humidity without necessarily reducing the temperature by much?
These also had a "night-time" mode, in which after 4 hours they would
raise the temperature by half a degree (Celsius) every half hour. The
idea was that one would not keep waking up because of being too cold.
Have North American A/C systems ever had such a mode?
On Sat, 26 Aug 2006 16:43:56 -0400, "Percival P. Cassidy"
If the condensing coils are outside, then heat will be removed
whenever the compressor is "ON", the rate-of-removal depending upon
the size of the system in tons or BTU's and, to a lesser extent, upon
the outside temperature.
Most residential A/C's are strictly fixed sized units that operate
either in the ON or OFF mode from the sensing thermostat, hence the
requirement for proper sizing to the load. An oversize unit may
bring down the temperature too fast in relation to its dehumidifying
functions. Some of the newer units with variable speed compressors
can counteract this.
Recall that a dehumidifier is just an A/C with its condenser and
evaporator coils exposed to the ambient air. The net heating/cooling
effect is zero, except for the heat added to the environment by the
electrical and mechanical resistance of the electric motors in the
I don't recall any with a "dehumidify" mode, but you can use a
programmable thermostat to do much the same thing on raising the
temperature. We don't generally have the the same humidity problem you
may have had. I would guess most people would just use a dehumidifier if
When we moved into our house, the A/C unit hadn't
been used for years. I repaired it temporarily, but wasn't
ready to replace it till I finished upgrading the ductwork.
But that A/C unit was horribly inefficient, the house had
no insulation, and it was running virtually nonstop.
One night I was in the laundry room when the unit came
on and started delivering into the sump crock. The condensate
was steady for the first half hour, and then started slowing down.
Glancing at the thermostat showed that the temperature hadn't
changed, but it was already more comfortable.
So rather than trying to bring down the temperature, I worked
on simply using the A/C as a whole-house dehumidifier. After
all, a reasonably dry 83 degrees is more comfortable than a
If anyone is interested in knowing how I did it, at no cost other
than my time, let me know by newsgroup reply.
Joseph Meehan wrote:
I would love a dehumidify only setting on my thermostat or even better,
the ability to set temp and humidity levels independently. Add to that
set-back and such and it would save some energy and make things more
someone post that magic link to a supplier who has what we are looking for.
Thanks! I'm reading up on the c3 now.
How about one more feature... A "remote" sensing unit. in other words,
have a temp/Rh sensor in a different part, or parts, of the house. You
set max temp or Rh for all sensors.
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