udarrell,
This original poster's question was very simple and asked how a humidistat
could possibly be used to save air conditioning cost / lower electric
consumption by cycling the a/c based on humidity as well as temperature. The
incorrect reply someone offered was that a parallel connection of humidistat
and thermostat was all that was needed, and the lower of the two setpoints
would then properly control the air conditioner.
I raised the concern in my post that merely connecting the two controls in
parallel would not work. This is very simply because a standard humidistat
closes its' contacts when the humidity drops, and thus, in a parallel
arrangement someone else suggested, switches in the exact opposite sense
from the desired opening of its' contacts. As the humidity dropped, the
humidistat would continuously call for more cooling, and the a/c/ would run
on wasting huge electricity and over cooling in the process.
The subsequent "improvement" to this approach offered by someone else was to
then add a relay and power source, to invert the humidistat switch closure,
so that dropping humidity which closed the humidistat would then open a set
of relay contacts. This would indeed correct the original design mistake
originally made by whomever offered it.
I replied to offer the suggestion that a Honeywell dehumidifier control such
as the one I cited at Amazon would switch correctly, and avoid the need for
a relay or additional power altogether. In fact, this type of
dehumidification control is designed specifically to switch a system "OFF"
when the humidity level is lowered, exactly what is needed in this case.
This was NEVER a discussion of room heating thermostats, or had any
reference whatsoever to what could or should be done in a more complex
system with a furnace, humidifier, etc. You are certainly correct that
****IF**** the original question were to be asked as to how to configure a
thermostat and humidistat for all season control of furnace, humidifier, air
conditioning, etc., then a different approach would most certainly be
warranted.
This was, however, not the question which was originally asked. Nor were the
replies intended to answer this different question.
Smarty
question and discussion never asked about heating. It asked about how to
control air conditioning using both a thermostat and a humidistat.
"udarrell" wrote in message
et...
Smarty wrote:
Wiring the humidistat and thermostat in parallel should theoretically
work, but.............
most humdistats... -
(That is a Dehumidifier "DeHumidistat" for the Cooling Mode, "Not the
Heating Mode Humidifier Humidistat.")
- ... are designed to *********close********* their contacts when the
humidity falls below a specific set-point (so as to energize a humidifier)
and therefore, will *******do the opposite******* of what the original
poster intended******* if wired in parallel as recommended.
The room TH has two Modes - Heating & Cooling, in the cooling mode, wired
parallel, the circuit would stay closed until the Setpoints of both
sensible temp & % RH were met.
In the Heating mode the Humidistat contacts would work the opposite way &
close to bring the humidifier on when the RH got too low.
Because Heat & Cool are separate circuits', each separate circuit can be
"wired in parallel to do different or opposite things.
The Humidity controller in each separate circuit is engineered to perform
differently, in the Heating Mode the Humidistat contacts are open until
the low %RH setpoint is reached & then the contacts close bringing on the
humidifier. The "Cooling Mode Dehumidification controller & circuitry"
works the opposite.
If they are wired in series, as soon as one of the two setpoints' is
reached the control circuit to the contactor in the cooling AC mode would
open shutting it off before the other setpoint was reached. The entire
purpose is to keep the AC running until both comfort level setpoints are
reached. The setpoints of the individual RM TH & the dehumidistat can be
set at a point where the individual wants each one for their desired
comfort in either the Cooling or Heating Modes.
There should also be a differential settings on both setpoints so the
controller can eliminate short cycling, especially of the AC in the
Cooling Mode.
http://www.udarrell.com/air-conditio...tent-heat.html
- udarrell
What is actually needed is a humidistat which closes it contacts when the
humidity level *****rises***** above a specific set-point,. thereby
energizing the air conditioning when there is too much humidity.
Using a conventional humidistat as the prior reply indicates will ***NOT
WORK*** as claimed, and, in fact, will turn on the a/c and keep it on as
the air gets drier....... Smarty
Sorry Smarty, but that is NOT the way the two separate circuitry's of
separate Heating & Cooling Modes will be wired. (See Above.)
- udarrell
"udarrell" wrote in message
s.net...
1D10T wrote:
I read that if you set the T-stat to 70º and the H-stat to what you
*perceive* to be a comfort level, the AC only runs to achieve the
relative
humidity set on the H-stat. It went on to say that it helps to keep the
unit
from cycling as often as it normally would, thereby saving electricity
and
still be comfortable. The THI here for a week has been 110 - 115, and it
just got me to wondering. As inexpensive as the H-stats are I thought it
would be worth a try - or at least the time it takes to do all this
typing.
:-)
Opinions appreciated!
TIA
- - - - - - - - - - - - - - - - - - -
Easy's gettin' harder everyday
The two controls are wired in parallel (Not in series) therefore, if
either the Temperature or the %Relative Humidity set points are Not met,
the AC contactor will stay energized & the AC unit will stay running.
Especially if the system is somewhat oversized, it is a good way to go. -
udarrell
--
WISDOM PRINCIPLE DIRECTED EMPOWERMENT COMMUNICATIONS - THE REAL POLITICAL
ISSUES and WISDOM BASED PEOPLE EMPOWERMENT
http://www.udarrell.com/my_pages2.htm (* My Airconditioning Links, Hunting
Shooting, Angus Cattle, etc.)
Reality Is Not An Easy Thing To Be Confronted With, or to Accept!