Humidistat vs thermostat

I'm in south Florida. One of my seasonal neighbors just came down for a taste of our summer conditions. In his new house here it appears that the humidistat and thermostat are in series. That is, if either is satisfied the a/c does not come on. In his previous house it seems that they were in parallel. If either was not satisfied the a/c came on.
Which configuration is preferable and what is the reasoning behind the choice.
I have an opinion, but I am looking for informed, professional answers.
Thanks,
Charlie
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the
I think you meant:
Series: if either is NOT satisfied the a/c does not come on. Parallel: If either (or both) IS (ARE) satisfied the a/c came on.
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the
Of course, you're right
If this wasn't a written note but a spoken message I could have used the old line, "My tongue got in the way of my eye tooth and I couldn't see what I was saying."
Anyway, I am still searching for the answer to the right question
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a
satisfied
what
IMHO,
I'm afraid he talked you into being wrong about being right......
Series: If either stat is satisfied, a/c won't come on. Parallel: If either stat is not satisfied the a/c will come on.
Satisfaction for a thermostat would be when the temperature (humidity for the DEhumidistat) set point is reached and it is no longer calling for cooling (or dehumidification). This would mean that a satisfied thermostat is a switch in the open position and a calling thermostat is a switch in the closed position. When in series, if both stats aren't closed - the circuit isn't complete. Both must be calling, therefore if either IS satisfied - the circuit will not operate. When in parallel, if either stat closes it will complete the circuit. Either stat can be calling to operate the circuit, therefore if either stat is NOT satisfied (closed) the circuit will be complete.
Are you satisfied? :-)
BTW, your answer to the right question has been discussed and many feel that it's a matter of personal comfort and preference, especially factoring in local climate. Since your friend has experience now with both methods, I'd have to recommend that he pick the one he likes best.
- Robert
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I to live in South Florida & a lot of residences have a humidistat & T'stat wired in series. While I myself am not a believer in this a lot of people are satisfied with this application & thats where it's at, Black cars & White cars one has a choice.
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the
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I'm a believer. And I have mine in series. Both conditions need to be met to enable the A/C contactor. The arrangement enabled me to reduce my electric bill considerably, keep my wife from having a dry throat in the morning, keep my mother from having to use "Artificial Tears" in the morning, and no more mold in the bathroom. When the bathroom door opens after a shower, the sensor causes the A/C to kick on within 40 seconds. Stays on till the bathroom is clear. Makes it easy to catch a bit of extra cooling coming out after cutting the grass, etc. I just come in, breathe on the 'stat, and sit in a chair near a duct opening. The A/C will run for several minutes. I keep my thermostat at 73 degrees, since you can have a comfortable 83, or a balmy 73. Sure beats the days of keeping the thermostat setting at around 78 for budget reasons.

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I rewired an Aprilaire humidistat so that it 'makes' on humidity rise, rather than fall.

the
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Never seen an AA humidistat that had more than 2 terminals, and those weren't interchangeable....

a
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Sorry, Heat Man. You weren't looking. Open one, look again. The switch has three connections, only two wires. Solder a piece of stranded wire to the unused terminal, snake it out along with the connection wire from the 'common' terminal.
I have one on my A/C, another on a bathroom vent fan.

for
that
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the
We live in southern FL most of year, and having found that most of the "informed" professional answers were all over the map, I just decided to hook up a humidistat in parallel with the thermostat, and after playing around for while left the humidistat at 65% and set the temperature at what ever feels most comfortable. When away for extended periods in the summer, keeping in mind the mold problems we have down there, we set the temperature at 85-87 and leave the humidistat at 65. Has worked out very well for us over 17 years in two different condos.
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This is Turtle.
There seems to be a little confussion here so here you are.
The Humitistat or the thermostat should be able to turn on the hvac system by theirself without the other being call for cooling. This is will be only for DeHumification or during the summer time when cooling is needed.
Now you say if the humitistat or the thermostat are hooked up in series that is wrong and you could burn up if the humitity was right but it was 120F in your house. The unit would not come on. For in Cooling mode the Humitistat and Thermostat should be hooked up in Parallel to have either turn on the system as need be.
The Humistat or the thermostat should be able to turn on the cooling at any time. TURTLE
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Thanks Turtle, that was always my idea. The guys who did the installation of the a/c in the new house did it the other way and that didn't seem right.
Charlie

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I understand the concept, and I understand what you're saying, but I'm puzzled about one thing... If the humidity is high enough to trigger the a/c, but the space is already as cool as desired (say 72 degrees), what prevents overcooling of the space?
--
Wayne in Phoenix

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This is Turtle.
Nothing but your going to get your ass Cold till the RH% is satisfied.
Now there is better ways to do this with a electric heat strips that will add heat to the system to prevent the over run of a cold house till the RH% is hit but this is very expencive and not cost effective at all. Johnson Controls can set you up a very good system like this for a mear $40K or so.
TURTLE
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That's what I thought. So one could ideally create a perfect combination of humidity and temperature, but potentially at a great cost.
My dad was an HVAC engineer and, while I didn't gain a huge amount of knowledge from his, I do remember his saying that if an a/c unit is properly sized and installed, it will maintain the closest ideal tempeature and humidity.
--
Wayne in Phoenix

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Hi Wayne, hope you are having a nice day
On 22-Jul-04 At About 16:37:31, Wayne wrote to All Subject: Re: Humidistat vs thermostat
W> My dad was an HVAC engineer and, while I didn't gain a huge amount of W> knowledge from his, I do remember his saying that if an a/c unit is W> properly sized and installed, it will maintain the closest ideal W> tempeature and humidity.
Exactly, if the system is sized properly you don't need anything other than a thermostat.
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