A year ago, I had Muns install a dehumidistat while I was up north for the summer. Then this past June when I was getting ready to leave again, I turned it on and tested it but found that it wasn’t working, so I called Munns.

The electrician found that it had never been attached to the thermostat. Apparently the previous electrician (who no longer works for Munns) found that a stud was in the way and figured nobody would know the difference if he never actually hooked it up. So I recommend that you test yours, and here’s how:

Set the dehumidistat to the on position and then slowly turn the dehumidistat dial towards 80. As soon as the dial reaches a setting that is higher than the current humidity in the room, you should see the LCD panel on the thermostat go blank because the dehumidistat has cut off the power to the thermostat and you know all is working as it should.

Having installed a couple of furnaces, humidifiers on furnaces and air conditioners, let me assure you that humidistats control humidifiers and dehumidistats control air conditioners.

Could you recommend a product for me? I've only found the ones that call themselves humidistats. I want to install the right one.

Thanks,
Russ

My last trip down, our A/C went out. Brand new house, closed Sept 2 and the A/C went out :mad:. I called the warranty department and they sent the company that installed my heat / air and found the freon was 2 lbs low. He charged it and adjusted some kind of pressure thing and said if it happens again, they would run some kind of leak test. While he was there, he showed me a new thermostat that has the de-humidistat built in. I thought what a nice feature until he told me the price of $ 329.00 installed :shocked:. I about fell out. I told him if I decide to move forward, I'll call.

I didnt mean for it to be such a subject, but.....it seems a lot of people dont know how to operate these switches, I think I have gotten the truth of the matter though

I wasn't confused, or so I thought. I was wrong. :undecided:

p.s., Handie-- nice to see you posting again!

question
 

Should the dehumidistat be wired in series with the thermostat or parallel? Specifically when used not for comfort but to save energy during unoccupied periods.
Thanks

Wrote this in a previous thread on the subject:

The thermostat probably has four wires: Red(low voltage line), Green (Fan relay), White (Heat relay) and Yellow (Cooling contactor). To wire in parallel, simple attach one of the dehumidistat wires under the yellow wire terminal(with the yellow wire) and one of the wires under the red wire terminal(with the red wire). Now your air conditioner will run if either the relative humidity rises above the setting you establish OR the temperature rises above the thermostat cooling setting (even if the relative humidity does not reach the setting you establish).

If you wire in series, you would disconnect the yellow wire and attach one of the dehumidistat wires to it with a wire nut and attach the of other dehumidistat wire to the terminal where the yellow wire was. In this situation, the air conditioner will run only if both the relative humidity rises above the setting you establish AND the temperature rises above the thermostat cooling setting. If the thermostat setting is not low enough, the air conditioner will stop running before the relative humidity desired is reached.

In either case, you probably need about 2 or 3 foot of 18/2 thermostat wire since the dehumidistat wires will not reach to the thermostat. Wire nut the thermostat wire to the dehumidistat wires to extend them to the tstat.

Check this site:

http://www.rancoetc.com/manuals/j10-809_wiring.pdf

It mentions things to consider when wiring in parallel and in series for a dehumidistat.

IN ALL CASES, MAKE SURE YOU TURN OFF THE BREAKER FOR THE AIR HANDLER before touching the thermostat wires. You do not have to turn off the compressor breaker.

Good luck.

BTW, I wired mine in series because I wanted the humidity to control the air conditioner and not the temperature when I am away.

Thanks, for unoccupied series settings, what do you set the temp at and what RH setting? thanks

Munns installs these in series and recomends 78 temp and 60 RH when unocupied.

Russ

Be careful if you buy the combination unit above, it is used to control a furnace humidifier in order to increase the humidity in the house during the heating season. It does not work with the air conditioner to maintain a certain humidity level during hot humid weather.

edvin, will the munns unit keep the house at 78 degrees when you are gone, if so I hardly think you would have any use for a humidistat, i keep my thermostat at 80 degrees when I am here....gn

Thank you!

There is only one reason to install the humidistat in your Florida home, and that is to limit the AC running when not there. Mold cannot form unless the humidity is above 60% and the temperture is about 85 degrees. AC keeps the humidity below that and does not allow it to form. So by setting the AC at 80 degrees, the humidistat at 55% or 60%, the AC will only come on if the humidity becomes high and remove the humidity. I have returned to my home in the summer and the house is 90 degrees plus inside, but low humidity below the 55% where I leave that set. So no, it does maintain a cool home while your gone. It only runs the AC if the combination of high humidity and high temperature occur at the same time.

Much different then the humidity control I have on my home in Virginia. That is there to add moisture in the winter when the air is to dry.