Gas furnace withde humidistat control
 

We are new here and not familiar with how to turn on a gas furnace for heat with the dehumidstat under the control, (dont understand what its for) we put it in the off position? or humistat in on? doesnt feel like we are getting any heat.

Set the humidistat to 0 degrees - On.
Set you thermostat to the desired temperature.
Should work.

Make sure the thermostat is selected for heat.

Thanks, finally figured it out, I put the humidistat on around 30 and the heat kicked in, never had one of those before in my former homes.

I don't mean to be picky, but it really is a DEhumidistat not a humidistat. It works with the air conditioner to remove humidity from the environment, hence the use of the prefix DE. A humidistat would be used to ADD humidity to the environment.

The controller that runs the equipment is generally referred to as the humidistat. The paperwork I received with ours from TV when we purchased our home also refers to it as the humidistat setting. Humidistats can control humidifiers or dehumidifiers.

I disagree, please see the attached link which describes the uses of a humidistat and dehumidistat. Humidistats are not used to control dehumidifiers.

http://www.home-air-care.com/hstat.htm

Found this definition (and more just like it) on a heating and AC site:
Humidistat
A controller that measures and controls relative humidity. A humidistat may be used to control either humidifying or dehumidifying equipment by the regulation of electric or pneumatic switches, valves, or dampers.

You install the humidistat differently for it to control a humidifier or dehumidifier.

Here is the description for the humidistat in one of my houses:
From the Tradeline Products from Honeywell, the H46E-1013 Honeywell Humidistat provides automatic control for a humidifier or a dehumidifier for the best dehumidification in air conditioning systems.

There seems to be no right or wrong answer to this subject. However, I think of it this way.

The thermostat on your wall is a device that measures the amount of heat (thermos) in the air and turns heating or cooling devices on or off as necessary. But we don’t differentiate that functionality by calling it either a thermostat or a dethermostat.

A humidistat is a device that measures the amount of moisture (humidity) in the air and turns humidifiers or dehumidifiers on or off as necessary. So, why is it necessary to have two different names? I prefer to call them humidistats.

Ed, My wife prefers to call it "the thing on the wall that controls humidity when we're not there". Works for me.:coolsmiley:

Yes, that is why the suffix is 'stat'. The prefixes determine what it is monitoring. 'Thermo' for heat and 'Humid' for humidity. They are simple measuring devices and switches that turn their attached equipment on or off.

I would assume that most homes in TV do not have a separate dehumidifier. When the humidistat turns on it simple turns on the AC unit which will dehumidify the air while it also cools it. The humidistat is simply another measuring device to turn on your AC via the humidity level instead of the temp level.

A thermostat can turn on/off a heater or an cooling system. A humidistat does the same with the cooling system.

Isn't this correct?

I am now looking at the card from Munns which was stuck above the thermostat, it says:
"When leaving for an exended period and home will be unoccupied, do the following, set thermostat to 78 and place in Cool mode, fan to auto.
THEN TURN THE DEHUMIDISTAT TO 60,

I presume this is when the air is on., but it says DEHUMIDISTAT


So now I am really confused, is Munns wrong or what:cry:

Does it really matter what it is called?

As long as we know what it does. And in this case, let's just call it the 'device', turns on the AC unit when the humidity reaches a certain level.

Call it whatever you please I think we know what everyone is talking about.

Do you call the device in your garage a garage door opener or a garage door closer?

Do you call the pedal in your car an accelerator or a deaccelerator? (Okay, it's usually called the gas pedal, even on electric carts.)

Do you still "dial" the telephone?

Do you drink pop or soda?

Russ is absolutely right, does it really matter?

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.

Since it is wired in series, the AC would only run when the temp is above 78 and the humidity is above 60. This summer while I was up north, the electric bill was only around $60/mo.

EdV

Doesn't the AC come on if the temp or the humidity reach settings. If so why not set it at 90 instead of 78 as Munn's recommends?