Dehum thermostat capability?


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Old 02-14-19, 08:20 PM
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Dehum thermostat capability?

I have a Rheem system that isn't terribly old, but I do not know a lot about it. You guys helped me set up a DEHUM t-stat with a Carrier unit I owned, and I can once again use your help!

Rheem 4 Ton:

RPQL-048JEZ. Compressor
RHLL-HM4821JA. Air handler


It is a heat pump system and it currently has a Honeywell ProSeries stat.

What I want to know about this system is that is seems to be a high efficiency system ,but it is not a VS blower or multi stage system, correct?

Also, I want to add a wifi capable thermostat WITH the ability to control humidity, but I do not know if this is possible. Does this system have the capability? Compressor documentation says it can when it's matched with a High Efficiency ECM Handler. If this unit CAN handle humidity control, what thermostat can I purchase to do it and how does it connect? I have done this with other units, but I am not familiar with this one.

I did do some research before coming here but I came across a few manuals and didn't really figure a lot out. Thanks a BUNCH!
 
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Old 02-15-19, 02:47 AM
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A central air conditioner systems primary job is NOT removing humidity. It does so as a by product of its operation.
Your air handler has a multi tap motor which may provide you the control you're looking for. Most techs would set the fan one step below the highest setting. This should provide adequate airflow and humidity control. Slowing the fan down would allow for more humidity removal. But may make the home uncomfortable. Personally I opt for the stand alone dehumidifier and use it when I need to. Where ever you set the sensor is where the unit will use for its set point. If the sensor is in the wrong place then your home will be uncomfortable. If this is a recent install ask for the Manual J and D calculations. J is for load D is for the duct work. Your duct work MAY influence your ac more than you know.
 
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Old 02-15-19, 03:15 PM
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Yes, I am aware of how to make all of these calculation including the heat load calculation. I am aware of how the AC works and how it dehumidifies. However, my fancy AC utilizes humidity control through the thermostat. It can either slow down the blower OR it can over cool to get the job done. As you know, AC sizing is for hitting the 'average' for most conditions depending on your location and home. Sometimes, it it handy to have the ability to dehumidify a section of the house. I was just trying to find out how to utilize a wifi thermostat with humidity control capability on the system in the original post. Since it is a single speed system, the only way of handling the occasional high humidity situation is by over cooling, as far as I know.
 
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Old 02-15-19, 05:18 PM
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https://resource.gemaire.com/is/cont...wd.pdf?fmt=pdf

It looks like that air handler has an ECM X13 motor. It doesn't have a terminal to connect to a thermostat dehumidify terminal.

A Honeywell TH8321R thermostat can overcool to dehumidify.
It could also connect to a duct mounted Aprilaire 1850 dehumidifier.

The R in the middle of that model number is for redlink. I can check on the wifi model. TH8321WF.
 
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Old 02-15-19, 05:31 PM
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http://www.sedefficiency.com/docs/Ho...Pro-Manual.pdf

Yes the Honeywell TH8321WIFI can overcool to dehumidify or it would allow you to change this to control a separate dehumidifier if you should decide to upgrade.
 
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Old 02-16-19, 10:07 AM
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Hey Houston204! You helped me with my Carrier!

I think that thermostat is the one you suggested for it as well. Thanks for the info!

By the way, will this thermostat work as well?

RTH9585WF1004
 
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Old 02-16-19, 04:56 PM
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https://www.honeywellstore.com/store...tat-manual.pdf

The R in front of the model number indicates that it is the stripped down model sold in big box stores. It does not have the dry contact "U" terminals and I see no mention of overcool to dehumidify in the manual.
 
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Old 02-16-19, 09:23 PM
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Yep...your right. I looked around a bit more and there are actually very few that do anything with humidity. The one you mentioned in the first post does and it looks like the TH9321 will as well. Its a touch screen and color. Both will use multiple indoor sensors and my wireless outdoor sensors.
 
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Old 02-18-19, 08:02 AM
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dehumidification of a room

That is next to impossible to accomplish with a central system. You can lower the whole house, not just a room.
I understand what you want to do, the only thing I can think of is to slow the air handler down one speed. Less air volume may result in more dehumidification. The location of your stat will be the set point for the unit.
 
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Old 02-20-19, 01:21 AM
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I like the Honeywell Prestige IAQ. It will support a wireless outdoor temperature and humidity sensor plus multiple indoor sensors but the averaging is only for temperature. The humidity is read from a single indoor sensor .
 
 

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