Trane T900 THERMOSTAT

[bluffdad]

Does anyone know if the T900 stat will control the variable speed fan in a 4TEE3FB40 air handler with the XR15 condenser? I'm looking for a dehumidify on demand feature. The system is going to be installed in a few weeks and the installer said we could use the existing stat, but I found a good deal on the T900.

[grofva62]

The TAYSTAT900 control is only good for communicating equipment and the XR15 is a non-communicating unit and the variable-speed air-handler would have to be a "C" model to work with that stat. It would need to be a 4TEE3CXXA model. The XX could be from an 01 - 10 in the model number depending on which outdoor unit.

[RyanHughes]

The air handler needs to be the communicating model. 4TEE3C05A1 or whatever the rated match with your tonnage is.

Or you could use the Honeywell VisionPRO IAQ and receive similar results.

[grofva62]

If I'm not mistaken, the dehumidification feature on the 900 & 803 stats is NOT going to give you dehumidification on demand. It's only going to give you extra dehumidification to the point where the system will overshoot the cooling setpoint up to a few degrees to reach your desired humidity level. You will probably need an additional humidistat and electric heat for "re-heat" to have some level of dehumidification on demand. The other option would be to install a "whole-house dehumidifier" such as the ones that Honeywell & Aprilaire as well as some others make.

[RyanHughes]

If I'm not mistaken, the dehumidification feature on the 900 & 803 stats is NOT going to give you dehumidification on demand. It's only going to give you extra dehumidification to the point where the system will overshoot the cooling setpoint up to a few degrees to reach your desired humidity level. You will probably need an additional humidistat and electric heat for "re-heat" to have some level of dehumidification on demand. The other option would be to install a "whole-house dehumidifier" such as the ones that Honeywell & Aprilaire as well as some others make.

On the 803, yes, it just overcools by a few degrees to dehumidify.

The advantage with the 900 thermostat is that it can control control the blower speed for dehumidification. You choose a percentage of airflow for dehumidification, for example 80% of cooling CFM.

Ryan

[grofva62]

That is true but it's still not going to be dehumidify-on-demand if the setpoint is satisfied and humidity level is rising. I have a wiring diagram to solve this issue using re-heat but it's on a different computer. The humidistat & 5kw heater only adds a little more to the price of an install. Of course operating costs increase but true dehumidification is accomplished. It all depends on what Bluffdad is trying to do.

[RyanHughes]

I was not aware of that, thanks for that info. I know the Honeywell IAQ version of that t-stat can do dehumidification on demand, if that's what the OP is most interested in.

[Airmechanical]

That is true but it's still not going to be dehumidify-on-demand if the setpoint is satisfied and humidity level is rising. I have a wiring diagram to solve this issue using re-heat but it's on a different computer. The humidistat & 5kw heater only adds a little more to the price of an install. Of course operating costs increase but true dehumidification is accomplished. It all depends on what Bluffdad is trying to do.

your wrong, the dehumidification program on the XL900 stat can overcool by 3 degrees or less if you prefer

also, your costing 20 amps everytime the element on your reheat wiring diagram comes on, it's much too costly to operate

if your needing to reheat to dehumidify, you have insulation/leak problems

fix the leaks and insulate or install a whole house dehumidifier

or you could look into heat pipe application, which is RARELY discussed here

here is a link Heat Pipe Technology

http://www.heatpipe.com/





.

[bluffdad]

I was under the impression this stat was a re-branded Honeywell IAQ and that it could control a variable speed blower to help with dehumidifying. Everyone is in agreement it will not? I'm a bit confused with all the answers.

[RyanHughes]

It will control blower speed to dehumidify. The IAQ can dehumidify whether or not their is a call for air conditioning--whether or not the TCONT900 can remains to be seen at this point. I thought it could, but another member is saying otherwise. Anyone able to clarify this? To answer your question, yes, it can control the variable speed blower. But whether it will do this when there is NOT a call for cooling, I don't know.

[Airmechanical]

It will control blower speed to dehumidify. The IAQ can dehumidify whether or not their is a call for air conditioning--whether or not the TCONT900 can remains to be seen at this point. I thought it could, but another member is saying otherwise. Anyone able to clarify this? To answer your question, yes, it can control the variable speed blower. But whether it will do this when there is NOT a call for cooling, I don't know.


if your not sure about what you have been told

read the manual

it's very straight foward


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[Airmechanical]

I was under the impression this stat was a re-branded Honeywell IAQ

wrong



.

[RyanHughes]

if your not sure about what you have been told

read the manual

it's very straight foward


.

Integrated Temperature and Humidity Control
(ITHC)
The dehumidification control attempts to control the
indoor humidity to the user’s dehumidification setpoint by
running the compressor. The dehumidification setpoint
can be accessed by pressing the More key until the
dehumidification setpoint is displayed on the screen. The
setpoint can range between 40% and 80% in 5%
increments. When enabled, the default dehumidification
setpoint is 50%. In extremely high humidity conditions, the
Comfort Control keeps the compressor running for up to
3°F (-1.7°C) below the temperature setpoint. It does this
while trying to achieve the desired dehumidification
setpoint and balancing that with the temperature setpoint.
The maximum allowable dehumidification

[bluffdad]

Integrated Temperature and Humidity Control
(ITHC)
The dehumidification control attempts to control the
indoor humidity to the user’s dehumidification setpoint by
running the compressor. The dehumidification setpoint
can be accessed by pressing the More key until the
dehumidification setpoint is displayed on the screen. The
setpoint can range between 40% and 80% in 5%
increments. When enabled, the default dehumidification
setpoint is 50%. In extremely high humidity conditions, the
Comfort Control keeps the compressor running for up to
3°F (-1.7°C) below the temperature setpoint. It does this
while trying to achieve the desired dehumidification
setpoint and balancing that with the temperature setpoint.
The maximum allowable dehumidification

Thanks for the research. The stat is in the mail and I don't yet have user's manual.

[grofva62]

your wrong, the dehumidification program on the XL900 stat can overcool by 3 degrees or less if you prefer

also, your costing 20 amps everytime the element on your reheat wiring diagram comes on, it's much too costly to operate

if your needing to reheat to dehumidify, you have insulation/leak problems

fix the leaks and insulate or install a whole house dehumidifier

or you could look into heat pipe application, which is RARELY discussed here

here is a link Heat Pipe Technology

http://www.heatpipe.com/





.

I should have said if the t-stat is satisfied within 3 degress of setpoint. As for the reheat, I never said it would be cheap to run but it will work. Just as buying and installing the heatpipe coil will not be cheap either plus it could void his factory warranty. Buying a wholehouse dehumidifier won't be cheap either but their all viable options for dehumidification. You could be correct on fixing the leaks if that is the source of his humidity problem. If he has a home gym or something like an indoor raquetball court, then leaks ain't the problem.

[Byrdalak]

communicating equipment

Just what does this mean? The T-stat uses information from the air handler? This is new to me. Thanx.

[RyanHughes]

Just what does this mean? The T-stat uses information from the air handler? This is new to me. Thanx.

Quicker setup because the components self-recognize. Diagnostics. Increased features such as dehumidification already built into the system and control. 3 wire connection. The 20i from Trane has ChargeAssist which has an indicator for when the unit is charged properly. There are some other benefits too. I would look at info on Trane's ComfortLink II system, communicating XL16i/20i/4TEE air handler, and XL900 thermostat. Carrier also has a very nice communicating system called Infinity. And other brands are developing similar products as well.

[grofva62]

Amana actually just came out with their ComfortNet system on their 16 & 18 SEER outdoor units. It's pretty slick. There is no contactor in the outdoor unit and it's been replaced by a sealed contact on the board so there is no arcing or chance of corrosion. It also stores the program for the variable-speed fan motor on the board of the indoor unit so just put a blank drive on the end of the motor if the drive fails and it programs itself. You can check the model & serial numbers of both units at the t-stat. They are supposedly testing it right now for remote internet programming which you can't do with the Trane system which uses acient telephone access with the phone voice menu from hell.

[Airmechanical]

Thanks for the research. The stat is in the mail and I don't yet have user's manual.

http://www.bayareaservice.com/Manuals/tcont900.pdf



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[Airmechanical]

II never said it would be cheap to run but it will work. Just as buying and installing the heatpipe coil will not be cheap

ya but the heat pipe cost O to operate

please post a link where you read that the Heat pipes void the factory warranty

or did you think that up, all by yourself



.

[Byrdalak]

Thanks guys, it's stuff like that I need to brush up on.