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Heat works fine but wont cool

aalonzo
Community Member

Hello, 

 

A couple of months ago I replaced my Honeywell with a Nest. I live in a condo, so at that time, only the heat was working. As winter is over, they recently changed the system to cool, I also changed the mode on my nest to cool, but I only feel the fan working.

 

See pictures of how was the Honeywell and how I wired the Nest.

 

Maybe the expert @Patrick_Caezza can help!

Thanks in advance!!!

 

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20 REPLIES 20

CoolingWizard
Platinum Product Expert
Platinum Product Expert

Your old thermostat has a W/Y and a Y/A terminal which I have never seen before.  So the question is, if the management company has to switch the water from hot to cold, what wire is the one that opens the water valve? Try switching her W1 and Y1 wires and see if that opens the water valve to your exchanger coil.

AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
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Patrick_Caezza
Platinum Product Expert
Platinum Product Expert

@aalonzo 

This is a new one for me.

It would help if you dig more into how your system was originally configured.

I learned that the Nest isn't the ideal thermostat for your application. It might work, but...

If the original Honeywell thermostat still has its configuration programmed and if you can access it. We can probably figure out how your apartment's HVAC is installed.

The two terminals we need to figure out are the W/Y and the Y/A terminals

TB8575 Digital Fan Coil Thermostats - Installation Instructions 

On page 6, Table 3 (Terminal Wiring. (Continued)) you;ll find what type of system you need to figure out that you have.

On page 9, Fig 18 or page 10, Fig19 are the two possible configurations that we need to figure out are installed at your apartment.

Page 11 has the installer setup (IS) mode instructions and you will need to use them to look at the IS Code 02 (System Type). We need to know which of hte seven opens is selected (Table 4, page 12)

NOTE

After writing all of that it dawned on me that all yuou might need to do is awap the ornage and yellow wires on the Nest base.

This is just a shot in the dark for a simple quick fix. I'm shooting from the hip on this one.

 

 


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aalonzo
Community Member

Thanks @Patrick_Caezza @CoolingWizard, it works!

First, I installed again the Honeywell just to make sure if it was actually the Nest and not the system. And indeed, with the old thermostat, everything is fine.

So I just switched W1 for Y1 wires as you suggested for the Nest and works!!! The only concern I now have is that when management changes again to heat, I think I will have to switch the wires as well.

Thanks for the help!

Patrick_Caezza
Platinum Product Expert
Platinum Product Expert

@aalonzo 

Yes, you will need to swap the orange and yellow wires back to their original location next winter when your heat is turned back on.

This is why I said the Nest thermostat isn't the ideal thermostat for this install.


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Jake
Community Specialist
Community Specialist

Hey aalonzo,

 

Thanks for the help Patrick_Caezza, and CoolingWizard.

 

I wanted to follow up and see if I could be of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further. 

Best regards,
Jake

Jenelyn_O
Community Specialist
Community Specialist

Hi there,

 

Chiming in — we hope you've got the answer you're looking for. Let us know if you have more questions in mind.

 

I appreciate your help, @CoolingWizard, @Patrick_Caezza, and Jake.

 

Thanks,

Jenelyn

Jenelyn_O
Community Specialist
Community Specialist

Hi aalonzo,

 

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know. 

 

Regards,

Jenelyn

CoolingWizard
Platinum Product Expert
Platinum Product Expert

@aalonzo,

The system you have confuses me.  If there is only a single water valve that opens a flow of water to your exchanger coil, and that valve is controlled by the Yellow wire, then yes, you will have to move the wire back and forth. Or, you can do something like a little MacGyver on it. 

AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
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CoolingWizard
Platinum Product Expert
Platinum Product Expert

Ok, here is the MacGyver approach.  Attach a jumper wire between the Y1 wire and the W1 wire. The nest backplate will not allow two wires in a hole.  Just strip back a little more insulation and then wrap a wire around the bare copper on W1 and connect the other end to Y1.  This will ensure which ever season the system is in, it will send power on the correct wire, the yellow wire.  Using this approach you will not have to switch the wires.  

AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
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@CoolingWizard 

Please don't make these types of recommendations.

It is not the wires that are the issue. It's the unknown function of the orange wire. The yellow wire appears to turn the heat/cooling on and off, so that wire was moved from the W1 terminal to the Y1 terminal since the apartment switched to cooling.

 

Your recommendation of connecting the orange (Y1) and yellow (W1) wires together might cause harm to the apartment system.


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@Patrick_Caezza , you are not following what he did.  He set it up and the thermostat so that wire would open the water valve to allow the hot water into the exchanger using the W terminal of the thermostat.  Then he followed my recommendation to swap the wires.  Therefore there is no danger to the system. Since you are not trained or licensed in HVAC/R industry, you are not qualified to make HVAC/R system recommendations. Heck, you probably have not even seen a Manual J.

This hydronic system uses a single water valve and a single water source.  Therefore the wire that controls the water valve is used for both heating season and cooling season.  Furthermore there is no danger to the Nest Thermostat nor the water valve if the owner implements the proposed modification. Most of the hydronic systems use a separate controller that the thermostat is connected to.  This allows the thermostat to signal a valve open and the controller to handle it. Why are systems built this was? It allows for the different water valves types independently of the thermostat to be used.  

Thank you for your concern @Patrick_Caezza , I have got this covered.  

The AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

@CoolingWizard 

You have come to this post a day after me.

You don't seem to understand, and you don't have it covered

You stated in your first post here that you were new to the Nest thermostat world on May 17th, 2022, and you had just heard about being a Nest Pro then. You even stated that you had just installed your very first Nest thermostat.

Now you claim to be a Nest Thermostat expert.

I've been a Nest Pro for a long time and have a better idea of what is going on than you do.

You know nothing about my experience and qualifications.

Get off your high horse and step back. You need to spend more time learning.


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Good Morning,

I would appreciate some help with the wiring.

I bought the new Google Nest Thermostat model G4CVZ.

My current Honeywell SuitePRO TB8575A1000 has R, W/Y, Y/A, Gi, Gm, Gh, C.

Any ideas on how to do the wiring? 


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Jake
Community Specialist
Community Specialist

Hey there,

I wanted to follow up and see if I could be of any help. Taking a closer look at the article here, I am showing you may have a fan with multiple speeds. If this is the case, I would recommend having a HVAC pro come out, and take a closer look at your system They would be able to review, and ensure everything is installed correctly. Please let me know if you have any questions from here, as I would be happy to take a closer look and assist you further.

Best regards,
Jake

Jake
Community Specialist
Community Specialist

Hey there,

I wanted to check in and see if you are still in need of any help. Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

Jake
Community Specialist
Community Specialist

Hey there,

I wanted to check in, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake

aalonzo
Community Member

Update:

 

It is not compatible, had to buy a Nest Learning Thermostat, wich is compatible.

Markjosephp
Community Specialist
Community Specialist

Hi aalonzo,

 

I've duplicated your thread in the main one here. You’ll receive all updates on this issue on the main thread, and we recommend updating and checking this thread when needed.

 

Regards,

Mark

CoolingWizard
Platinum Product Expert
Platinum Product Expert

@aalonzo , you can use the Nest thermostat you have purchased but you will probably want to pick the fan speed you want to use.  The primary fan speed would go on the G terminal.  Your speeds are Low, Medium, and High. Low is blue wire, Medium is red wire, and High is brown wire.  You choose the desired speed and put it in G.  The water valve controller is controlled by the Yellow wire.  For cooling place the yellow wire in Y.  For Heating season, the yellow wire needs to be moved to W. The orange wire in Y/A should be taped off and in used. This is the Auxiliary valve control.  This is present when the exchanger coil has a second circuit to increase the BTU performance of the coil.  When there is dual circuit water supply the Y/A would be wired to the Cold Water supply.   We do not know about your system but statements made advised me that the building management does the water changeover between summer and winter.  This implies a single water valve and an axillary circuit. You can think of this as second stage heating or second stage cooling. Your Nest thermostat you purchased cannot support 2 stages of heating or cooling. 
So, the power is the on the black wire currently attached to R. The power common is the white wire on C. Those two are straight forward. The fan is the wire on Gl, Gm, Gh.  Typically if you live in an area with high humidity, you would cool with Medium to allow the air to be in contact with the coil longer and thus remove more moisture.  If you are in the dryer parts if the country you would cool on High and Heat on Medium.  Choose the speed and for now place it in the Nest G terminal.  Place the Yellow wire in Y for cooling season, and in W for heating season.  

Feel free to ask any additional questions for clarification. 

AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.


@Patrick_Caezza wrote:

@CoolingWizard 

You have come to this post a day after me.

 >> go to top post, I posted the same as you and before you. 

You don't seem to understand, and you don't have it covered

>> What is it you claim I do not understand? 

You stated in your first post here that you were new to the Nest thermostat world on May 17th, 2022, and you had just heard about being a Nest Pro then. You even stated that you had just installed your very first Nest thermostat.

>> Yes you are correct, I made post here as you stated. However, I have been installing Nest Thermostats since 2008; 168 installed to date. I installed my first as a registered Nest Pro in May. 

Now you claim to be a Nest Thermostat expert.

>> I have installed, debugged, problem analyzed, and repaired many Nest products over the years.  

I've been a Nest Pro for a long time and have a better idea of what is going on than you do.

>> sure you have, but you are ignorant on the operation and science of refrigeration technology. You knowledge level is how to connect a nest thermostat to multiple connectors.  You know what each wire is supposed to do.  You are ignorant on the technology of Refrigeration itself. 

You know nothing about my experience and qualifications.

>> You are correct I do not know your experience or education. I have shared my experience and Education. The question is why have you not shared yours? You cannot claim to be an expert just because you can type.  

Get off your high horse and step back. You need to spend more time learning.

>> I do not have a horse of any types. I still walk on land.  

AC Cooling Wizard


 

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.