Add thermostat to my IEC FXY fan coil unit ?


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Old 07-08-22, 01:31 PM
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Add thermostat to my IEC FXY fan coil unit ?

Hi Atropin,

I think I have a similar setup and wondering if this is easy enough to set up for someone without prior experience wiring thermostats. Also, did you get the Amazon smart thermostat with a C-wire adapter?



Separated from: How can I add thermostat to my IEC FXY fan coil unit?

 

Last edited by PJmax; 07-08-22 at 03:33 PM.
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Old 07-08-22, 03:42 PM
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Welcome to the forums.

Sorry.... too many posters in the same thread. I should have closed it sooner. If you'd like to communicate with Atropin.... go to that thread, put your cursor on the name and select private message.

You have a fan coil that uses 120v switching.
If you want just basic one function switching..... like fan on and off.... you can use a fan center to give you 24v for the thermostat and a relay to control the 120v fan. Based on the model of thermostat you want to use there are several light duty solutions to the problem.
 
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Old 07-08-22, 08:25 PM
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No worries. Thank you for moving. Am completely unfamiliar with this area and on/off is just fine for me as I'm just trying to regulate temp in my toddler's room without going in during the middle of the night and risk waking her up.

By fan center, do you mean the relays mentioned in the other thread? I just put an order down for the Aube Technologies RC840T-120 relay that folks were mentioning. Is that what you were referring to? I was mostly just trying to hook up the least expensive thing so that I could control the temp from my smartphone. Don't need any special programming. I'll probably even tuck the thermostat away inside the wall unit if I could.

I figured I'd pair it with the Amazon Smart Thermostat as the other thread mentioned because prime day has a good deal on it, but I don't know whether I need the C wire adapter or not. What do you think? If you have other options to recommend that'd be great also. Thanks!
 
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Old 07-09-22, 09:35 AM
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The Aube relay is a limited output 24v device. It will run electronic thermostats with no problem. It does not run all smart thermostats that are wifi capable. You won't know until you try it.
 
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Old 07-09-22, 04:54 PM
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Thanks Pete. Will try to order the one without the c wire adapter and see if it works. Question with the actual wiring. I apologize in advance if this sounds stupid, but trying to make sure I have the wiring correct for the relay.

So from my image it looks like red/blue/black control the fan speed so I'll probably just leave that in one spot. Looking at the diagram, right now yellow is hooked up to L1. I'm guessing based on the relay product I disconnect those two and connect L1 to the black wire on the relay and yellow from the switch to red on the relay. For the white wire coming from the relay I have to find where the white wire from the motor connects to L2 and just join that connection.

The C/W/R side is just the thermostat side which should be straightforward (hopefully).

Does that sound correct? And I'm guessing the order I connect wont matter since I will have the power to that area shut off.
 
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Old 07-09-22, 06:01 PM
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You don't need a C wire adapter. The Aube supplies the C.
As mentioned it will run all smart stats and most wifi capable thermostats.

Since you'll be using the Aube for cooling and heating.... you'll connect the W wire to G. G is the fan and can be activated in heating and cooling mode. So in heating mode if it mentions electric heat.... choose that.
You can let me know the exact stat you're using.

With this setup.... the stat turns the fan on or off. The speed control still works to select speed.
 
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Old 07-12-22, 06:12 AM
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Hydrotherm Boiler won't light Pete,

Thanks for the diagram! Super clear what I need to do. I ended up getting the Amazon Smart Thermostat. I'm guessing 18/5 thermostat wire should be enough. Are the three wires you mentioned all that I need to hook up to this?

The back looks like this:
 

Last edited by PJmax; 07-12-22 at 11:38 AM. Reason: labeled pic
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Old 07-12-22, 11:40 AM
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Yes...... three wire connection.
In setup set it for electric furnace.

The G (fan) terminal will activate in heating and cooling.
 
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Old 07-13-22, 07:50 AM
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Thank you so much Pete for being patient. Stat turns on and can control the fan. Just working through some issues with the Alexa app now where it can see the settings on the stat but doesn't seem to be able to change it.
 
 

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