Install Ecobee3 Lite - No Existing Thermostat

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Old 09-01-20, 10:00 AM
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Install Ecobee3 Lite - No Existing Thermostat

I live in a high rise building constructed in the 1960s. The building has a pipe system, where there is a boiler and a chiller in the basement, and the building turns over from heat to cool based on the season. I have no control over heat or cold, only the fan in my condo which blows air over the heated/chilled pipe. All I have to control the unit is a three position switch for high speed / off / low speed. I'm trying to connect an Ecobee3 Lite to automate the process of turning the blower on and off based on the temperature in the room. I fully expect to lose the ability to choose high and low speed, and that's fine. I'm perfectly happy running the blower at high speed only.

I'm doing a full renovation, and I had my contractor run a 5-wire thermostat cable from the HVAC, under the floor, and through the wall in advance of getting to this point. Unfortunately, neither my GC, nor his electrical subcontractor know how to make this system work.

I've tried to use this post as a guide, as my building operates similarly, but to no avail. https://www.doityourself.com/forum/t...il-system.html The fan controls in the post are a bit different than mine, and I can't quite figure out how to get from the other user's setup to my own.

I've also reached out to my building engineer, who suggested a Honeywell fan center https://www.supplyhouse.com/Honeywel...ncludes-R8222B, but when he tried to install it, the blower turned on right away, without even putting the Ecobee head unit in place. He then tried a different configuration, and the Honeywell just buzzed like it was going to explode when we turned the power on. I think this might be an appropriate solution, route, but I would need to try the installation myself given the previous experience with the building engineer. The manual is a bit overwhelming though: https://s3.amazonaws.com/s3.supplyho..._PROD_FILE.pdf

Alternatively, I purchased a 24V Transformer: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 to power the Ecobee, but it's not recognizing the switch.

So basically, I have a lot of options, but I'm a little short of knowledge. I feel like I'm close though...


Here's what I'm working with:


In the picture showing the wiring into the switch, there are two batches of wiring. The near batch has only two wires - red and white. Both are heavy gauge solid copper. The far batch has three wires - red, white, and blue, all braided copper. There are a lot more wires connecting to the motor, but I can't tell what anything else is connected to. I'm not entirely sure those other wires matter, so I'll leave those out of the equation for now.

So all that said, here's an explanation of connections I can see:

Near red (solid copper) to center position of the switch
Near white (solid copper) to far white (braided)
High speed terminal to braided red in far batch
Low speed terminal to braided blue in far batch


Any thoughts on how to wire all this up through the Ecobee would be much appreciated.

Thank you in advance!



Note the "near" wiring on the left and the "far" on the right. The "near" batch is solid copper, the "far" is braided.

 
  #2  
Old 09-01-20, 01:44 PM
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First verify the "near" is the supply, is 120v, and is truly dead when you turn off the breaker. Get a multi-meter.
If you wired the switch directly to the Ecobe you likely fried it as it is only rated for 24vac.

Fan center power (black and white) would attach to near red and white (keep connected to far white).
Fan center's black/comm would attach to the near red along with the black power.
Fan center's red would attach to far red or black depending on which speed.
Ecobee then can attach to R, C, and G
 
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Old 09-01-20, 02:35 PM
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Thanks for the response! First - yes - the near is the supply - 120v and terminates at the breaker.

As for the meat of your direction, I'm a bit confused. What specifically are you referring to with respect to "fan center"? The "far" wires are all attached to the blower motor, so attaching the "fan center's red to far red" isn't possible. The fan center red IS the far red, as I'm understanding it.

Also, could you help me understand how this would be a wiring design that wouldn't fry the Ecobee? I don't see any kind of transformer to reduce the voltage from 120v to 24v, so wouldn't this entire circuit be 120v?

I went a little farther down the rabbit hole and pulled the housing off. The red, white, and blue wires from the "far" section are all connected directly to the motor. The motor has three wires that aren't connected to anything - black, yellow, and orange. My understanding is that the motor has more than 2 speeds, and these extra wires are for those speeds. I'll try to confirm with the building engineer.
 

Last edited by Rob Pellegrini; 09-01-20 at 02:50 PM.
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Old 09-01-20, 06:03 PM
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The fan center (also called a fan control center) is what your building engineer tried to install. You included a link. A fan center has both a 24vac transformer (to power the thermostat) and a relay (to use the 24vac coming from the thermostat to switch the 120v going to the motor).
 
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Old 09-01-20, 10:37 PM
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Welcome to the forums.

To build on Astuff's help.......

Using the fan center you linked to. There are five wires coming out of it.

Black – common
Red – N.O. contact
Brown – N.C. contact - CAP OFF - not needed

Black - 120v
White - neutral

The two black wires connect together and get connected to 120vAC hot which is the red in the pic.
The white wire connects to the white neutral wire in the picture. Three white wires total.
The red wire connects to black switch wire which goes to center of switch.
The switch will still work to select speeds.


On the front of the fan center...... you'll be using R, C and G. I just picked typical colors. Use three wires from your five wire cable. At the Ecobee you'll be using Rh, C and G. In A/C mode.... the thermostat automatically controls the blower. In the heat mode..... you'll have to program the thermostat to control the blower.



I've never used an Ecobee to only control a blower. The thermostat may say it's missing the Y line in cooling and the W line in heating. Let us know if that happens.
 
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Old 09-02-20, 09:38 AM
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Thanks for the insights.

Astuff - sorry for the confusion - I forgot the Honeywell part was called a fan center. Also, I don't have one right now - the building engineer took it with him. Out of sight out of mind.

I just ordered it on Amazon and will update in a couple days. Fingers crossed!
 
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Old 09-03-20, 10:07 PM
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Ask before connecting if you have questions.
 
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Old 09-05-20, 01:24 PM
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IT WORKS!!!!!!!!!!!!

Not exactly as you had drawn it up, but yes, it is indeed working. I wired up as the fan center as Astuff suggested - taking the switch out of the system. I don't want the switch, and I prefer systems with as few variables as possible.

Here's where I had to ad-lib a bit. When I connected Rc, G, and C to the Ecobee, the Ecobee only gave me options to turn the fan on and off. Basically, I just swapped out the physical switch for a fancy touch-screen switch. I shut the system down and added the W1 and Y1 connectors, having read from other research that these are heat and A/C controls respectively. I also know that the Ecobee automatically jumpers the Rh if only an Rc is connected.

When I reattached the faceplate, I then had options for "Heat" and "Cool". Now obviously, given the type of setup in my building, I can't create heating or cooling on a whim - it depends on the season and the temperature of the water running through the pipes. But, I was able to test the concept. At the time of installation, the temperature of the room was 74. The building is currently in cool mode, and when I set the thermostat to 68 - the blower cycled. I then changed it to "heat" mode, and the blower turned off. Keeping the Ecobee in "heat" mode, I set the desired temperature to 78, and it again cycled. So basically, I will manually change "heat" and "cool" mode when the building turns the pipes, and the Ecobee will do the rest.

Thank you SO much for the help. This is the first time I've had a thermostat since 2013. Truly, it's a life-changer.
 
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Old 09-05-20, 07:03 PM
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Good to hear that you got it working and figured out a trick. Sometimes the smart thermostats are too smart.
 
 

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