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Installing Ecobee with 2 wire boiler system in basement air handler in attic

Installing Ecobee with 2 wire boiler system in basement air handler in attic


  #1  
Old 05-22-17, 07:59 AM
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Installing Ecobee with 2 wire boiler system in basement air handler in attic

Lots of frustration this weekend!

I have a Taco ZVC403 in the basement, so T T set up and no common.

My old T-stat used Rh and W from boiler side and Rc G Y from air handler.

Once I found out I needed a common wire for the Ecobee, I bought a fast stat common maker. I tapped into the common coming from the low voltage side of the transformer and wired the fast stat as suggested for the rest. The ecobee did power up! When I added all the wires from the air handler from old T-stat (Y G Rc) there was a wiring error on Ecobee. So I took those out and had C Rh and W from boiler (fast stat sender unit). Everything looked OK until I called on the heat. There was an awful clicking/buzzing noise coming from the fast stat unit next to the boiler control panel and the heat never kicked on.

I undid everything and re-installed my old thermostat.

What did I do wrong and what can I do to get everything to work?

I've read about fishing new thermostat wire to the boiler. I'm willing to do that but don't know what connections I would need to make.

There are unused wires in the wire between the boiler and thermostat. Can those be used?

I have not seen the panel on the air handler as it is in a very hard to access area in the attic.

Any advice is much appreciated.
 
  #2  
Old 05-22-17, 09:24 AM
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If there are spare wires at the stat from the boiler then there is no need for the common maker. What are the colors of the spare wires?
 
  #3  
Old 05-22-17, 10:27 AM
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Welcome to the forums.

The Common MUST come from the ZVC403. The C is common with your stats. Your stats are connected to T T.

I can help you get a C connection from the 403 plus identify the T T terminals as R and W. You need to post a well lit picture of the 403. You will also need a voltmeter to check for 24vac.

http://www.doityourself.com/forum/el...-pictures.html
 
  #4  
Old 05-22-17, 12:19 PM
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OK, here is the control panel. I have a multimeter and think I have identified the common but would love your input.

What I did was measure from either the red or yellow on the far left to the red or white at thermostat 2 which is the boiler.

Once the C is identified, is it just a straight single wire connection from there to C on the tstat?

For the reply about what colors are spare, there is a brown, yellow and blue.

Does anyone have any ideas why there was a wiring error on the ecobee when the air handler wires (Rc Y G) were attached but not when I removed them?

The guy I was talking to at Ecobee support suggested my solution would be to use the air handler G as C and jumper Y and G. I feel like this is an unnecessary step in the wrong direction as I would lose manual control of my fan.

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Last edited by Chemguy0910; 05-22-17 at 01:25 PM.
  #5  
Old 05-23-17, 05:43 PM
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Labeling Taco zone control panel.

Remove the red and white wires from the T T terminals on the zone you are using.
Install a short across the T T terminals.
Put one lead of your meter on the T T terminal shorting wire.
Touch the other lead to where the transformer connects. The terminal that shows 24vac is C.
Label that transformer terminal as C.
Remove the T T jumper.
Put one meter lead on the transformer C terminal.
Touch one T terminal and then the other. The T terminal that shows 24vac gets labeled R.
The other terminal is W.
Know you know your R, W and C connections at your heating end are correct.
 
  #6  
Old 05-23-17, 09:16 PM
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Ecobee's installation manual shows using C from the air handler, not from the boiler.

From page 31 - https://www.ecobee.com/wp-content/up...ationGuide.pdf

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  #7  
Old 05-23-17, 09:49 PM
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In reading thru the manual I get the impression that the C can come from either transformer but in most cases it needs to come from the cooling system. That could be the case here.

You can use the supplied PEK to get C from your air handler.
 
  #8  
Old 05-24-17, 04:40 PM
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None of the smart thermostats seem to have very good documentation for dealing with complex systems. Did some searching and found this from https://support.ecobee.com/hc/en-us/...ouble-shooting - Name:  1or2 transformer.png
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Also found a reference with the Si model saying just the opposite. Argh!! Then found note on how the PEK is wired differently to the new 3 lite and 4. Apparently there is a dedicated PEK terminal at the stat for "Y" wire to connect to as well as "G" goes to the C terminal. Guaranteed to drive cause problems.
 
  #9  
Old 05-24-17, 05:24 PM
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Here's some more confusion.

  • Note 1: with a 2 transformer configuration RC & C must be connected to the same transformer.
  • Note 2: with a 2 transformer configuration PEK module cannot be used.

That would mean the PEK couldn't be used here.
 
 

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