Ecobee thermostats on hydronic system


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Old 01-29-17, 07:45 PM
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Ecobee thermostats on hydronic system

So I have a very similar setup with 5 zones and plan to put 3 new Ecobee thermostats in. I don't know where to connect the C-wire to either. I'm attaching a schematic of my setup - tried connecting to the C side of my 24V transformer - but the Ecobee kept restarting. They are telling me I need a transformer and relay per thermostat. Is that really true? Please help PJ!

Current Setup:
Name:  CURRENT.jpg
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I also was reading some other threads and think that if I just reverse the W and the Rh Wires at the thermostats then I can run the C wire to the currently installed Transformer (but I'm not an expert and need some help). I think that the reason that the Ecobee was restarting was something to do with phase with the current setup...

Proposed new diagram:
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Old 01-29-17, 08:06 PM
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Welcome to the forums.

I moved you to your own thread. The other one was too long and involved.

Yes..... your second picture will work.
However.... I would recommend an immediate transformer upgrade to a 24v 75va type.

amazon/product/B008HOVEGU/transformer
Honeywell also offers a similar model
 
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Old 01-29-17, 08:13 PM
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Cool. My only concern is that ecobee customer support is saying that I need to get isolation relays and a transformer for each of the thermostats, I don't need to do that right? I just don't want to ruin anything...

Also, The reason that the wiring is not ok in the first diagram is because the Rh needs to run straight to the R on the transformer I'm assuming, just confused as to why it functions without the C-wire as is?

Lastly, and thank you so much for the help ... the reason you're recommending I upgrade transformer is just based on the load that I have with 5 Zone valves and all the smart stats right?

Thanks again for everything. You're like a smart stat savior!
 
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Old 01-29-17, 08:24 PM
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Technically you don't need relays as the circuit will work fine. Ecobee may be recommending relays because they feel the load of the zone valve will exceed the handling capabilities of the Ecobee. I haven't seen any load problems yet.

There won't be any interaction between units as far as the wiring goes.

In your first diagram there was no need to keep the R and W correctly oriented as there were only two wires. With two wires there is no connection polarity. Now you need a third wire so the R and W orientation makes a difference.

Four zone valves is about the limit on a 40va transformer. So with five you're pushing it.
Now with the addition of the stats.... it will probably fail. I can say that the old transformers were of higher quality than todays and could run longer under a heavy load.
 
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Old 01-29-17, 08:37 PM
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Awesome. I had a feeling that was the case, but when talking to the support people about stuff I don't really have a good handle on, it's always hard to argue for what I'm hoping will work out. I'll order the beefier transformer today and report back on if it all worked out. Really do appreciate all your help for a total stranger. Thank you so so much.
 
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Old 01-29-17, 08:48 PM
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You're welcome and good luck.
Stop back after running the system to let us know how everything worked out.
 
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Old 02-02-17, 10:35 AM
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Thank you!!

PJ - Thanks so much for your quick responses and expert advice. I hooked everything up as planned out in my diagrams, and all seems to be working fine. Granted, I'm only 1 day into having them working, but as of now everything powered up and seems to be controlling each zone correctly. I really do appreciate your help, and hope this post finds other that need help with the same sort of setup!
 
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Old 02-02-17, 11:01 AM
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Awesome news and good job.
 
 

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