Ecobee thermostat issues.

[lateapex911]

Seems I'm away from home a LOT these days, but in unpredictable ways. Last week I spent maybe 30 hours in my house. So, with oil costing a fortune, it's seems prudent to turn the heat way down. But, I have hydronic heat, and when I get home, it takes hours to get back up to decent temps. Just in time to leave again.

So, I got an Ecobee thermostat. It's linked to my network via wifi, and I can control it anywhere via the internet on my iPhone. Which is pretty cool, because the new iPhone software has a gps based reminder, and I've set a reminder that triggers when I leave the house to set the heat back. I've also set one that triggers when I leave the work site to turn it up. So I just open the ecobee app, and turn up the heat. A second later, things are warming up. If I KNOW when I'm leaving work, I could turn it up hours ahead, and it would be warm when I get home.
OK, thats the background.
Here's my issue.
My furnace is a classic hot water with an Honeywell Aquastat that fires the burner and runs the circulator pump (until the water hits the high limit setting) when the thermostat closes the two "T" contacts on the aquastat board. IT's a 24V AC transformer that then closes a relay.
Suuuper simple, two wires.
But the Ecobee wants THREE wires, and needs a 24V ACsupply. I have three wires, but I'm really feeling stupid as I don't know what to connect the third wire to down on my furnace.
I know most of you guys are brighter than me, can anyone point me in a direction?
Ecobees support people told me it only works with a 3 wire common system. (I was calling from the job and the inspector chose that moment to show up for the final, so thats all I got from them.
(Passed the final in under a minut, phew, LOL)

Heres a link to my Aquastat
https://customer.honeywell.com/resources/techlit/TechLitDocuments/95-0000s/95-6940.pdf

and the Ecobee manualWiring diagram on page 15)
http://www.smarthome.com/manuals/29919-ins.pdf

Thanks in advance!

 

[ishiboo]

It sounds to me with hydronic, the Ecobee expects to control the burner and circulator pump separately... as it would the burner and the fan on forced air. I would call Ecobee and verify though.

If they won't help you, buy a Nest

 

[philjafo]

Your tstat is looking for what would be labeled R W C on a forced air system. If you have a multimeter check your 24 volt transformer one lead to ground and the other to the transformer should read 24 volts that would be R. The other terminal should read 0 volts and would be C. Do the same check where the wires for the old tstat hooked up one will read 24 volts that's R the other will read 0 volts (disconnect the old tstat wires first) that one is W.

Now run your new 3 wire from the new stat to the boiler connect R and W to the same place as the old tstat and connect C to the transformer.

 

[lateapex911]

Ah, now we are getting somewhere. Great stuff, thanks so much, I will get my fluke multimeter, and I will get on it and post my results.

 

[where2]

I love my Nest, but the Ecobee did seem like a great alternative. I'll have to tinker with those GPS based reminders on my iPhone. I keep forgetting those are there.

 

[lateapex911]

Your tstat is looking for what would be labeled R W C on a forced air system. If you have a multimeter check your 24 volt transformer one lead to ground and the other to the transformer should read 24 volts that would be R. The other terminal should read 0 volts and would be C. Do the same check where the wires for the old tstat hooked up one will read 24 volts that's R the other will read 0 volts (disconnect the old tstat wires first) that one is W.

Now run your new 3 wire from the new stat to the boiler connect R and W to the same place as the old tstat and connect C to the transformer.

Thanks! Ok, I checked the T terminals, and one read 9VAC, and the other 4VAC. My Fluke digital VOM was set to AC, and I used the chassis as ground.

I'm a bit confused with your directions. The R stat terminal goes to the 24V T terminal on the aquastat. The W from the stat goes to the other T terminal with zero volts. The C stat connection though, you say goes to the transformer....where on the transformer? On my aquastat, the only connection I can access are the T terminals. I'm missing something...and feeling stupid! LOL.
Here's a link to the Aquastat, showing a picture of it.

https://customer.honeywell.com/resources/TechLit/TechLitImages/Large/L8148A-c7.jpg

 

[philjafo]

Ok the picture helps, I thought your aquastat was different with a seprate transformer. It looks like your going to need a fan center relay, having trouble loading images now but google has lots of images of them and I'll try to put one up later.

 

[lateapex911]

Ok the picture helps, I thought your aquastat was different with a seprate transformer. It looks like your going to need a fan center relay, having trouble loading images now but google has lots of images of them and I'll try to put one up later.

Thanks.
yea, the transformer is on the board. I got to the back of it, and all the readings were the same essentially. Tried a dozen different locations such as the neutral wire.

In the end, I added a separate power supply and it's operating normally now, EXCEPT, it's in the cellar.
Turns out the wire has a break in it somewhere in the wall, and only two conducters have continuity. There was a section spliced in down near the boiler that was bad too, but I replaced that.

So, a wonky transformer, and TWO bad wires. Not an easy troubleshoot!
Now I have to get a wire up two stories, and THEN I'll be done with this "!5 minute installation" LOL
Thanks for all the help and suggestions.

BTW, this unit is ideal for a remote garage that isn't on a set schedule. It has a fast response time. When I set it up for communication testing, I watched the time it took from when I changed the setting on my iPhone app to when the stat changed the setting, and it was maybe 2 seconds. Way cool.