topic Re: E19 wiring report Y2 wire without Y1 wire in Nest Thermostats

E19 wiring report Y2 wire without Y1 wire

MikePage — Thu, 04 May 2023 14:12:34 GMT

This is a new Google Nest Learning thermostat I am installing to replace an old thermostat. There are only two wires going to the thermostat from the boiler: R and W. The Nest is supposed to be compatible with this wiring. So, the error makes little sense to me. I also charged the Nest with a USB cable overnight, so should be fully charged.

Below are photos showing the error and wiring. Any assistance in resolving this would be welcome. Thanks.

Error messageWiring

Re: E19 wiring report Y2 wire without Y1 wire

CoolingWizard — Thu, 04 May 2023 15:51:37 GMT

Can you do us a favor and take the display off, and take a picture of the back plate with the wires attached?

AC Cooling Wizard

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 16:10:22 GMT

Can you show a picture of reverse side of nest thermostat? There is wiring diagram please take photo and upload so I can understand?

Re: E19 wiring report Y2 wire without Y1 wire

CoolingWizard — Thu, 04 May 2023 16:16:19 GMT

The simple answer is yes. Your two wires would be Rh and W1. You have no common wire, so you might have to add a power adapter and a third wire attaching to C. By chance, can you take a moment and upload the picture of your old thermostat with the wires attach so I can see what it look like? Try this, on the Y1 and the Y2, push buttons, push it down and quickly release it like snap your finger nail off of it let it pop back up. What the nest back plate is telling the display is there is a wire inserted in Y1 and Y2. From the photo there’s clearly not but for some reason the push button underneath there is not making contact showing the display that there’s nothing there. Hopefully you can just flickered a couple times and straighten it up.

AC Cooling Wizard

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 16:18:45 GMT

Can you tell me does the power adapter install at the boiler location? Will a third wire need to be pulled between boiler and thermostat?

Re: E19 wiring report Y2 wire without Y1 wire

CoolingWizard — Thu, 04 May 2023 16:24:22 GMT

@thombre55 , the tricky part is that some older boiler type furnaces, actually use a simple two terminal connection to turn on the boiler. It’ll be marked T & T. There is no common per se. So the answer is yes, we would need to pull a third wire, or what I would do would be to replace the current thermostat cable with a five or seven conductor cable. So if you find out that you need to have a common wire., you would have to put in a new thermostat cable, add a 24 V AC transformer, a relay. Then your thermostat would control the relay and when you sent a call for heating that would close the relay in the relay would connect the T to T and the boiler would start.

Truly understand your boiler I would need you to give me a picture of the boiler and the control system where the thermostat wires attached downstairs at the boiler so I can determine what might be able to be done easiest. It looks like you have a nest learning thermostat and that’s gonna have to have power to keep the lithium ion battery charged.

AC Cooling Wizard

Re: E19 wiring report Y2 wire without Y1 wire

MikePage — Thu, 04 May 2023 16:31:13 GMT

I did include that picture along with two others in my post. I think you may need to expand the post to see it all.

Re: E19 wiring report Y2 wire without Y1 wire

MikePage — Thu, 04 May 2023 16:31:54 GMT

I did include that picture along with two others in my post. I think you may need to expand the post to see it all.

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 16:43:47 GMT

The third wire will connect to Y2, between power adapter and Nest thermostat? Can I use a blue wire for the common third wire?

Re: E19 wiring report Y2 wire without Y1 wire

CoolingWizard — Thu, 04 May 2023 17:14:55 GMT

@Patrick_Caezza is a PE on here that has a few examples that will show the wiring of the boiler and the addition of a transformer and and relay. Perhaps he can share this with you.

AC Cooling Wizard

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 17:54:29 GMT

The three wires are power, heat, and cooling

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 18:09:59 GMT

I will pull back the existing two wire cable and replace with either a 5 or 7 conductor cable to feed the Nest thermostat. Thanks for your help

I will install 24vac xfmr along with relay at the boiler control box.

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 18:21:19 GMT

I will feed the spst relay from load side of 24 vac transformer. The T terminal of boiler will feed through relay normally open contacts, will close on demand from Nest thermostat, to cause boiler to turn on for heat. The same scenario will apply to cooling needing a second relay for cooling.

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 18:52:42 GMT

Hello Mike,

Can you zoom in before you take pictures. The clarity is blurred. Thanks

Re: E19 wiring report Y2 wire without Y1 wire

MikePage — Thu, 04 May 2023 19:55:06 GMT

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 20:25:11 GMT

Thanks Mike,

Very good , pictures are legible

Re: E19 wiring report Y2 wire without Y1 wire

thombre55 — Thu, 04 May 2023 20:29:28 GMT

https://widgets.nest.com/nest-thermostat-troubleshooter/?hl=en#e89

Re: E19 wiring report Y2 wire without Y1 wire

MikePage — Thu, 04 May 2023 21:45:11 GMT

Unfortunately, the website says error codes e89 and e19 (codes I got) are not valid. Not sure what to do about that.

Re: E19 wiring report Y2 wire without Y1 wire

CoolingWizard — Thu, 04 May 2023 23:40:28 GMT

E89 is The Nest Thermostat is physically detecting a Y2 wire but not a Y1 wire that is required for 2 stage conventional cooling systems or 2 stage heat pumps.

I do not have a listing either for the E 19 error

AC Cooling Wizard

Re: E19 wiring report Y2 wire without Y1 wire

MikePage — Fri, 05 May 2023 11:57:43 GMT

There is no wire connected to Y2. I only have power (white) and heat (red). This can be seen in the photos I posted.