No power to nest thermostat

[Zachcaron88]

Hello,

The breaker that my nest is plugged into tripped today. When I reset the breaker I discovered I now have no power to my nest and keep getting error e195 no power to r wire. The breaker tripping was caused by another appliance not the nest. Any idea what could have happened when to breaker tripped to have caused this? Our nest has worked fine for like the last three years. Any help is appreciated!

[CoolingWizard]

Zacaron88,

This is very odd. Your thermostat should be getting power from the HVAC Equipment and that equipment should not be sharing power on a circuit breaker with any other appliances or equipment.  If you have a split system, you have and indoor unit and an outdoor unit.  In a split system the step-down transformer is located in the indoor air handler/furnace. If you have an HAVC packaged unit, the entire heating and cooling are located outside.  
Do you have access to the HVAC equipment? 

The AC Cooling Wizard

[Zachcaron88]

You are correct my furnace is not sharing a breaker with any other equipment. The nest itself is what is sharing a breaker with the outlet that tripped earlier today. This is a forced air furnace. I’m sorry I’m not very knowledgeable when it comes to this topic. 

[CoolingWizard]

Zachcaron88,

Please allow me to explain how this all works.  Located in the Furnace cabinet is a step-down transformer that is used to take the 120Volts AC or 240Volts AC and bring it down to 24Volts AC for the control system.  This 24VAC is used to power the Integrated furnace control board and to send power to the thermostat on the R wire.  We identify this R terminal in your thermostat as the Power IN.  

Based on your temperature settings and mode switch, the thermostat initiates a call for heating for cooling by internally connecting R to Y for cooling or R to W for heating. The other important terminal is the C terminal referred to the COMMON.  Smart thermostats need power for the electronics contained within. Like a light bulb or a wall outlet in your home it takes two wires to work. They are the LINE and NEUTRAL. The transformer outputs these as well.  The Neutral is the COMMON and the LINE is the Power-In on the R terminal. Why do is HVAC guys call it a COMMON and not a Neutral? We take the neutral and connect to one side of all the have electrical control devices. Therefore it is common to all the components.  We need this COMMON too for the thermostat and that is C terminal.  

now the nest is a pretty smart device, and the third generation nest does have the ability to find the common using that Y or the W in come cases and thus get that common path back to the transformer.  However, if the integrated furnace controller is a more advanced digital control board this will not work and we physically need a C wire.

OK now back to your problem. If your thermostat is not getting power right now, it means that your HVAC step-down transformer is not working properly or is not receiving input power.  Do you have access to the furnace? 

The AC Cooling Wizard

[Zachcaron88]

Thanks for the detailed explanation! I do have access to the furnace but do not know where my transformer is located. 

[CoolingWizard]

Zachcaron88,

here what to look for.  Standing in from of your furnace, you will see where the either two panels, or maybe two panels with a third shorter panel.  Look for where the power and the thermostat wire enter the cabinet.  That is the the panel you will want to remove.  However, please turn off the power before you decide to stick your hand inside the open cabinet.  What we are going to look for is the control board and the transformer.  Most control boards have an LED that flashes a code or a slow blink as a sort of a heartbeat.  On the inside of the cover your removed should be a label that describes that LED and how to interpret the blinking pattern.  Do me a favor and find the manufacturer label on the side of the furnace cabinet and give me the make and model number so I can pull out  the manual. 

The AC Cooling Wizard

[Zachcaron88]

It’s a thermo pride OL11-112 with a model AF Beckett burner. I see what could be a light on the front of the Beckett burner but it is not illuminated. There’s also a small Honeywell box situated on top of the burner with some wires. Maybe that’s part of the control board and/or transformer?

 

[CoolingWizard]

Oh my, you and oil fired furnace and that changes things.  Ok, so I need to see a picture of the thermostat cable and where it goes inside the cabinet.  Can you do that for me? The Honeywell box is the control part. See if you can get me a model number of the Honeywell box. 

The AC Cooling Wizard

[Zachcaron88]

No model number on the Honeywell box that I can see. Here are a bunch of pictures, hopefully one contains something useful. Thank you!

 

 

 

[CoolingWizard]

Your system is NOT and 24VAC control system.  What your system does is wait for a connection between the two terminals marked T on the Honeywell.  When the T is connect to the other T, that turns on the burner.  Your Nest thermostat must be an early model that uses batteries for power.  The 2nd Generation and 3rd generation learning thermostats are not compatible with your system.  The Furnace itself operates on 120VAC.  The red wire and the white wire attached to the T’s, are what are routed to your thermostat.   Now some of the newer furnace controller do indeed work with 24VAC and would be comparable.  Press the red reset button on the Honeywell and reset the controller then see if the power returns.  

The AC Cooling Wizard

[Zachcaron88]

We have never ever had to put batteries into our nest. This is the first time in over three years we have had an issue with the nest not receiving power. 

 

 

 

 

[Zachcaron88]

The Nest also loses power when we shut power off to the furnace over the summer. It has always come right back on when we turn power on to the furnace in the fall. 

[CoolingWizard]

Press the red reset button on top of the Honeywell and reset the internal controller.  

[Zachcaron88]

That fixed it! Going to be honest I wanted to hit that red button a few hours ago but the wife told me no 🤣😂. Thanks so much for all of your help today, it is very much appreciated!!

[Zachcaron88]

Well I spoke too soon. Hitting the red button returned the power to the nest but the furnace kicks on for roughly 45 seconds before then shutting off. If we hit the red button again it turns on but once again it stops working 45 seconds later. 

[CoolingWizard]

The furnace does that when the rest button is pressed. The system goes through a self check then goes to the ready state provided nothing is found wrong.  However, if something is deterred to be incorrect, or not operating within specifications, it caused the controller to trip. Keep your thermostat off for now, press the reset, then wait for a couple of minutes. If the controller does not trip, then turn the thermostat on, select heat, choose a temperature 3-degrees above current room temperature and see what happens.  

The AC Cooling Wizard

[Patrick_Caezza]

You need to add the Google Nest Power Connector and an external 24Vac transformer to your system.

You have a Nest Thermostat E installed, and it uses a power-stealing setup to keep the internal battery charged. The problem is that two-wire-only systems don't work very well with the power-stealing setup, and the battery can't keep it charged enough after a few years.

By installing the power connector and external transformer, you create a much-needed C wire, and the thermostat will stay fully charged all year

[CoolingWizard]

Patrick, that Honeywell controller produces 24 V AC on the T connector it looks for the 24 V to come back on the second T connector.  This controller is very similar to the Honeywell R8185E 1032 Protctorelay Controller.  While a power connector would be useful, it will require a service technician to open up the Honeywell and attach a wire to the common side of the internal transformer.  

The AC Cooling Wizard

[aatienza]

Hey Zachcaron88,

Checking in — we hope you've got the answer you're looking for. Let us know if you have more questions in mind.
 

I appreciate the help, Patrick_Caezza and CoolingWizard.

Thanks,

Archie

[aatienza]

Hey there,

I just wanted to follow up to see if you still need our help. Please let us know as we would be happy to answer any questions you may have. 
 

Thanks,
Archie

[aatienza]

Hello there,

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
 

Thanks,

Archie