Shaun Merrigan's Information Pages

Tag: learning thermostat

NEST Thermostat Update and Voltage Measurements

Posted by Shaun Merrigan in NEST Thermostat, News, Tech. 1 Comment

18th November

NEST Thermostat Update and Voltage Measurements

I have had my NEST Gen1 for almost 16 months now and I probably could not go back to a regular dumb thermostat, given the choice.  The NEST charging problem has been solved by connecting the “C” (AC Common) wire from my furnace to the NEST.  See this post for details: Nest Thermostat Charging Solution

I find the monthly NEST Energy Reports very useful, and I am saving them so that when I make important changes to our house (new windows, more insulation, more efficient furnace, etc) I can see an actual difference.


I thought it would be helpful to anyone still troubled by the charging problem if I posted my NEST reported and measured voltages:

Furnace running (heating) NEST Reported Voltages: Voc 38.33V, Vin 31.57V, Vbat 3.864V, Lin 100mA (i)

Voltage measured between Rc and C (Power and … Read More »

NEST Thermostat Functioning Well after Wiring Change

Posted by Shaun Merrigan in NEST Thermostat, News, Tech. Comments Off on NEST Thermostat Functioning Well after Wiring Change

16th March

NEST Thermostat Functioning Well after Wiring Change:

Over a month on since I changed my NEST v1 thermostat wiring to include the “C” or 24Vac Common wire, it is working flawlessly again. We have had several cycles of cold (-20C) and warm (+8C) and there have been no problems with charge levels, network communication or connectivity.

I wonder why NEST does not strongly recommend the use of the “C” wire when it is so simple to install? BTW, if you are looking for a wiring diagram of your furnace and controller, check the back side of the access panel (Doh!!) on the furnace; it should be there.

I have e found a couple of very useful links for anyone in a similar situation and seeking a solution:

Adding a C wire to a Thermostat


Shaun M

Nest thermostat battery charging problem and solution

Posted by Shaun Merrigan in News, Tech. Comments Off on Nest thermostat battery charging problem and solution

7th February

Nest thermostat battery charging problem and solution

My NEST (Generation 1) had been working flawlessly for several months, both summer and winter (heating and cooling) until about January 23rd, 2013 or so. Then it began to struggle with recharging, had network dropouts, disconnects, and began to insert Delay Times (apparently randomly, and up to 2 minutes in duration) into the heating cycle. I recharged the NEST using the USB interface a couple of times, only to find that it would run down within 8 or 10 hours and never recharge. With -25c temperatures for days on end, the last thing you want are strange delays and the resultant furnace cycle down/up and an unreliable thermostat. In fact one day with -40c windchill, the furnace would run for about 10 minutes and then cycle off as NEST inserted a Delay Time for … Read More »

NEST Thermostat Update

Posted by Shaun Merrigan in News, Tech. Comments Off on NEST Thermostat Update

21st December

NEST Thermostat Update

From November 30 to December 12 we had no wired internet connection. Therefore the NEST thermostat could not connect to via our network. I found I had to turn off the NEST’s network connection so that it would not run down its internal battery constantly trying to connect to a non-existent network (Note: to the NEST team; this should be addressed). At no time did I ever lose local control, however. The NEST simply behaved like a typical sophisticated programmable thermostat. We have been experiencing one of the coldest winters in the last few years, so I can readily appreciate the very useful features of the NEST such as: tweaking the temperature from my iPad, making schedule adjustments via the iPad and viewing our energy usage.

NEST Thermostat Update

Posted by Shaun Merrigan in Tech. Comments Off on NEST Thermostat Update

16th November

NEST Thermostat Update

Winter is certainly here now, and the NEST thermostat has been performing well. I have had some issues with my ISP and DSL modem which have prevented the NEST thermostat from connecting to the web for 12 or more hours, but local control has been maintained throughout. This is a good sign, and indicative of well thought out design. I have a V1 Nest, which does not include humidity control. However, I think that my solution: a dedicated humidity controller with an external temperature sensor is probably superior anyway. In my cold climate, we absolutely need an air intake temperature sensor to regulate the humidity. Think about this at -25C….

My gut feeling is that my house is more evenly warm now that in was with the conventional programmable thermostat (Honeywell) that I … Read More »

Nest Thermostat Update

Posted by Shaun Merrigan in News, Tech. Comments Off on Nest Thermostat Update

10th October

I was pleasantly surprised to see that my NEST Gen 1 thermostat updated itself to the latest software (V3) last week. This added a couple of new features like filter change reminder based on hours of use(forced air heating), energy use comparisons to similar house builds, Early On, Auto Schedule in Heat/Cool mode and several other new features. This is the same software that was rolled out with the Gen 2 Nest Thermostat, so I am not feeling left behind.

There were no issues transitioning from cooling season to heating season. We typically have 4-6 weeks in the fall and again in the spring where heating and cooling is not required, and we are just now getting into the heating season. I have had no issues at all with the NEST: Network connectivity has been … Read More »

NEST Thermostat update

Posted by Shaun Merrigan in News. Comments Off on NEST Thermostat update

17th July

The NEST thermostat has been operating faultlessly since I did the wiring reseat and SSID fix. We have had some very hot weather and I have been using the AWAY/AUTO AWAY modes, so I really appreciate being able to remotely cool the house down before arriving home. I also received an email from NEST showing me my cooling usage for the month of June. In aggregate, over time, this information will be very useful.

I am just finishing up the installation of a digital humidistat as the NEST has no provision for controlling humidity. I knew this before purchasing it, of course. I needed to upgrade my old wall mounted mechanical humidistat to a digital unit with a remote sensor on the fresh air intake in any case. This is particularly important in a cold … Read More »

NEST Thermostat

Posted by Shaun Merrigan in News. Comments Off on NEST Thermostat

24th June

Further updates on my experiences with the NEST thermostat:

Although it is possible to enter a Canadian Postal Code using the NEST itself, I found that I could only change the geographic location ( City, Province) using the WEB app. The geographic location could not be changed using the iOS NEST app either, as that option is not made available. Having said all of that, once I made the changes using the WEB app, the proper location appeared on my NEST thermostat.

Had a problem earlier in the week with the NEST dropping my wifi connection and the battery not recharging. I did two things which solved the problem: first I reconnected all of the thermostat wires by pulling them out of the base plate (while pressing the release) and then pushing them back (not touching the release) to make sure … Read More »

NEST Thermostat

Posted by Shaun Merrigan in News. Comments Off on NEST Thermostat

2nd June

I installed a NEST learning thermostat ( this weekend.  No issues with the installation on my 2 stage heating 1 stage cooling, forced air HVAC system. I tested both heating and cooling and all worked fine. There are several problems which I have solved which may help other people who decide to install the NEST themselves:

1) The NEST will not behave as expected if the battery voltage is <3.7 volts.  For example, I thought that the proximity sensors were not functioning, and that I had some obscure network connectivity issues upon first installing the NEST. The NEST would not dectect me as I approached it (approach detection enabled) and kept dropping my network connection.  It turned out that ALL of these problems were related to the battery voltage being < 3.70 volts.

2) I could have waited several hours for the … Read More »