No Power to thermostat and relying on Batteries


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Old 08-26-12, 03:20 AM
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No Power to thermostat and relying on Batteries

So, I have a 3 zone heat gas boiler heating system in my house. I wanted to replace all of thermostats with Nest theromostats (Nest | The Learning Thermostat | Home). The first two, I replaced without an issue, however, the third is giving me fits. I first realized there was a problem when I took the batteries out of the existing thermostat and it completely powered down. This indiciates my thermostat is completely relying on batteries for power and If they die in the winter and I am away for awhile, my pipes can freeze. This is not good! I still went ahead and tried to install the Nest to see what would happen and it confirmed my suspicions about having a power issue.

There were 2 wires connecting my existing thermostat, an RH a W. When I connected the Nest to it, it kept rebooting and powering down. I then noticed I had a third black wire that wasn't connected to my original thermostat. I thought maybe this was the Common Wire ground wire and and I can try that. When I connected that, the Nest kept throwing this error E4 (Nest | What do Nest's wiring errors mean?). I have another thermostat downstairs with RH and W1 wiring and the Nest works fine. For some reason, this identical setup with the thermostat in my bedroom does not work as it seems to be some sort of power issue which I need to rely on batteries.

Thoughts? Any help is appreciated.
 
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Old 08-26-12, 07:25 AM
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it depends on the type of zoning you have. More than likely what is happening is the your type of zoning is just using dry contact inputs. Nest has a long way to go to be a reliable thermostat in my opinion. I hear of nothing but troubles with the NEST when there is not a common wire used so that the stat is relying on trying to charge through stealing power from the circuit as it call for heat.

Back to your problem. I would suggest either a different thermostat or you will have to give us more details about how your system is zoned...make and model of zone valves, or is your system zoned with pumps, if so it will have a zone controller.
 
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Old 08-26-12, 08:24 AM
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Thanks. I actually called Nest tech support and he had me put back the Nest and see if I can get power readings and ironically, they are now good and everything is working. I have no idea why I had trouble initially, but everything seems to be working now. Their tech support told me it's normal for a lot of programmable thermostats to depend on batteries. I had no idea.

I can't comment on Nest yet, as I just installed two in a brand new house. I will say I love the fact I don't have to program thermostats anymore as it senses when we are away and I love being able to control temperature from my phone or computer.
 
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Old 08-26-12, 11:23 AM
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Honestly, if you program a stat once you should never have to do it again... its just plainly how we as a society have become so ridiculously in a hurry that we cant spend the 5 minutes it takes to read a manual and program a thermostat. I've heard it all as far as my schedule is constantly changing....or I can't even program my VCR. It's plain laziness. The NEST could actually end up costing you even more money in utilities depending how IT decides to operate your system. Some features such as internet access are nice, but are they really necessary? In my opinion there are much better thermostats available that are better suited for systems than the NEST (each type of system should have a thermostat that is capable of correct and proper operation of said system). Only then can you be certain that your thermostat is controlling the system to best ability possible. To spend $250 on a thermostat for a simple installation/system as yours is a waste of money in my mind.
 
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Old 08-26-12, 11:58 AM
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I completely agree with hvactechfw.

Now that I am retired I could never have a programmable thermostat that I could live with. I don't want my thermostat to turn the heat on because it is 67 in the house and I programmed 68. Amazing as it may seem, I DID turn the heat on for a while yesterday after the sun went down but I also turned it back off when I went to bed. NO thermostat, I don't care how much it costs, how much it may try to "adjust" to my lifestyle or whether it can be accessed via Internet will be as good as my right index finger pushing the raise or lower temperature buttons.

IF, however, a person/household is on a VERY regular schedule AND can't be bothered by manually setting the thermostat, THEN using a programmable makes sense. But from what I have seen/read of the Nest the absurd cost factor will negate any real savings.
 
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Old 08-27-12, 05:55 PM
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I gave up on my Honeywell programable t'sat. It worked as advertised, But-

When we left town for a day or a weekend, I had to consult the manual to figure out how to reset it. Sometimes the cat was left at home, and other times he was farmed out. Then there is daylight savings time. My Honeywell supposedly took account of that - at least until the federal government changed the start and stop dates.

Power outages, dead batteries, etc. Different wake-up times based on the night before. Late night arrivals home. Ridiculous.
 
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Old 08-28-12, 05:48 PM
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I have to agree with the others. A programable stat is more stinking trouble than it's worth. In my small house I have 4 thermostats, three of which are programable & two programed. Those 2 are the bedroom & addition. Bedtime is pretty stable & the addition isn't used during the day. Do they save me any money? I doubt it.
 
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Old 08-28-12, 06:45 PM
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Geez. I didn't think a programmable tstat could be so hated. I have a simple programmable stat. You can set a schedule for the week and another one of the weekend. When I don't want it to run on the schedule I just exit out of the programmed schedule. Pretty easy stuff. Of course I only use this for the a/c. In the winter I keep the temp at 70. Turns out I save money that way.
 
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Old 08-28-12, 07:10 PM
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I don't hate programmable thermostats, I just know that the claims made by those that sell them (or want you to install one) are often quite unachievable.

My city, or maybe the county south of me that seems to be the source of many of our city's ordinances, (Bothell straddles the King-Snohomish county line) specifies full seven-day programmability for any thermostat installed after some certain date. I have a seven-day programmable thermostat and it might even have a program set, I don't know. I haven't used the programmable function since I retired because I don't follow any kind of regular schedule. When I was working I DID use the program feature. I have little doubt that I did save something when it was in the programmed schedule mode. What I do now, or at least during the heating season, is to turn the setting down to 62 when I go to bed, turn it up to 68 when I get up, turn it down if I decide to go out for more than maybe a half-hour, turning it back up when I return, turn it up to 70 some time in the early evening and then back down to 62 when I go back to bed. The temperature set-backs are the same but the times of the set-backs vary widely. It works well for me but might not work at all for someone that can't remember to adjust the thermostat on a regular basis.
 
 

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