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Nest Thermostat Install

5K views 34 replies 12 participants last post by  airtrackinc 
#1 ·
What could I possibly be doing wrong- it won't power up. Red - W, black Rh. Steam radiators....works fine if I hook the old one back up. Plugged nest in to USB to try and charge- it boots up and says to connect to base.

 
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#10 ·
I went to their site and it is a bit vague. It says that on SOME zoned or hydronic valved systems it may need a C wire. Basically it is a power robbing/stealing thermostat and I dislike them and have had lots of problems with any brand of them . NOT a good idea and the C wire is always recommended.
 
#12 · (Edited)
Yes on some systems you need to supply 24vAC to keep it powered. Otherwise the batteries will go dead on the thermostat. Their site is not vague. All of the info is on there if you look.

The problem is not with the Nest Yuri. It is trying to do something that Nest states very clearly that you cannot do with their equipment at this stage. There is an installer screen, that allows you to do certain changes. The 2nd gen is the better one to get. The next gen is supposed to be even better. Due to certain improvements and lessons learned over the past two years.
 
#22 ·
Nest problem

I am a controls designer who as a part of my job have to verify compatibility with other companies' products. I had a terrible time dealing with the Nest product. Spent lots of time with their tech support. I know that the grounding of your transformer can be a big deal with Nest. You may want to verify that your controlled device (boiler) and control transformer have a common ground. Connecting the Common wire did not cure my problems.

If you Google "Nest thermostat Problems" you will see that there are lots of discussions about problems occurring with that product. It has been awhile since I fought with their product, but I can tell you that of all the web enabled stats I used Nest was the only one that gave me any difficulty. No one wants to hear advice that they should spend $120 bucks on replacing something they just bought, but one day worth of fighting will cost a lot more.

Regards,
 
#7 ·
Do you see the part that the 1st gen has issues with your type of setup. There is an installer mode, but may not properly work in your case.

Suggest contacting them. Their help line rep's are really knowledgeable and can help dig anyone out of problems. I have had to deal with them on three Nest Protects that were having issues. Two replaced, the other was due to false alerts. They know what they are doing, so make the call.
 
#13 ·
I have no problem as long as C is used. W/O it power stealing stats of ANY brand can damage circuit boards and with the mod furnaces you don't want to even go there. Not good industry practice to not use a C wire but in the DIY world and for profit from these manufacturers anything goes.
 
#14 ·
Yes you should not be stealing power from while the unit is running. But you are talking about people that do not know a Crescent Wrench from a Hammer, or a Phillips head screwdriver from a Flathead.

Every thermostat out there, including Nest now. States on the packaging that C is required for proper operation of the unit. Nest has learned a lot over the past three years of jumping into an area that the ownership saw as a niche market.

That is one reason why I went with wired Nest Protects, vs. the Battery operated only units. I personally do not feel like dealing with batteries going out after two to three years. It is bad enough that the one in my son's room goes off every now and then, due to current flow from the register below it. I have done everything to stop false alerts, but you just deal with it when it happens.
 
#15 ·
Thanks for everyones feedback...it seemed too easy.

It seems like the consensus is that it should work w/o a Common wire, but not recommended. It will only be used for heat during the winter.

Does anyone know if I go with one of the installers off the Nest website, will they run a common wire for me?

Is hooking up a common wire something I could do myself?
 
#16 ·
Personally I don't believe in using setback thermostats for hot water or steam systems. Both are designed to give you even constant heat. They are slow to recover and when you cool them down a lot you get a lot of expansion and contraction in the rads which is not good. They are not designed/sized to recover quickly so it is not a good idea. Of course Nest or others wants to sell you there product but the reality is different.

You would need to run a 18/2 thermostat wire from the boiler to the thermostat and that requires fishing the wire thru walls etc. If you want to pay several hundred $$ for an electrician to do it, the thermostat will never save that amount of fuel or pay for that IMO. If you know of one that you can barter with then it may be feasible.
 
#17 ·
I'm not too concerned on the return $ on the Nest as it was a gift. Honestly it's more for the wifi features and app than trying to save money. The thermostat is directly above the basement and is exposed so not a big deal to run the wire.

Do all boilers have a common hookup? Mine is probably 30 years old. The 2 wire runs to an old looking transformer with 2 twist knob hookups. I'll send pics next time I am home.
 
#19 ·
Yeah, modern boilers have transformers that have a specific Common terminal and some ground the secondary side of the transformer/C common. Has to do with electronics as to how that works. Your Nest may not be a good candidate for the old system.
 
#21 ·
You do not need to hire an installer. If you can use that current wiring to pull a 4-pair back up from the basement, for future proof. Then you would have the extra third wire for right now.

Now if you are going into the end of season. As the boiler tech that will come to shut the system down for the Summer, what it would cost to fish the new wire up to that location. Some are pretty cheap if you supply the roll of wire. Others will charge more. It all depends on how difficult it will be.

Things like these. I do for a 12 pack of some Micro-Brew beer. Plus have them help pull the wire.
 
#23 ·
My company does not sell them as we are a Lennox dealer and use our own high quality Lennox ( made by Honeywell ) stats as some of our units are VERY VERY expensive and we don't want conflicts or damage. We installed some Nests that customers bought but don't really promote them. Modern furnaces and circuit boards are VERY polarity and grounding sensitive and I suspect those Nests are too. When you get old steam boilers and old corroded wiring with cotton covered insulation etc I imagine that is where lots of the problems stem from. Poor grounding to the panel etc is probably a huge issue.
 
#24 ·
So regardless if I go with the Nest or another Wifi thermostat, I'll need a C wire.

The transformer where my 2 wires goes to is right next to my breaker panel, as well as 4 outlets. Can I get something like this to power my thermostat?

http://www.amazon.com/Class-II-Transformer-Approved-MGT-2440/dp/B004VMVDTA

Is the C run directly from that? Someone mentioned in the reviews that the red from furnace should go thru the transformer as well.

Will post pictures tonight. Thanks.
 
#27 ·
An update-

My electrician wired a 24v transformer ($35 at HD) so I now have a C and rc connection. Setup was a breeze and the Nest is working normally now. I definitely recommend it as you won't have to deal with battery issues.

Thanks everyone,

Kevin
 
#29 ·
Of course it is spring and almost time to shutdown the boiler...I'll check back when I have an update!

I did go with the first gen vs second as reviews seemed pretty bad. Wifi app is pretty cool but won't get a sense of "true radiant" heating unless temperatures dip.
 
#31 ·
I tried out a second gen Nest and took it back the next day after it locked up for no apparent reason. To the OP I recommend using a Honeywell tstat set to either 1 or 2 CPH. Forget the Nest.

In regards to not doing a setback with steam, I will agree to an extent, however I do a setback with my single pipe steam. I've done a 9 degree recovery and only cycled on pressure @ 1.5 PSI one time, 5 degree setbacks are not a problem at all.

I recently did a modification that ensures my pressure stays below 2 ounces so even a 10 degree recovery will no longer be an issue. This modification also eliminates all overshoot so I end up exactly at my setpoint.

As far as speed, my system will give a forced hot air system a run for it's money.
 
#33 ·
cj133 said:
I tried out a second gen Nest and took it back the next day after it locked up for no apparent reason. To the OP I recommend using a Honeywell tstat set to either 1 or 2 CPH. Forget the Nest. In regards to not doing a setback with steam, I will agree to an extent, however I do a setback with my single pipe steam. I've done a 9 degree recovery and only cycled on pressure @ 1.5 PSI one time, 5 degree setbacks are not a problem at all. I recently did a modification that ensures my pressure stays below 2 ounces so even a 10 degree recovery will no longer be an issue. This modification also eliminates all overshoot so I end up exactly at my setpoint. As far as speed, my system will give a forced hot air system a run for it's money.
CJ it sounds like you have an exceptionally well maintained steam system, which I tend to think is the exception rather than the rule. The conventional wisdom that steam doesn't do well with setbacks seems to be true far more often than not. If someone is putting a Nest or any other smart thermostat on their steam system the should do that last, after making sure the vents all work properly, the mains are insulated, the system heats evenly, the header is set up correctly and the system is well balanced. And if it gets to that point I would expect anyone would save more money by using a vaporstat to run the system on ounces of pressure rather than pounds of pressure (pressuretrol). I'd bet my breakfast the vaporstat saves more money than installing a Nest and using setbacks.
 
#34 ·
I completely agree. This is why I said "In regards to not doing a setback with steam, I will agree to an extent"

During the normal heating season I can get steam to every radiator in around 2-3 minutes after the burner starts. Pictures of my system can be found at the link in my signature at the bottom of this reply.
 
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