Nest - Won't keep Boiler On

[mobiledynamics]

I'm sure some fellow bethern GJ member knows the answer....

We've got a nest thermostat on our hot water heating system.
Damm thing will keep the pump running but it shuts off the boiler, so the water passing through the pipes is not -hot enough-. I think it's just their way of ECO algoritim.

I don't see anything in the options on the Nest to tweak it.

Figuered I'd cheat it. Instead of 72F, I set the knob to 80F. Boiler kicked in, and was on for about 10 minutes. Now it's back to simmer.

 

[LB-1911]

Quick question -

Have you been here yet?

How to tell if your system is Nest thermostat compatible and get a wiring diagram

 

[yeldogt]

How is you system wired ?

Baseboard ? Radiators?

So the nest has twin outputs for both circulator and boiler?

I to constant -- so there is always base heat in the radiators. Many baseboard system have an end limit on the zone valve that turns on the boiler?

 

[mobiledynamics]

Constant. Baseboard. I found it I think. Must be a new setting, as I don't recall this back eon's ago when I installed in.

Under setting, under True Radiant. Right now boiler is on, even with 3 degree delta difference on current temp vs. set temp. Literally, 20 minutes prior, indoor was at 70 and I cranked it to 78 F, and it only kicked on for 15 minutes top.

----

Sadly that did not do it. In thinking the setting need to kick in, once the nest was off cycle, I dialed it back to 66 and then turned the knob to 72. That turned the boiler on but went off after a few minutes. Figuered I'd do a round 2 test and crank it to 78 like prior. Boiler still does not cycle on. 10 minutes later, looks like at 78F on the dial, the boiler has decided to turn on. Will see how long it stays on...

 

[Jsf721]

I just got off the phone with Nest tech support. They will verify compatibility and feature set if you go to the website click chat you can upload a pic into the chat and show them the previous wiring diagram. Perhaps they can help. 1-855-469-6378 is their call on number but the wait said 30 min and was actually 17. Good luck

 

[mobiledynamics]

I've had the nest for around 18+ 24 + ?
Not really a issue on mild winter days. Just need that boiler on more frequently on days like today

 

[yeldogt]

What type of boiler are you running constant circulation with baseboard?

What did you use previously?

Constant circulation typically uses outdoor reset with the thermostats acting as a high limit -- I don't even have thermostats. It's all based on heat loss and boiler curve.

Are you sure you don't have it set up so the system starts with the nest and then it using the boilers setting ? it may not be set high enough for colder conditions.

 

[LS6 Tommy]

It could be the minimum off time settings.

Tommy

 

[Stuff]

First I would verify the boiler is working right. Remove the Nest and short the R and W wires together and see if the pump and boiler work as needed.

Nest only controls one wire W1 and doesn't know what it is turning on. In some cases it doesn't fully turn the W1 on and you get problems like described. Usual fix with Nest is to get a C wire connected to the thermostat so it doesn't try to steal power from the W1 connection. Sometimes without a C you can swap R and W to fix the issue. If you already have a C wire then you may need an isolation relay.