Can network loss put heat pump behind the curve?

We have a new heat pump system. This morning our Ecobee Premium thermostat appeared to lose connection to our network. By the time it restored the connection, the house temp had dropped a bit. Heat 1 came on, then Heat 2, then Aux Heat (heat strips)–and since it wasn’t that cold outside, the Aux Heat triggered a warning that something could be wrong.
Is it possible the Aux Heat came on solely because the house temperature wasn’t rising quickly enough after the network outage, or should I be worried?
Here’s the graph:

I probably wouldn’t be too worried about an aux heat run right after an outage. This looks like an ecobee outage as well, since the outdoor weather is also missing. A local outage would still have outdoor weather logged.

What I would do in your situation is take a moment to understand when to expect your aux heat to engage. This article might help.

Basically, the aux can come on due to a temperature difference being too large, or it can come on due to the heat pump running too long. Additionally, you can set lockouts so the aux doesn’t even turn on no matter what above a certain temperature threshold. My typical lockout recommendation is to set it near your system’s balance point.

Yes, I had read that article earlier and changed several settings accordingly. Configure Staging is now manual, with the minimum compressor temp down to 5 F because we only have heat strips for auxiliary heating, not a propane furnace. But the Aux Heat maximum temperature is 55 F.–I think that was the default setting, and it’s close to my current balance point of 51 F. (I could swear the balance point keeps changing, which I don’t yet understand.) I had thought that setting was purely hypothetical as the heat strips would “never” be called into action at such a high temperature, but after this network outage I realize that’s wrong! One follow-up question: You suggested Ecobee must have gone out too, not just the network connection (which happens all too frequently), because the outdoor weather info was missing. But isn’t that a network function? I thought Ecobee just relied on whatever weather station the installer told it to use, which is problematical for us–there’s no truly local weather station and the one in the nearest town has considerably warmer winter low temps than we do.

51°F?! Yikes. If you want to send me your thermostat serial number I can review what beestat says. I would typically expect this to be closer to 30°F, if not lower for more modern pumps.

All of your thermostat data is transmitted from your thermostat to the cloud every few minutes. If your Internet goes out, that data won’t transmit and your thermostat doesn’t store it forever, so the data gets lost. The weather, on the other hand, is all gathered by ecobee’s own servers. You put your address in, and ecobee does the rest. Since ecobee already has the info, however, they aren’t reliant on your Internet to receive that data.

So, generally, if you see a gap and everything, including the local weather is missing, assume it’s an ecobee cloud issue. If you still have the weather info, assume it’s a local issue.

The Ecobee Serial Number is 531615611430.

Use your second stage for your balance point:


At 34°F, your second stage heat can no longer keep your house at the temperature you set. I would set your Aux Heat Max Outdoor Temp to 34°F. Then adjust as needed. If it gets a little too cold for comfort at those temps, bump it up a couple degrees. That should keep the aux heat off unless it’s truly needed.

IIRC without weather data the Ecobee ignores aux lockouts as a just in case measure. It won’t know the outdoor temp because it lacks an outdoor sensor and frozen pipes are bad.

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That sounds MUCH better! Done.

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