It seems like my temperature profile is backwards for heating. The colder it is, the less hard the heater has to work to bring the temp up?
For reference this is what the Ecobee weather impact graph looks like
I agree that isn’t typical. What type of equipment do you use for heat?
95 AFUE Gas Heater 60k btu stage 1, 100k btu stage 2
The furnace staging is messing with the graph. The colder it gets the more often your second stage kicks in making it warm up faster at a lower outside temp. There could be other factors like unknown heat loss due to a damper stuck open. Another thing to look at is if you have a fresh air intake that is pulling too much cold outdoor air in and lowering your furnace’s heating capacity.
Is staging controlled by the Ecobee (W1 and W2 wired to stat and W2 delay disabled on furnace) or is it controlled by the furnace? Longer calls for heat when it’s colder outside that make the second stage kick in would cause this behavior too.
I’d recommend using the stat to manage staging instead of the furnace as the furnace is just a dumb timer.
Edit: you only have it wired as a single stage furnace according to the usage graph. It’s definitely not using the stat to manage staging.
The ecobee is actually controlling the staging. I just have it to set to 2hrs before the second stage kicks in, because I prefer the warm air circulating. So the second stage only kicks in on the absolute coldest of days.
These situations are always tricky. Initially I would have agree with @cscott92 that your second stage was controlled by your furnace. But if you are letting your ecobee control the staging then that wouldn’t be it.
With a gas furnace what you would typically see is the heat line mirrors the resist line, just offset upwards by a couple degrees. This is because gas heat is not affected by outdoor temperature, so the apparent effectiveness is matched up to your home’s temperature change.
I’m not too familiar with gas heat systems. Is it possibly that it’s running at a variable BTU where at higher temperatures it’s producing less heat?
It looks like you answered your own question then. You gave it an abnormally long delay to second stage so it’s basically a 60K single stage that runs stage two once a month. It’s pretty common for residential contractors to oversize equipment by a large margin because it’s easy to err on the safe side. You definitely got a poorly sized unit if this is close to your minimum design temp and it is running on 60k first stage intermittently.
Using something like reverse staging might work better for your use case where you have a 2 stage furnace that is oversized. You can just set it so the second stage is only used during recovery from a setback and then it doesn’t kick in unless your first stage can’t keep the temp within a few degrees of the setpoint. That way you don’t get the second stage kicking in when first stage is keeping your house at the setpoint even after two hours of continuous run time.
If the 2hr delay thing works I’d say just stick with it for now as reverse staging will probably reduce run times if that’s your top priority.
I also have a 2 stage furnace that only needs the first stage to maintain setpoint. However, I had to turn off the ecobee’s Smart Recovery for night time usage. With it on, I would call for stage one at 2a-3a in the winter in order to get to 68 by 630a. the second stage would not come on unless it was still too cold at 630a. With it off, I have furnace come on at 530a and aim straight for that 68, so both stages come on. I also turned on reverse staging (which I love). In the morning, once I get within a degree or so of setpoint, it drops back to stage one and slowly gets me the rest of the way to the setpoint.