When the weather is mild (-5C to 5-10C), my heat pump has a really hard time recovering from the lower temperatures set during the night and even has a hard time keeping up during the day. I’m not sure how much control the Ecobee has over this (might be defrost related? although I don’t see any ice on the heat exchanger) and it might be purely on the heat pump side. Is there something wrong here? The heat pump is able to keep up just fine without aux when it’s -25C outside.
Do you have Smart Recovery enabled?
How many degrees set back @ night?
Single or multiple stage heat pump?
Vari-speed fan?
Ecobee has little to no control over the effectiveness/efficiency of the heat pump. While smart, it really is just a switch.
If it has no issues at -25C, then something seems off. I’m thinking staging.
Smart Recovery is enabled yes. However, the temperature is modified via HomeAssistant so it won’t start heating early to be at the target temperature at a given time. That part is not an issue since the temperature is changed early enough.
2.5C, 21.5 during the day, 19 at night.
Single stage heat pump and I believe single speed fan.
Yea it might not be related to the Ecobee at all, I tried increasing the minimum runtime for example and it just overshoots the target temp and still randomly has a hard time recovering in the mornings. However, recovery isn’t the only problem, it seems like around freezing point, it has problems even keeping the temperature stable. I’m wondering if it’s because of the extra outdoor humidity causing more freezing, causing the heatpump to run defrost cycles and the ecobee doesn’t turn on aux while the unit defrosts.
Ecobee’s “staging” config is set to Auto right now.
The past couple of days have been horrible. Also not the end of the wednesday, not in recovery but still can’t handle it.
Still far from being very cold outside.
You have to be careful with Auto staging. Default for the heat strip changeover is set fairly high. You might not be seeing as much of an issue in colder weather if the heat strips are running.
You might also need to set the defrost to a shorter interval.
Yeah, your Thursday AM was pretty bad.
One other thing that stands out to me is Ecobee should overshoot set temp by 0.5F. I see areas where it is shutting off before desired temp is reached.
What is Home Assistant doing?
Looking at the ecobee website, the heat strips doesn’t kick in at all in colder weather:
“You might also need to set the defrost to a shorter interval” Might be the case, I’ll have to figure out how that’s done on my unit. I guess it has to be done on the unit outside.
Yes, that is a heat pump controller thing. What role is Home Assistant playing? It can’t modify the temp that the ecobee sees.
What does beestat look like?
I don’t see Smart Recovery showing.
What is purple on that ecobee graph. Mine shows Orange for heat, white for fan, and red for Aux(heat strips)?
Home assistant just has rules to set the temperature. The Ecobee was not good enough to deal with hot days + cool nights in auto mode so I wrote some rules that take the outside temp into account and switches it from cool to heat and back automatically.
Smart recovery wont show because the temp is set by HA so it can’t predict it.
Purple is the humidifier.
This is Feb 24th:
The AUX at the end around 0C is likely me setting it to AUX because it doesn’t keep up. Sometimes giving it a little boost helps it recover.
AUX is only useful when it’s around 0C it looks like:
It runs less at -22C than -4C and I have to manually give it a boost with AUX:
Also might be interesting?
I measured the temperature of the discharge line (outside of the copper pipe) at 52C.
The liquid line is much cooler, roughly room temperature.
March 18th: Outdoor temp at -12.3C, beestat shows “System Mode: Heat” (not aux) and Aux time isn’t displayed (so 0min is assumed)
4:00 to 4:30 → 1C gain
4:30 to 5:00 → 0.7C gain
My electricity bill shows 18kWh for that hour.
Feb 23rd: Outdoor temp around -6C. No aux time. This specific day I tried to keep the temperature at 21.5 degrees overnight.
The heatpump ran for 6h12 between ~1am and ~7am (so continuously)
Temperature hovered around 21.0 and 21.3
4:00 to 5:00, the electricity bill shows 4.65kWh.
While the heatpump doesn’t keep up, it also consumes less energy? It’s a single stage heatpump (Amana ASZ160301)
March 21st, I set the unit to AUX overnight. Recovering from 19C to 21.5C took about 1h40mins at -4.0C. The electricity bill for 4:00 to 5:00 was 17.66kWh for 1.8C indoor temp increase. Surprisingly very similar to March 18th in terms of temp increase and power used.
Is White the fan? Looks like it is running constantly.
Does seem like odd heat & Aux behavior. You would think it would run more in the colder temps. Most heat pumps, especially older, can’t even keep up at -10C.
I would certainly investigate what the unit’s Defrost parameters are.
I also see that the Amana may have an outdoor thermostat. It could be that your air handler is using heat strips without ecobee control.
Heat pumps definitely use less energy than heat strips.
I do keep the fan on 100% of the time. It’s less distracting if it doesn’t start/stop and it provides good air circulation throughout the house.
I’m trying to figure out the details on how the heatpump+strips are controlled to see if there’s a secondary control. This is a relatively recent unit and I’d expect it to be good enough at -15C to run without the strips but if it engages them without my thermostat being able to see it then it completely falsifies my data.
That being said, there are times where it shows up and the unit was in regular heat mode.
Looking at the unit’s specs, it mentions min circuit size 18A and min voltage of 197V, so I suppose ~3.5kW consumption, which maps well to what I see on my electricity bill.
Combined with the discharge pipe temp of 51-52C and the liquid line ~ room temp, is this 2.5 tons unit just undersized for heating?
Heating specs for an ASZ160301L do show down to -20C. But, only 4,800 BTU/hr output at that temp. Look at what your air handler is and what it is doing. That’s where the heat strips are.
