Earlier this month we took a 10 day trip out of town to visit family. Before we left, with the help of Sense, I went around and ensured all of the major energy consumers in the house were turned off. This included our interior lights, turning the HVAC to vacation mode (essentially turned off as it didn’t run for the entire 8 days were were away), as well as using the Sense app to power off my various smart outlets in the Home . During this time we generated about a 500kWh surplus of Solar, feeding back into the grid to offset future usage.
Upon returning I reversed the process. Powered back on the shut off outlets, turned the HVAC off of vacation mode etc. I did this an hour or so out so that our Florida home would have time to come down in temperature before we arrived. When I got home I noticed something a bit strange, I was suddenly receiving notifications that I was hitting all time energy usage highs. Previously, our all time high was around 26,000 watts. This was a combination of Charging one of our Teslas (11.5kW), our HVAC running (3.7kW), our Oven (5kW), and our Electric Dryer (5.2kW). The spikes were in the 30,000 watt to 35,000 watt range and they kept increasing. The strange thing is that Most of those items were not running. I was a bit perplexed. I headed over to the Sense app to take a look.
What I discovered is that sometimes, but not every time, it was taking longer that normal for my HVAC to fully start up. The fans were kicking on, both inside, and at the HVAC condenser. What wasn’t kicking on was the compressor inside the HVAC condenser. It was trying to start but instead it would only buzz. After a few tries it would eventually start and the unit ran fine. When that was happening I was seeing VERY abnormal spikes in power consumption. here is an example below of the HVAC trying to run, but taking almost 10 minutes for the compressor to start. This is a nice example because the rest of the house was quiet energy wise. Only lights, my computer/monitors, and ceiling fans were running.
As you can see from the image there were 11 abnormally high spikes over an almost 15 minute period before on the 12th attempt the compressor started and the HVAC ran normally. I called our HVAC installer and they scheduled someone to come out. They were backed up and weren’t able to come till yesterday. The HVAC is covered under the new construction 2 year warranty still so I had to wait for the installing dealer, otherwise I’d not be able to take advantage of the warranty. The spikes continued to happen. They seemed to happen more often after the HVAC had been off for a longer period, but each time the HVAC would run so we were ok to wait. During the wait, the Sense Labs Motor Stall section began reporting motor stalls. The system was smart enough to also recognize the energy spikes I had seen and spot the same pattern I had a day or two earlier. This is a great feature that helped alert me to a pending failure, before the failure was a complete one.
Within a couple of minutes of the technician arriving, I explained what was happening, showed him the graph from the Sense app of the power spikes, and he headed out to check the capacitor for the AC compressor. He immediately said that it was the problem, grabbed a spare from his truck and from that moment on, the HVAC stopped spiking and failing to start.
If it weren’t for having my Sense unit installed, we likely wouldn’t have noticed anything was wrong till the capacitor completely failed. This would have left us without HVAC at some unknown point in the future. It wouldn’t be so bad if it happened from now till March when Tampa sees it’s “winter”, but could have been brutal if it happened any other time of the year.
