I have a device that shows up as “Water Heater 2” that I’m not sure what it is. I’m pretty sure it’s not the water heater though. It averages almost 5300W and runs for almost 5 minutes. There is data for it going back to Nov 2019, but it’s only seen sporadically. It’s only been on twice a month except for Dec where it came on 3 times.
I live in Florida, so our heat doesn’t really run all that often. I suspect if I could look at the timeline to see what times the device turned on and off, it would be in the middle of the night when a cold front came through.
The data export was not helpful at all in this regards.
As a side note, I know I can use IFTTT to write an event to a Goggle sheet when the device turns on and off. This has a few downsides.
You can’t see historical data
If you want to see on and off you have to create 2 rules in IFTTT, one for each state
If it’s a device that doesn’t run for very long, sometimes the off event is written to the Sheet before the on event
This rule goes off the device name and not the device ID, so if you rename a device it messes up the rule in IFTTT and because of point 2, you have 2 rules to go edit and fix.
Have you lined the Water Heater 2 “ons” with the Mains Power meter?
If it’s only on twice a month it should be easy enough to have the Mains PM up while looking at an export or the Water Heater 2 PM.
I would suspect at that wattage that it is your water heater. Sense is missing the full cycle perhaps periodically due to something else activating at the same time.
You should be able to quickly figure out what your water heater wattage is by looking at the label or likely the peaks in the Mains PM. Most water heaters will run for well over 5 min to reheat after showers and heavy usage so look around those times.
Yes, it would be nice to export the timeline but that data, admittedly limited to a 1-hour sample rate, is available in the export. “5300W for 5 minutes” should clock as 5300/12 = 442W in the “Average per hour” column.
I went and looked at historical data on Weather Underground and the days it came on corresponds with nights that it got down to < ~35 degrees. I think it’s a heating element of some kind. I admit I have no idea how my AC provides heat to the home. When I look in the Nexia app in the runtime history tab (which unfortunately only goes back 1 week) I see heat, stage 2 heat, Aux heat, Stage 2 Aux Heat, and Stage 3 Aux heat. This is all for the 22nd, which is the last time Sense saw this device turn on.
EDIT: I managed to find a manual for my air handler and found this.
I have no idea what model heater I have. From what I can tell… this only kicks in if it gets really cold. I think my system uses a heat pump until it drops down to the mid 30s.
Could be the heat strips (auxiliary heat) in the air handler kicking in. If you have a Nexia enabled system I believe you can look to see when your system runs and what’s running.
I can… sorta. If I go to the web I can export a months worth of data events, but it doesn’t tell me the type of heat. It just says “Set to heating”. I’m going to post an update soon that shows the data from Nexia and the data for Sense.
I’m working on splitting it up some, but here is the mains PM, and here is the data from Nexia/Sense. The 22nd was recent enough that it was really easy to scroll down through the timeline to find it. I think, but not have confirmed yet, that when Sense says “Device X was on for 5 minutes at 2:25” that means it turned off at 2:25 and would have turned on at 2:20.
Maybe it’s the defrost cycle running on the unit. If it’s cold enough to frost up the outside coils it will run. That will cause the heat strips inside to come on.
Seems reasonably likely you have the BAYEVAC05 @ 4.8kW heater kicking in on top of the other usage at the time and Sense has mistaken it for a water heater.
Unlikely but not impossible that your actual water heater is kicking on periodically overnight on very cold nights to keep up to temp and confusing the issue.
Interesting to consider that the water heater at 4.5kW is close to the heater at 4.8kW … this mains waveform is a good argument for needing something like Sense’s AI to determine whats-what when people argue “But I can see it in the waveform!”. Sometimes, often, it’s not so obvious.
It looks like Sense detected the water heater coming on twice. The times do not correspond with any of the times that Sense saw “Water Heater 2” come on.
Alright, I’ve used Paint to split up what Nexia reported, and what Sense reported for the two water heater devices. Green = Nexia, Blue = “Water Heater 2”, and Magenta = Water Heater.
To see the time periods that the numbers correspond with easier, look at the Google Sheet.
My two cents - The heat strip in your air handler has a similar signature to your water heater. The magenta is the water heater and the blue is the heat strip.
The next time a cold snap comes down there, turn the breaker off on your water heater for the night.
Perfect timing. It got down to about 34 degree at 6am. Before I went to bed last night, I turned the breaker for the water heater off. The first 4 big spikes are the Auxiliary Heat (formally known as water heater 2). The 5th big spike is me turning the water heater back on before leaving for work this morning.
As a side note, I was really surprised how quickly the water in my tank became not hot. I went to bed around 12:30am and woke up around 6:30am. The water coming out of the hot tap was barely warm 6 hours later. The water heater is in a closet in the middle of the house, so even though the house wasn’t exactly warm, it shouldn’t have gotten below about 68. A new water heater is on my list for the next house upgrade sometime in the next year.
How big is the tank? You probably have pretty chilly incoming water but still, an unused tank switched off for 6 hours shouldn’t drop that much in temp unless perhaps it’s recirculating constantly and losing heat in uninsulated pipes along with a poorly insulated tank.
We’re still a little OT, so if you start exploring that maybe poke around existing more relevant topics or start a new one.
