Dedicated Circuit Monitoring for heat pump in the main panel?

Technical Questions
#1

I have new heat pump system for all of my heating & cooling, and after 3 months or so with Sense, it hasn’t been found. I bought the flex sensors so I could monitor the heat pump’s power usage, since that’s one of my larger loads. Also, I’m about to do some insulation work in the attic and thought it might be interesting to see the usage difference. The heat pump is running off a 40A breaker in my main panel, which is monitored by sense.

Is this the correct use case for the flex sensors? I’ve noticed that my “other” bubble seems bigger than it was before the installation, and after reading some other posts I’m not sure they are supposed to be used this way. (In particular, is the main sense unit able to remove the dedicated circuit data from the main sensors?)

#2

This would be a potentially suitable utilization for Flex Sensors - to confirm that, we’d need to see some photos of the inside of your panel. I just adjusted your Community permissions so you should be able to submit photos here as well.

In case you haven’t already seen it, the Dedicated Circuit Monitoring installation guide is located here and contains some more specifics on installations and how they vary by the type of circuit you’re monitoring.

#3

Thanks Justin, here you go. I did read the guide, and found it helpful. I think it could use a diagram or two though.

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#4

Hey @sethrh - everything looks good with your installation. I’m wondering if you’ve completed the in-app set-up yet?

To set-up Dedicated Circuit Monitoring in-app, navigate to 'Settings > My Home > Connected Devices > Dedicated Circuit Monitoring’ and follow the in-app set-up flow. To complete the set-up, you must also include the ‘What’s being monitored?’ field to let Sense know if you’re monitoring something it detected natively.

If you’ve done both of these steps already and still aren’t seeing the Dedicated Circuit device in your Sense app, please write into support@sense.com so they can take a deeper look.

#5

This looks like a 240V-only load (no neutral connection). You don’t need to use both flex CTs on such a load. I’d recommend getting the most out of your flex CTs by using the other one to monitor a different load, which could be 120v or 240v.

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#6

I did yes, I should’ve mentioned that. The sense does show the DCM load as its own bubble. What I was noticing is that after doing that (and getting the bubble) my “other” bubble seemed to get unexpectedly bigger. When I started scratching my head on that, I looked around here and wasn’t sure if this is how the sensors are supposed to be used.

However, as @pswired suggests, can I use just one clamp to monitor this (I’m assuming I’d need to clamp both hot wires on the 240V breaker in the same clamp)?

I’d love to have another clamp free to throw on a spare circuit, there are a few other loads that I have that sense isn’t finding entirely.

Does sense learn how to detect stuff on the flex clamps, such the clamps could be moved to another circuit after a while?

#7

I’ll look into this/ask some folks around here what could be causing this, but to confirm - your Dedicated Circuit device (heat pump) is currently visible in the ‘Now’ screen as a bubble, but the ‘Other’ bubble seemed to get larger after your set-up DCM?

At this time, you can’t use flex sensors or smart plugs to train Sense to detect devices and neither should impact Sense ability to detect that device in the future.

#8

Is there hope for improved Sense ability to pick up the various components of central whole-house ducted heat pumps? I can see various components of the heat pump in the real-time patterns, but there doesn’t seem to be a way I can give Sense a hint about what it should be looking for. Are you working on how to detect these things - as an alternative to direct monitoring of a circuit?

#9

We’re going to be updating the Community (and our user base in general) with updates we’re planning involving device detection in the next couple of months that applies to a lot of devices that are difficult to identify with real-time detection. You’ll definitely see us sharing more information ahead of this webinar (or Q&A, it’s undecided at this point), so check back in the next month or so.

So while there’s a ton of places we’ve mentioned in the forums re: manually assisted training not being something we’re pursuing right now. That being said, as part of the news I hinted at earlier, I’m hopeful that we’ll be doing a better job of this in the coming year.

#10

Justin,

Thanks for quick response!

In a previous house I tracked kWh use for a heat pump for 6 years (using a separate meter installed by the municipal utility), but I have not been able to come up with comparable kWh numbers for the new heat pump in a new house we’re living in in Acton. Sense has ID’d a device that includes alot of heat pump usage but apparently not the fans that circulate air thru the ducts and possibly other elements. There’s a gas furnace installed together with the heat pump, and Sense only detects the ignition, not the burner itself.

I am working on heat pump promotion and coaching with the HeatSmart Alliance. I’m also working with MassEnergize to set up a site for Acton, and we’re considering promoting Sense as an “Action” – but I can’t see doing that until it can detect the whole heat pump, since we’re working on a promotion of heat pumps as a major focus.

If you have any suggestions for hacks or other approaches to address this problem, let me know. Thanks,

Fran

#11

Yes, I have a new bubble showing my DCM device. The “Other” being bigger is my impression, it seems like it used to be about 700W, now it seems to vary more and be larger, 1200 W. I’m fairly sure that most of the “other” in my case are computers.

I should also be clear that is just an impression - I have a pretty good handle on the loads in my house but if my kid turns on a space heater or something I probably wouldn’t know.

This is what it looks like now, or what I’d call “normal”. Other is currently about 700W like it usually is during the day (computers), always on is 367W (server/networking/TV vamp loads)

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If you use the clamps separately (on different circuits) do you get two DCM bubbles?

Thanks!

#12

Here are the instructions for monitoring two loads with the dedicated circuit CTs:

#13

Yes, as long as you re-do the in-app set-up for dedicated circuit monitoring and select “2 loads” from the set-up, you’ll be able to see each circuit/device separately.

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#14

Perfect, thanks.

Also, I observed what I previously thought was “double counting” again:

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Here the “Other” and “Heat Pump” are almost the same number, and “Other” is really big. Besides the heat pump, the only loads that I have capable of getting close to 5kW are the dryer and stove (neither of which were being used at the time).

I was able to do a rough estimate from the usage graph in sense (the peak from 8-8:30 is about 12 kW, and from 8:30-9 it’s about 2.5 kW which works out to about 7.25 kWh for the 8-9am hour).
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This corresponds very close to what my utility reported for total usage (via my smart meter).
2021-Jan-23

So Sense reported the correct amount of power that was used (it’s not a double counting error). I assume it must be power that the heat pump was using, except that all goes through the one circuit with the attached flex sensors…

… and I just realized what it has to be. There is one other big circuit in my panel - the water heater. But it’s a heat pump water heater and is so efficient that when it can be bothered to turn on it only uses about 250W.

I recently changed it’s schedule so that it’s turned off at night until 8am. It was cold that morning, and the water in the tank must have gotten cold enough that the water heater decided to get a boost from the resistive elements. (I was wondering if it would save power to turn it off at night. I guess the answer to that is “not if the heating elements turn on”).

So yeah, looks like everything’s working as intended. It’s amazing what you can figure out when you have some data to look at!

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