Furnace on during AC?

With it being high 80’s here, we finally turned on the central air for the season. That helped me determine that a mystery device Sense had labeled Pump is actually not a pump, but part of the AC. I’m not sure sense has reliably found the fan, but I’m working on that. What is puzzling is why sense though the furnace turned on for 31 minutes yesterday. This looks like it could be the blower, and if so, I’ll name it accordingly. I’ve been trying to think about the various components of forced air conditioning, and so far came up with:

Am I missing anything? Our compressor is a beast, so Sense found that quickly. I’m not sure it’s reliably found the other components yet.

Anyways, here’s my air conditioning furnace screenshot.

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Worth reading this.

It is possible a blower/fan motor. I was able to put my furnace/AC unit on a smart plug and found out that running the fan by itself is 210 watt. When the AC unit kicks in the wattage is 675 for the blower part.


What type of HVAC system do you have? The newer high efficacy “modulating” heat pump systems are very difficult for Sense to identify…

I have a Rheem plus series natural gas furnace and a Bryant AC unit. When the AC kicks in Sense will tell me that the water heater turned on. Both the water heater and the AC condenser are 240 volt. Everything else in the furnace is 120 volt. An interesting observation is that my thermostat uses 8 watt and is always on.

I think this is what I’m seeing. I have started turning on and off the fan manually to try and train sense what the blower alone is, but so far no luck. The wattage I get for the blower is significantly higher than I’d expect a blower to be. Either way, I willing to chalk it up to that.

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I see a spike of 609 watts when the blower turns on, and 413 watts when the blower turns off. Hopefully my “training” gets it noticed by sense.