0 Watt waterheater?

I’ve got a heat pump water heater that is 240v (L1, L2, G) so I have a CT on one of the legs and Double in the input selection. It spikes up once or twice a day on demand times but otherwise it’s sitting at 0 watts. This seems almost impossible given it’s got a little display and a couple of LED’s. Is it just that the steady state draw is that low? ie, a fraction thus rounding down to 0? Part of me has a little concern b/c this sits on a generator ATS panel which hangs off of one of two 200amp panels in a 400amp split fed service.

Configuration: 400amp feed to meter, splits to two 200amp panels. Panel1 has the voltage reference. Panel 2 feeds the generator panel which is where the water heater sits.

A conventional water heater does go to zero as the controls are just switches. I don’t have a heatpump unit but have looked at a few. They do have controls and led lights, but that can (and should) be very low power. IoTaWatt won’t report 1 Watt. It has to be 2 before it takes a load seriously.

My water heater circuit also has controls and a pump for solar thermal. Like several of my circuits I have a revenue grade EKM meter on it to compare to IoTaWatt. They don’t agree. The EKM has a start threshold below which it won’t record. The EKM is 5(100)A and has a base current or Ib of 5. It starts at 0.4% Ib, which is .004 X 5 or .02mA. .02mA x 240V = 4.8 Watts. So it won’t even bother with anything less than about 4.8 Watts. I scratched my head for awhile because IoTaWatt was showing more energy than the meter, until I realized the meter wasn’t running while the controls for the solar were the only load. Sadly the controls are old school and use a 24V transformer that uses a few watts.

The point is that when you get down to very low power, even the better revenue grade meters have issues. They get around it by not recording low power. IoTaWatt does the same, but with a little lower threshold since it doesn’t need to pass revenue certification.

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For comparison, my heatpump has a small 12v transformer in it running the external thermostat.

It sits at 0w measured unless its actively moving heat.

Fascinating replies. Thank you both. I was just nervous given the chain of panels.

Something of note here, my pool pump will go down to zero too, while the controller is on and has a little screen. Since its just on 12 awg wire, I looped the second through the CT, and sure enough, consistent 3w

Even though it only has 2 hots and a ground, I think its being sneaky and putting some current down the ground to get 120v for the controller

A pool pump should be on a GFCI and I think it would trip if that were the case. More likely you are just doubling the Amps and now it’s above the 2 Watt threshold.