I am using a Shelly EM to monitor usage of my central air. On the panel side, I have two 30 amp breakers for AC. Right now, I have 1 Shelly EM with two clams, 1 going to one wire on each breaker. This works fine, but is really only showing me about half my usage because I’m not monitoring both legs of each breaker.
I had hoped to create a template sensor that would double what I am reading from the EM and provide that value to the Energy dashboard but when I try to add a device within the energy dashboard, my double value isn’t an option to select.
Anyone have a way around this without buying another EM and 2 more clamps?
template:
- sensor:
- name: "Double AC Air Handler"
unit_of_measurement: "W"
device_class: power
state: >-
{{states('sensor.shelly_shem_c45bbe796718_1_current_consumption') | int + states('sensor.shelly_shem_c45bbe796718_1_current_consumption') | int }}
- sensor:
- name: "Double AC Unit"
unit_of_measurement: "W"
device_class: power
state: >-
{{states('sensor.shelly_shem_c45bbe796718_2_current_consumption') | int + states('sensor.shelly_shem_c45bbe796718_2_current_consumption') | int }}
They are power sensors. The energy dashboard only accepts energy sensors.
The energy sensors must have a state class, most likely total_increasing.
Also you should add an availability template to your energy template sensor to prevent pollution of the statistics when your sensor children sensors are unavailable.
Also, also FYI, to double a sensor value you can just do this:
If so then one wire for each breaker should measure the total current flow for each circuit.
on a 120v breaker all current goes thru the breaker leg and returns on the neutral leg (alternating of course).
on a 220v breaker all current goes thru both breaker legs in series (all current goes out of one breaker leg and returns to the other breaker leg). there is no neutral. Only a ground.
There are some systems that use a neutral to provide some 120v control voltage stuff so it is possible yours does but the 120v current will be minimal compared to the 220v load.
If you aren’t in the US then I’m not sure how things are wired so disregard the above.
Yes, in the US. Only monitoring the 220 breakers for my central air right now. With a single CT on one leg of the 220 breaker, that would only measure half the current, unless I am wrong on that.
If you have a shelly with 2 CT, why are you only using one? As @finity said, if you use both (careful to orient them properly as you could end up with one of them giving you a negative reading if both oriented in the same ‘direction’) you can read the full current used by your AC. I have an Aeotec Home Energy Meter in my main panel with a CT on each legs and can read full home power usage.
Each leg on a 220 breaker is going to have the same draw of power. Why use a CT to measure something I already know the value of, because I am measuring 1 side already, when I can instead monitor another circuit with the other CT?
Ah, true. My 2 HVACs are connected like yours but since the loads on the sub panel are not equal on the 2 hots, I measure current on both. I don’t get a unique reading for the HVAC but I can just monitor the delta to get an idea. I also found that the blower and control board are not powered by the 240V connection that powers the outdoor compressor and in my case the power draw of the blower and control board is another 600W.