I am wondering if there is a list of materials that I would need to monitor an air to air heat pump. The current bundle on the shop is for air to water heat pumps.
Hello @hunterdartmouth and welcome! We dont have a solution for air2air that accurately measures heat output but you can use the EmonTx4 to measure electric consumption and three temperature sensors, outside temperature, air in and air out of the indoor fan unit. That alongside the datasheet air volume rates through the fan unit could allow you to estimate some ranges for power outputâŚ
Another approach could be to attach a temperature sensor to the metal body of the refrigerant to air heat exchanger in the fan unit to try and get the condensing temperature and then use the carnot equation to estimate COP? E.g: https://docs.openenergymonitor.org/heatpumps/basics.html#carnot-cop-equation
Both approaches will have significant error margins but may be useful enough to see what is happening?
Thanks, I wonder if there is scope with the Emon hardware to add a hot wire air speed sensor, which could measure m/s and then we could do some math on the size on the opening? What do you think?
The indoor units usually have a rated air flow at certain levels, measuring the rotation speed of the fan could be another way to have a continuous data point by finding a way/formula to corelate everything.
Have in mind the air temp sensor that is on top or next to the coil already measures a temp higher than the actual room air temp and makes the machines stop earlier.
Could also be possible to see if there is a correlation between amp draw on the blower motor and air flow. Then one could have a current transducer installed on the blower motor.
All good ideas⌠feels like the challenge is to calibrate the setup somehow? Could be done with a room heat up test vs an electric fan heater perhaps? Measure room temperature accurately with multiple room temperature sensors, power input to the electric fan heater and outside temperature and do alternate heating periods with the a2a and electric fan heater?
Older thread but very interesting. Also have an air to air setup. Also in a balanced heating/cooling climate. (USA)
Are there no in-line refrigerant heat meters? I realize that they would require skilled labor to install (pump refrigerant down, vacuum, flare etc).
Does anyone know what would actually be needed here? Going to be different for centralized ducted blower systems than for mini-splits.
For ducted systems Iâm thinking some airflow and temperature monitoring in the ducts could be useful? Perhaps something could be done with pressure differentials?
For calibration in minisplits perhaps a flow hood over the whole unit could give airflow to power draw for the blower motor mapping?
Another approach that would work for cooling might be to run a resistance heater in a battle with the cooling system. Then, since one knows the output of the space heater, one could know the output of the cooling system for a given power draw? Obviously only useful for calibration, not for live long term monitoring 
Blows my mind that there are not more data available in the boards themselves. For example it would be nice to at least know what different heads in a multi split system are calling for?
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Hello.
I recently installed Daikin 8 kW air-to-air 4 way multi-split system. Through Faikin ( GitHub - revk/ESP32-Faikin: ESP32 based module to control Daikin aircon units ) I get the following in Home Assistant:
- total energy consumption in kWh
- outside unit ambient temperature [T_ambient]
- refrigerant liquid temperature [T_flow]
- fan rpm
- compressor rpm
- near indoor unit temperature (this swings quite a lot depend on liquid refrigerant temp)
- Plus, I have a general room temperature sensor
Are my labels in square bracket correct numbers to use for?
The My Heatpump app in EmonCMS contains a lot of extra feeds that wonât be available for air-con units. Can I leave them empty? For example: heatpump_heat, heatpump_returnT, heatpump_flowrate, and DHW stuff. heatpump_targetT is heat pump target flow temp?
I will be installing an almost-identical air-to-air system in a new building next month, so I will be looking to set up monitoring for that too.
The âMy Heatpumpâ app is very much tailored for air-to-water systems so while you certainly can configure the feeds which âoverlapâ with the data you have available, the benefit of using âMy Heatpumpâ will be limited and it might be more useful to set up an alternative dashboard. For example, âfan rpmâ doesnât have a âhomeâ in âMy Heatpumpâ.
Thatâs generally how people use it, yes - as long as thereâs a feed available which provides a value for that. Alternatively, it can be used to track the target room temperature. The note in âMy Heatpumpâ says: âTarget (Room or Flow) Temperatureâ
Are you getting âtotal energy consumption in kWhâ from the Daikin unit (via the Faikin adaptor) or do you have a separate electricity meter providing that?
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Hopefully I got this calculation correct?
But thinking about it, I donât think refrigerant flow temperature should be used as input if the equation is designed for air-water HP. The water flow temperature in air-water will be lower, it has to go through another heat exchanger to get the heat from refrigerant. For air-air HP, may be the out-flow air temperature should be used?
For a multi-split system, how does one unit affect the other? Is overall COP a time-weighted average across all units?
This comes from Faikin, similar figure can also be found in Onecta for each device split into heating and cooling. I only have whole house energy monitor, didnât get a separate monitor for AC as there was no room inside my consumer unit.
Faikin exposed sensors via MQTT, thereâs others that are disabled, either doesnât apply to me or I donât feel it is needed.
This is via Daikin Onecta custom integration, with a rate limit of 200 per day across one account (hence I got Faikin):
