Monitoring state concurrently with Power

Case Studies
1

Hi everyone,

I’m new to IotaWatt and have my first install up and running. So far it’s working great.

I’m interested in monitoring thermostat states concurrently while monitoring energy consumption from a geothermal heat pump.

The Geo is my biggest energy consumer and it services 5 different zones, each of which can call for heat or cooling. What I’d like to do it monitor each of the individual thermostat status at the same time I’m tracking power consumption of the Geo with IoTaWatt. This way, I could approximate the energy cost per zone. For example, if zone 1 was the only zone calling for heat in a particular time period - I could allocate 100% of the energy consumption to that individual zone. If zones 1 & 2 were calling at the same time, I want to allocate energy use per zone based on zone size. The zone sizing is pretty simple and could be divided easily even if the zones are not equal. For example, a 1-ton zone calling for heat at the same time a 2-ton zone would be divided 1/3 and 2/3 respectively.

Anyone have any ideas on how to accomplish this? My first thought is to find/build circuitry that monitors the thermostat zone states and logs data to the same place the iotawatt does.

Another thought I had was to duplicate the energy monitoring of the Geo’s mains 5 times and run an output function that factors in the zone size. This would approximate the zone’s energy consumption if it was on. Then combine the data with something else that was monitoring the zones true on/off state.

David

2

Welcome to IoTaWatt.

You would probably need to go to an external database like influxDB or Emoncms to log the thermostat state. Both are capable of logging on/off state. With influx, you would probably need to build something. I think the Emontx can handle on/off sensing and has the ability to send that to Emoncms via an ESP8266 or a Rpi.

If you are just interested in a proof of concept rather than an ongoing reporting system, then I would suggest using something like a HoBo datalogger to record the states, and then match that data with the Geo consumption in a spreadsheet. If you get what looks like a useful analysis, you can go the next step.

In a past life I did some heating system designs. Don’t know if you have forced air or FHW/radiant but either way, the flow rate of the transfer fluid and temperature differential is the best way to apportion the gross energy. My approach would be to just do a heat loss (gain) calculation on the envelope by zone and break it up according to those ratios. I’m thinking that would be pretty good if everything is more-or-less steady state.