OpenEnergyMonitor Community

Heat pump monitoring introductory video thanks to John Cantor

@johncantor who we have been working with on heat pump monitoring for quite a few years now has posted a nice introductory video on monitoring heat pumps with an emonTx or emonPi.

He gives a good example of what you can do with simple electricity and system temperature monitoring in a way that’s relatively easy to retrofit onto an existing heat pump system (compared to installing heat meters etc)

John has also been doing a range of other video’s on other interesting heat pump related topics such this one on a simple heating simulator tool that he has put together:
Heating Simulator John Cantor - YouTube

another on pressure drops and flow rates:
Flow-rate and pressure-drop simulator - YouTube

heating old buildings with heat pumps:
heating old buildings with heat pumps - YouTube

heat pumps and the potential harm due to refrigerants
Heat pumps and the potential harm due to refrigerants - YouTube

If you find any of these useful, Im sure John would appreciate a comment or other sign of appreciation on his youtube pages. I know he has put a lot of work into these and has a wealth of knowledge on the subject that he’s always been very happy to share.


I’ve been thinking of getting John’s book: Heat Pumps for the Home : 2nd Edition: John Cantor: 9781785007798:


It’s a great book, a really good introduction to heat pumps and the different installation options, explained in an accessible way with nice diagrams! :slight_smile:


A good series of videos from John there! The pipe sizing one caught my interest, as I have seen countless times, poorly sized pipe runs on installations resulting in poor flow. I don’t think it gets the attention it deserves by many installers.

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Very inspiring from Mr Cantor :sunglasses:
So much, I went out and changed my Temp sensors on my Sanden Hot Water Heater around and ‘attached’ them to water inlet and outlet, and added a Power Monitor (Shelly 1PM) to the circuit.

Now I ‘see’ this view:

I guess to do temperature monitoring properly, the sensors would need to be specially inserted in the pipe somehow for accurate measurement of the water. My ‘poor mans’ method involved putting temp sensors against the copper pipe tucked in between the pipe insulation.

How do others do this ?

Great @muzza, John wrote a good blog on attaching temperature sensors here:

Although it’s nice to have them in pockets for the most accurate results, attaching them to copper pipe with a couple of cable ties, thermal paste and a lot of surrounding insulation seems to work fine as well. I used this approach when attaching a monitor to diagnose an issue with a system the other day.

From John’s post in the Strapping a sensor to a pipe section:


Thanks for the question @miker and the recommendation @TrystanLea - I had wondered about getting this book when I came across it in my online searches a few weeks ago. Now ordered.

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Thanks @TrystanLea and @johncantor for the links and pictures of strapping sensor probes to copper pipes. I modified my initial quick fix attempts and made them a bit more professional! The two sensors now look very similar to the pictures supplied. I am now getting much more accurate temps from the input and output temps to the heat pump while it is running.
So thought I would look into the MyHeatpump App. Had to update the App Component on my system first. The resulting display is as follows:

The Flow and Return sensors are under insulated pipes but from 09:30 the heat pump and pipes are in full sun so that’s why they increase leading up to 11:00am startup time.
Once the unit is running the return temp falls to the temp of the water at the bottom of the 300l storage cylinder. The flow temp remains just over 60 for the duration. As the bottom water temp increases it reaches 47c and the unit switches OFF for the day.
I added an outside temp entity,(purple line) but it is not entirely accurate because it is not close to the heat pump hardware… (yet!)
Anyway, just a bit of feedback for you. Cheers

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Very good information.
What kind of sensor are you using to measure the flow?

Im only measuring three things for the heat pump.

  • Temperature of the water just as it enters the heat pump (Return / Green line)
  • Temperature of the water just as it exits the heat pump (Flow / Red line)
  • Power (watts) of the heat pump (Electric Input / Blue line)

I also added an Outside air temperature measure (Purple line) but this is only approximate as the sensor is not really near heat pump.

The My Heatpump app in my local EmonCMS is configured like this:

I don’t have any hardware to measure actual ‘heat’ output. As I understand, if I did, the app would display a more detailed performance indicator (COP). I tried this app out to see what a simulated calculation would look like.
I checked the option ‘Simulate heat output using Carnot COP equation’ under the Show Detail section at the bottom of the graph.
I have not yet delved into the details of the equation. So far it has been an interesting learning experiment. :sunglasses:


Great to see @muzza! Do you have temperature sensors in the water tank by any chance? Can you work out from the tank water temperature rise an estimate for heat input and compare with the heat calculation using the above simulator? Does 5.4 kWh of heat gain in the tank sound about right?

Yes @TrystanLea that’s probably my next step. More tinkering, more learning, keeps me occupied.

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