Newbie starting with monitoring power & heatpump, need some hints please

Hi Guys,

I’m so pleased to find your org, I’m completely in the dark about my power consumption and heatpump behaviour and your solutions look like they will help enormously, so thanks up front for just being there!

I have 2 heatpumps, several immersions, a huge electricity bill, and quite poor data from the heat pump controller (ok virtually none), and NO smart connectivity from the controller to anything (Nu-Heat say it won’t ever talk to anything).

I’m seeing two phases to my needs, partially because of my knowledge gaps & fear of the unknown.

  1. Just power monitoring, probably at least 4 inputs, possibly more.
  2. It’s heat pumps so I ought to be thinking about the heatpump monitoring (except my lack of understanding of it & how to monitor it).

Stage 1 looks quite straightforward, as long as I can find the power input wires on the relevant boxes, (getting advice from Nu-Heat about that, so optimistic). So that looks relatively straightforward & I’m looking forward to that. (Local database not cloud!).
Stage 2 is less clear to me. I could do with some pointers to documents on what to monitor, and how. I don’t believe the Grunfoss circulation pumps will provide any data, so how can I find the pressure drop (is that necessary?). The Hitachi heat pumps seem to have a display which (if you hit the little “i” button will scroll through Temperatures out & return etc) but no visible interface port.
I’m a bit lost with the concepts really, so would really appreciate some nudges in the right direction. Assuming the project is still live.

I’m an old techie so building the kit & doing a bit of soldering is not an area of worry! I have networking everywhere (wireless and wired), I’ve also built dozens of raspberry pi projects, so that holds no fear. It’s just the interface to the heat pump which I’m in the dark about.

Ooh - and I would be very interested in noting any temperature loss between the heatpumps & the house manifolds, if that’s poss. The heat pumps are in the garage.

Hope to hear from you in the fullness of time, there’s no hurry I have a lot on my plate currently, so it’s a new year project.

Thanks in advance

Hello Lee

You might be interested in our development project to monitor heat pumps here and its worth reading @johncantor’s post on heatpump monitoring here:

I have found it really useful having the heat meter measurement for my own heat pump, a heat meter measures flow and return temperatures as well as flow rate. We have worked with Kamstrup 402/403 and Sontex Multical 531 MBUS heat meters. Installation is tricky as it requires system drain down (assuming your system is heating water?), a job for a plumber. Good heat meters are also unfortunately quite expensive.

A heat output measurement together with electrical power input measurement gives you the heatpump COP which effectively tells you how well its working, how many units of heat output you get for each unit of electrical input.

You can still gain a lot from measuring system temperatures and power input only. Its possible to get an approximation of the COP using the carnot COP equation Learn | OpenEnergyMonitor and at least keep an eye on system temperature (the lower the flow temperature the better) and cycling.

Hi Trystan,

Ooh that does sound interesting, thanks for the response.

I’m already learning about my system, such as the fact that it does NOT heat my water, which is a huge surprise, and possibly a contributory reason for my high bills.

I think as I learn a bit at a time, I will be able to ask more questions, so that article is a godsend, thanks.

Eventually, once I think I know enough, I’ll be brave enough to go with the monitor system. I really REALLY want to know the COP, because all I have to go on currently is a huge elevtricity bill & some sales blurb promising a COP with no way to prove or disprove it.

Thanks you’ve given me some inspiration to get to the next step, so thanks that’s much appreciated.

All the best


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