Getting Started with Grant Aerona 3 and Junction Box Monitoring

Hi folks!

I want to monitor my Grant Aerona 3 as well as our single phase main junction box. Before I start buying equipment I want to ask this community what components I need to organise if thats ok?

Why am I doing this?
I live in Ireland. We were lucky enough to be able to be able to move into a brand new home just over 2 years ago. The home is A-rated, and comes with wet underfloor heating downstairs, and low pressure radiators upstairs. The home is a detached property, with a footprint of around 2,300 sqft. We have no solar panels or tubes.

Each year I have made sure we are on the lowest energy rates from the selection of national energy suppliers. But still, I remain really surprised at our electricity costs. Having moved from heat-leaking, draft filled homes, I’m paying the highest electricity costs to date. If I use my most recent bill as an example, covering usage from 05/05/2020 through to 01/09/2020, a relatively low electricity consumption period. Our electricity bill for the two months was €487 (representing 24 kWh usage in that period).

I appreciate costs are driven by many variables. But these costs keep niggling away at me, and I feel that we’ve never really ruled out a problem with the installation. My hope is that I will be able to identify where I am drawing power in the house, and to narrow down if I have a problem, or not. I’m hoping this community (or a professional) can work with me on the data to understand if the ASHP is running well or badly (given it is likely the biggest energy consumer).

So what am I looking to monitor?

  1. I want to connect into the ASHP, a Grant Aerona 3.
  2. I have a number of electrical circuits on the main junction box I want to monitor, the ones I’m thinking of are:
    1. The main 80amp breaker for overall house energy consumption
    1. The 20amp breaker for sockets in our attic (I have low energy computer equipment in the attic and I want to know how much that is contributing to it).
    1. The 60 amp breaker for the ASHP
    1. The breaker for the immersion (rating TBC)
    1. The breaker for the cooker

Hopefully this all makes sense. I don’t want to be soldering anything, is there a configuration which covers the list above?

Kind regards,

Welcome, Chris, to OEM.

Not in one unit, I’m afraid. I assume you have a UK standard single phase mains supply? It seems likely as you mention an 80 A main breaker.

I think you’ll need an emonPi to monitor two circuits and provide the data processing and recording facility, and to that you’ll need to add an emonTx - giving you 4 additional circuits.

I’d guess the immersion heater is 3 kW maximum - say 12 A on a 20 A breaker, and the cooker is likely to be a 32 A breaker.

So I think your shopping list is:
1 - emonPi
1 - emonTx
5 - 100 A c.t.
2 - a.c. adapter
1 - 5 V USB power supply.

The big question is, is there room in your consumer unit/distribution board to get all those c.t’s in, or can you access a single cable (not multicore / flat twin) to put the c.t’s on - within a metre or so of the C.U?

Morning @Robert.Wall,

Thanks very much for the help. Am I right in saying the shopping list gives me energy reporting, but not the ASHP monitoring?

I’m not a heat pump engineer, so I know I would struggle to interpret the data coming from this module. But I thought it would give me data points which I could use to ask for help. For example, I thought the real power draw happens if the compressor fires, rather than just the heat pump cycling. At the same time, I appreciate I don’t even know if I have an MBus or VFS flow sensor on the Grant heat pumps. Can anyone here confirm?

Re: the CU. I have enough space for all of these clamps. The electrician I worked with was great and I’ve space for expansion, and by extension of that, I have space in the CU for these clamps. I’m currently using two clamps connected to zwave Aeotec energy monitors. They’re not reporting correctly and I plan on replacing them with this project.

Kind regards,

That’s correct - it will report the energy consumed by the heat pump, which is what I thought your primary concern was (your point 3). It won’t monitor the thermal output of the heat pump. For that, you need to add (or maybe substitute for the emonTx) the Heat Pump Monitor I know next to nothing about that, so we need to consult John Cantor or @glyn.hudson or @TrystanLea to see if there’s spare capacity in the heat pump monitor to monitor its own plus two additional circuits, or whether you still need the emonTx.