Daikin Altherma 3 monitoring

We had a Daikin Altherma 3 EDLA09DA3V3 installed by Octopus in June this year. Now that the weather has turned colder I’m looking to monitor and optimise the performance.

But I appear to have hit a problem right at the beginning - the energy usage on the MMI and ONECTA app are basically zero, even though there is plausible heat energy produced.

Has anyone seen this problem before and know how to fix it? Octopus haven’t replied and Daikin’s suggestion to “reset the energy readings” was not effective.


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Welcome @squarepeg77 - another Octopus :octopus: Daikin friend. There are a few of us now haha :stuck_out_tongue_closed_eyes:

I’ve not seen that before, but in all honesty, for monitoring, the data is not that great as reported there as it’s rounded (up/down?) to the nearest kWh. It’s useful to track as a baseline and a data verification source however.

Obviously get Octopus to sort it out, but you’ll really want a CT clamp and some sort of monitoring device to get the electrical input power data.

I personally use a CT clamp that is connected to our myenergi EV charger which reports the data in every 10seconds to Home Assistant, then from there to Emoncms. Others here will have other suggestions I’m sure.

I have an Eddi and Zappi, so could add another CT clamp to monitor the heat pump, but I don’t think I can access the live or neutral cables going to it.

The electrician was looking for space to add another mini consumer unit to connect the heat pump to, when I suggested he might use one of the many spare slots on a recently upgraded consumer unit. He did that, but of course now I don’t have a separate feed to the heat pump. Doh. The cable for the heat pump comes out of the consumer unit in a large, tough black cable.

There is another consumer unit outside, next to the heat pump. I don’t know if it is possible to add a CT clamp there, and use a Harvi to transmit the data.

EDIT: For clarity my CT clamp was connected inside the consumer unit by the electrician

Thats what you’re after (this is how mine is setup) - perfect as that will cover all 3 areas (without a breakdown/split) to the sub-consumer unit (you’ll need an electrician to open up the consumer unit at put the CT clamp on)

  1. Heat Pump main outside unit on a separate breaker
  2. Booster Heater (bottom immersion for tank and shuuld only be used for weeky Liegionairre cycle)) on a separate breaker
  3. Backup Heater aka BUH (most likely can be left off on sub-consumer unit and installer settings) can be used fow very cold temps (configurable) and/or for backup heating - this is physically within the outside unit to be clear, but on a separate breaker

This is the 2nd place you can connect to (you’ll need an electrician to open up the consumer unit at put the CT clamp on), and would allow you to have up to 3 CT clamps split accross the 3 points above, and use a Harvi for remote connection

The CT clamp has to clip onto either a live or neutral cable, but not both. (Unless I’ve really missed something!)

Are you suggesting I cut through the black outer shield to reveal the live and neutral and attach CT clamp to one of them? Or some other way of just getting to a single cable?

No! Sorry, I was mistaken (i’ll edit my ealier post), I’ve just checked my setup again, and the connection is inside the consumer unit.

And adding a CT clamp inside a consumer unit is considered a job for an electrician…?

I would have thought so, but am not an electrician, I do not know the regulations for electrics to that detail, nor going to advise anyone who isn’t to open it themselves.

If you know what you’re doing, and are safe (i.e. isolate prior to the consumer unit), then thats your call, hope that makes sense?

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Thanks and understood. I appreciate your help on this topic.

We’ll have a think and a chat with the electrician who installed the consumer unit.

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No you don’t. But you need to understand and know what is live and what isn’t inside, when various switches/circuit breakers are in various positions. I always test with a neon screwdriver (test the screwdriver first on a known live-to-line terminal) that a busbar or circuit breaker I know should be safe really is safe. And beware mistakes and omissions by previous installers!

In essence, the incoming side of the main switch is always live. Everything below the line of circuit breakers is live when the main switch is on. Everything above the line of circuit breakers (i.e. the outgoing side) is live when the c.b. is down (on). But if somebody has broken the rules and convention in the past, all bets are off and treat everything as live until proven otherwise.

Only a few weeks ago I installed a new circuit in a relative’s house. The busbar inside the C.U. extended beyond the installed line of (in this case) RCBOs and two tangs on which to mount two more MCBs or RCBOs were exposed. They should have had a protective boot on.

If you are installing a c.t. (and a c.t. isn’t a “clamp”), then you ought to segregate the low voltage cable from the mains wiring, say by additional sleeving - but space might not allow this. The present regs also require cables exiting the C.U. to be glanded to prevent the spread of fire, should a screw be loose and result in overheating.

If space is short, a ring-core c.t. will be significantly smaller than a split-core one, but it will need the line conductor (brown) pulling out of the breaker’s outgoing terminal to thread the wire through. Be sure to tighten the screw onto the copper and not the insulation when replacing, and that the screw is adequately tight. The data sheet for the 32 A RCBO I fitted actually specifies a torque: 2 Nm for the input terminal (onto the busbar) and 1.2 Nm for the output terminal (for 16 mm² flexible), and it’s the same for a 6 A rating.


Hi @Robert.Wall, thanks for the detailed advice and sharing your experience.

I took the necessary precautions and removed the cover from the consumer unit. I think the easiest option is to fit a CT to the neutral cable for the heat pump. It was the most recently added device and as it is the last in the sequence there is plenty of space.

Regarding the consumer unit knockouts and cable grommets / glands, I think I need to make a new exit for the CT cable (only). Are you able to advise if one of these would meet regulations?

I have a Fusebox, metal consumer unit and the knockout I plan to use is 20mm.

Thank you for any further advice.

Yes, those are suitable. The web page you linked to says it all:
“These membrane grommets are flame-retardant, maintaining the integrity of consumer units and complying with 17th Edition Amendment 3.”

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