@cathoderay I hope you are right, however, if so than the panel is reporting incorrectly and not the panel reader.  I have checked several times to be sure I am accurately reporting what the panel says. I just went upstairs and checked again the panel records as follows:

Consumed electrical energy in total (month-to-date) - 15kWh

Delivered heat energy in total (month-to-date) - 5kWh

I know I'm simple minded but it seems to me something is just not right here. In 24 hours from 08:00 on 05 Sep to 07:30 on the 06 Sep the system according to the panel consumed 3kWh of electricity (rounded, I assume to the nearest whole unit). The heat pump ran during the night and consummed approximately 1.75kWh (according to the solar inverter). And yet the panel says the heat produced was 0kWh so I assume it is something less than 0.5kWh. Which makes for a COP of less than. 0.29!

I intend to raise this with the installers but just wondered if anyone no the forum had any ideasbefore I do.

@minos - do you have access to historical data and charts on your controller/app or whatever you have? If so, you can look at the data and perhaps see what is going on? I also think I am right in saying you also have solar and that or a CT clamp meter spooked your main kWh meter readings. Could it also have spooked the heat pump (even after the CT clamp error was corrected)? Maybe turn the whole thing off wait half an hour or so, and restart it, ie cold reboot it? 

@minos once again the existing regulations will come to your aid.

You don't say whether the Ecodan ASHP was installed by the same MCS-accredited company as the one who provided you with the Solax inverter and battery combination.

However, your Heat Pump must be installed so as to comply with Building Regulations Part-P (electricals) and Part-L (conservation of fuel and power).

It's extremely unusual for a heat pump to not satisfy the requirements of Part-P.
Electricians are members of accreditation bodies who can inspect work and enforce the standards.

Contrarywise, Part-L is rarely satisfied by installers.
There are no checks. The installer merely sends a Notification to the Building Control Dept of your Local Planning Authority.
This is called a self-certification under the Competent Persons scheme.

Here is the relevant section of Part-L regarding Commissioning:

Note that it must be adjusted to consume minimum power.
Simply running it up and testing for leaks isn't commissioning!

And here's the relevant wording in the section about hand-over and training of the end-user:

@minos I would give octopus a nudge on Twitter (sole reason I have it!) or a call. I’ve found them very responsive that way and you’ll likely get a slot for a few weeks time. The register your interest forms tend not not yield results as quickly.

I’m no expert but your issue sounds like a faulty/incorrectly fitted sensor?

Posted by: @minos

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@toodles I think the meter is not changing because I am not drawing any power from the grid.  The panels are producing more than enough for my current needs. I suppose I could make an issue of it with the installers but it hardly seems worth it for the relatively small sum of money involved.  I'm just glad I kept an eye on it and had the courage to raise it with the installers after only a few days and not after a month or so.

Which brings me to the question I really wanted to ask and that brought me to the forum in the first place.  Since installation the ASHP has been used only for DHW. The hot water storage temperature is set to 50°with an allowed  drop of 10°. Every couple of days the water temp drops to 40° and the heat pump uses about 1.75kWh to raise it back to 50°.  Every two weeks a legionnaires cycle runs, this has happen only once since installation. The Ecodan panel reports the following:

Aug Elec. consumption 37kWh, heat delivered 19kWh

Sep so far consumption 15kWh, heat delivered 5kWh.

If I understand correctly this makes for a COP in Aug of approx. 0.5 and in Sep approx. 0.3.  Can this possibly be correct or am I failing to understand what is going on?

Also am I getting carried away and posting this question to the wrong section of the forum?  Tell me if I am.  I never expected such rapid responses to my initial post.

@minos,

You won't get anything like accurate figures with such low usage unless you have external power (consumed) and heat (delivered) meters.  The internal Ecodan metering just won't do it; it is a well known 'feature'.  Just ignore the numbers until you start using it a bit more. 

The other point to note is that most Ecodans seem to use about 24 Watts just to be on standby. That would account for about 17kWh (24x24x30) per month.  That goes almost unnoticed in the winter when you're using hundreds of kWh per month. But when you're using as little as you are at the moment, it really distorts the COP calculation.

@kev-m Many thanks Kev. I can accept this.  I just wanted some reassurance that this wasn't something I should be pursuing with the installers. Appreciate you taking the time to explain.

@minos Hi - just to back up Kev's points, I had similar questions about our Ecodan R32 ASHP when we first switched off the heating and were only running with DHW.

I ran a test to measure the true standby load for our complete Ecodan system, and confirmed it was 20-21W including the FTC controller (measured at 16degC).

Yesterday the ASHP ran for 15 minutes on DHW, and DHW consumed energy was recorded on Melcloud as 0.2kW.  Heating consumed energy recorded on Melcloud was 2.6kW!!

@skd Thanks

Interesting that your heat pump ran for only 15min. Was that a 10° lift in water temp? Mine ran for approx. 45min!

Posted by: @minos

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@skd Thanks

Interesting that your heat pump ran for only 15min. Was that a 10° lift in water temp? Mine ran for approx. 45min!

The rest of DHW demand that day was met by the immersion as it ran a legionella cycle and didn't need to call on the heat pump.  Our normal DHW days would involve more heat pump duty.

Hello everyone. I live in North Wales. I built a timber frame dormer bungalow using Kingspan/Potton back in 2015.

I wanted it to be an Eco house. We have ground source heating, Solar water panels, Rainwater harvesting, 7 pv panels on a shed roof. This year we have added another 12 pv panels which are frame mounted in the garden and have been virtually off grid since April. We also have 2 x 9.5 kw Giv energy batteries. We will have to see how we get on this winter with the set up.

It has been worth doing and we have found it to be very comfortable living in this house.

Hi @andy-offgrid

Potton homes are known to me from visits to Homebuilding Shows over the years. That's a good basis to start from.

Your location in North Wales would suggest to me that you might be able to deploy a micro hydro-turbine, which would produce reliable output in the winter months.
Or have you coincidentally founded the house on the 1% of flat land in the country?

Hello Transparent, I am on top of Halkyn mountain! Yes everything is on a slope. We are considering a turbine, but need to research it. We have neighbours close by.