Welcome to the forums.

I assume that you're getting the MelPump data via the MelCloud integration?  Assuming so, then the daily totals are those being reported by the Ecodan unit itself, and Mitsubishi's reporting tends to overstate energy usage to some extent.  Is there an electricity smart meter within the installation, as the first thing to check would be how closely the usage figures align to the actual consumption?

Having said that, the MelPump data suggests that the unit is cycling quite frequently at an outside air temperature of around 7°C, which will adversely impact efficiency, so there is definitely scope to look to improve how it is running if this is typical.  The COP figures across the 12 month period do also look very low in general, albeit the assumption is that the summer months are showing only performance for Domestic Hot Water, which will naturally be less efficient.  Oddly, your MelPump data doesn't look like its giving the option to show DHW COP and Heating COP separately, which is different to how the graphs display on my system.

Those with more technical expertise than me will likely reply requesting more specifics regarding your system.  The logical start point for performance issues would typically be an oversized system but a 6kW heat pump would suggest a fairly low heat loss.  Do you have any information as to what the assessed heat loss was at installation?

One thing I did spot was that the flat target temp you're showing in the graph is for zone 2, but the actual data is for zone 1.  Is your system set up as a zoned one, or is there a single open loop?  On the current display the target temp needs to be shown for zone 1 so that we can see what the weather comp setting is trying to achieve, rather than the flat profile for (a presumably non-existent) zone 2.

On the detailed report, do you have a 'share as URL' option?  If so, then this would be the most useful way to post the data, as it allows readers to highlight the individual graph points, which may assist their diagnosis.

There are definitely some elements of your post that I can attribute to the inaccuracies of the Mitsubishi reporting, one of which is the fact that the inaccuracies worsen when auto-adaptation is used (see post here regarding this https://renewableheatinghub.co.uk/forums/postid/58460/) which would potentially explain some of the gap between the 1.7 Auto Adaptation figure and the higher one for weather compensation.  However, the overall CoP numbers do look very low in general, so any inaccuracies of reporting are only part of the diagnosis and the frequent cycling on the snapshot that you have provided is definitely indicative of inefficient running.

The good news is that there's a helpful community here who can assist in trying to better understand this.  I'm a fellow Ecodan user with a particular focus on it's reporting output, but there are others with far better understanding of the technicalities than me.

Thank you for the kind introduction!

Posted by: @sheriff-fatman

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Welcome to the forums.

I assume that you're getting the MelPump data via the MelCloud integration?  Assuming so, then the daily totals are those being reported by the Ecodan unit itself, and Mitsubishi's reporting tends to overstate energy usage to some extent.  Is there an electricity smart meter within the installation, as the first thing to check would be how closely the usage figures align to the actual consumption?

No, sadly not. It's all coming from the unit itself.

Posted by: @sheriff-fatman

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Welcome to the forums.

Having said that, the MelPump data suggests that the unit is cycling quite frequently at an outside air temperature of around 7°C, which will adversely impact efficiency, so there is definitely scope to look to improve how it is running if this is typical.  The COP figures across the 12 month period do also look very low in general, albeit the assumption is that the summer months are showing only performance for Domestic Hot Water, which will naturally be less efficient.  Oddly, your MelPump data doesn't look like its giving the option to show DHW COP and Heating COP separately, which is different to how the graphs display on my system.

I also don't see any options for seeing the COP separated. I assume that's because of the system itself, rather than the software?

Posted by: @sheriff-fatman

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Those with more technical expertise than me will likely reply requesting more specifics regarding your system.  The logical start point for performance issues would typically be an oversized system but a 6kW heat pump would suggest a fairly low heat loss.  Do you have any information as to what the assessed heat loss was at installation?

 I don't recall any info on that but we compared with similar places (semi-detached with 2 adults +2 kids, similar house age+renovations) and 6 kW seemed to be the right choice.  

Posted by: @sheriff-fatman

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One thing I did spot was that the flat target temp you're showing in the graph is for zone 2, but the actual data is for zone 1.  Is your system set up as a zoned one, or is there a single open loop?  On the current display the target temp needs to be shown for zone 1 so that we can see what the weather comp setting is trying to achieve, rather than the flat profile for (a presumably non-existent) zone 2.

Indeed, I should have ticked both. We have 2 zones with zone 1 being the upstairs with radiators and zone 1 downstairs with underfloor-heating. You can see them both using the link below

Melp Pump Energy report

I have considered that one of the two zones might not be configured properly but I have not noticed any obvious heat loss anywhere. Maybe it is the fact that the system is juggling two zones? 

@goodbyegas 

Hi Fellow Ecodan owner here.

Looking at your MelPump data if I read it correctly it looks like your heatpump is heating the two zones to the correct temperature - ie 20 Deg room temp and presumably you are warm enough.??

Your delta T is quite low which suggest a good flow rate. If your main concern is a low reported COP it would be worth trying to find the flow and return temperature probes that the Ecodan will be used to calculate the heat output and hence the COP. These are often just taped onto the pipes and not insulated and don’t necessarily get an accurate reading. The heat output is calculated by multiplying the flowrate x delta T x heat capacity of fluid. With Delta T being only a couple of Deg it doesn’t take much of an error to have a big impact on the COP calculation.

Your heatpump is cycling but the run times seem to be > 30 min so not really classed as short cycling, 7 Deg outside is middling tending towards mild so it’s possible your heatpump might be a bit oversized.

how does it run when it’s colder? Does it run continuously at say 4 Deg C?

I presume your system is using the Mitsubishi 2 zones capability - ie with a motorised blending valve controlled by the heatpump to blend down the water for UFH?.

Do you know if you have glycol ? From memory there is a setting in the installer menu for this - this affects the heat capacity of water so the heatpump needs to know this to calculate COP correctly.

I don’t really have experience of the Mitsubishi COP calculation as I use external monitoring on my system.

Hope that helps.

Posted by: @travellingwave

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@goodbyegas 

Looking at your MelPump data if I read it correctly it looks like your heatpump is heating the two zones to the correct temperature - ie 20 Deg room temp and presumably you are warm enough.??

Thank you.  Absolutely, it's nice and cozy.

Posted by: @travellingwave

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Your delta T is quite low which suggest a good flow rate. If your main concern is a low reported COP it would be worth trying to find the flow and return temperature probes that the Ecodan will be used to calculate the heat output and hence the COP. These are often just taped onto the pipes and not insulated and don’t necessarily get an accurate reading.

Would they be outside on the actual heat pump or closer to the water tank?

Posted by: @travellingwave

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Your heatpump is cycling but the run times seem to be > 30 min so not really classed as short cycling, 7 Deg outside is middling tending towards mild so it’s possible your heatpump might be a bit oversized.

how does it run when it’s colder? Does it run continuously at say 4 Deg C?

Here is a record from last week, when it was a bit colder and the COP dropped below 2. No continuous running.

Posted by: @travellingwave

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I presume your system is using the Mitsubishi 2 zones capability - ie with a motorised blending valve controlled by the heatpump to blend down the water for UFH?.

Yes, that's the one. 

Posted by: @travellingwave

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Do you know if you have glycol ? From memory there is a setting in the installer menu for this - this affects the heat capacity of water so the heatpump needs to know this to calculate COP correctly.

We had two radiators uninstalled during re-plastering, which resulted in some water leaking out, but I wouldn't have thought that it would have a massive impact. Maybe it does!

One other thing I noticed, where I just don't get how the heatpump makes decisions, is where it just stops and let's the pipes cool down (often at night), like last night. And about once every two weeks it needs the boosters to get back up, which is not enough and the house cools down until I restart the system.

I'll see that I find the probes and will try to calculate my own COP. Is this where I would place an external monitoring system?

Thanks again!

@goodbyegas 

Well you are warm and your flow temp at 3 Deg outside temp is only 35 degrees so you should be getting pretty decent COP. Hopefully it is just a measurement issue rather than real poor performance.

The flow and return sensors would normally be found near to the cylinder. They connect into the big white box - FTC6 which also normally lives near the cylinder. If you spot any cables seemingly attached to the pipe work that may be them- the sensor itself is a small metal tube about 5mm diameter maybe 20mm or so long, often just taped to the pipe with insulating tape. If you can’t find them send a few pictures of the pipe work around the cylinder.

your heatpump is still cycling. At 3 Deg outside one would expect continuous operation. Do you know if your rads have been balanced? Do some get hotter than others? May not be very easy to tell as 35 Deg is barely warm to the touch.

What I did to balance mine is put the Ecodan into fixed flow temp control mode (I think you are currently in Auto Adapt Mode) Once in fixed mode you can set the flow temperature manually to a much higher value - say 50 degc - this makes it easier to feel which radiators are getting either too much or not enough flow as you will be able to feel it better. You can then balance the system- various videos on how to do this - basic idea is to adjust the lock shield valves on each radiator so that water flow is distributed more or less evenly. In your case it is possible that the rads closer to the pump are too open and leading to water short circuiting back to the heatpump meaning the heat pump can’t get rid of the heat hence cycling.

Might not be the issue but certainly worth checking.

Also important that UFH is balanced correctly for same reason.

Did you get any handover pack from your installer? This should state if glycol antifreeze has been added and what concentration.

Ref radiator removal- have you checked system pressure - should be about 1.5 bar, might need topping up if you’ve had a rad off.

By the way don’t leave it in fixed temp mode - very inefficient - just use it for balancing.

Ref stopping and needing booster to get back up to temp - that sounds like something not set up right. Personally I would disable any booster heater as it could mask other issues and is costly to run - you should not need it.

It can be normal for the heatpump to stop if either the room temp gets above the target - or flow temp gets above target, it should start back up automatically once things have cooled down.

Where is your heatpump control screen by the way , please don’t tell me it’s in the airing cupboard next to the cylinder😱

when you say you have to restart it what are you having to do? Any error messages?

Some of this stuff is getting quite technical so let me know if not clear.

From memory disabling booster requires changing DIP switch settings inside FTC so may not be something you want to do/ but in any case booster should only come on if heatpump is struggling to reach temp.