OK - a couple of pictures showing the consumed electricity v delivered energy. Might sound a stupid question - but says in december consumed was 516 - does that mean that my whole system only used that much energy for December? Looking at figures from my solar stats for last year:
June 417kwh / July 437 / August 437 / Sept - 416 / Oct - 410 / Nov - 500 / Dec - 1.04mwh / Jan - 860
Ok, so if I understand correctly, you have a PV array linked to this app, which also measures total house usage somehow. I presume these figures are for total house usage in these months and match the amounts Octopus billed you for?
From the EcoDan controller we can tell you have c500kWh extra electricity usage in both Dec and Jan above that the ASHP has used. That's a lot. I have PV installed and my combined import for June-Sep is less than a single month of yours. I think there's something not right with the electrical installation.
That's not to say the ASHP is faultless though!
Mitsubishi EcoDan 8.5 kW ASHP - radiators on a single loop 210l Mitsubishi solar tank Solar thermal 3.94kW of PV
These numbers are for the whole house - including the ASHP. June for example - 417kwh - 344 from PV and 73 from grid - looking at octopus bill - this just about matches - PV does 1 june to 30 June - Octopus 25th to 24th. Looking at December - charged from 25th November to 24th December - 923 kWh
OK - a couple of pictures showing the consumed electricity v delivered energy. Might sound a stupid question - but says in december consumed was 516 - does that mean that my whole system only used that much energy for December? Looking at figures from my solar stats for last year:
June 417kwh / July 437 / August 437 / Sept - 416 / Oct - 410 / Nov - 500 / Dec - 1.04mwh / Jan - 860
These figures are for total usage – I think I assumed they were just grid import, but fortunately not! But they are total house usage, only reading the controller on the heat pump will give you the heating consumption of your house. So the the figure for today of 17 you gave earlier will be total use taken from the app, and though it will include the energy being used by the heat pump you won't be able to get the figure from the heat pump controller itself until tomorrow as it doesn't record it until the end of the day. And you would have to make a note of it if you wanted a record as it then is replaced 24hrs later!
60kW (or a bit less) is not at all a high figure for the first few days of the month, but you are not getting the heat out you would like to reach the temperature you want. Your consumption and generation figures for 2022 shows a system being not at all efficient, but not using an unreasonable amount of energy.
I don't have UFH and am no expert, but in the absence of anyone else offering their knowledge in how to analyse your setup I'll do my best and suggest what I would do. The general advice is to have the heat on for long periods at as low a temperature as you can run. As an 8.5kW pump seems quite generously sized for a small area it may be that the pump is losing efficiency trying to keep a low output. I have read of individuals using their slabs like an old fashioned storage heater, using a v cheap Octopus night rate to run the pump hard and heat the slab and then just let it cool during the day. But this depends very much on the financial benefit of running the pump inefficiently. It might be better to find a compromise between these approaches – you said you have thick limestone on top of the slab so it won't be a responsive setup, but as long as the heat gets into the slab in an efficient manner then it is there to trickle in to the rooms. This gives you some flexibility to avoid the inefficiency of running a high water output temperature or when outside temperatures are low.
Have you set heating schedules in the controller? Or is it running how the installers set it up? Which I am guessing might be on an always on schedule, possibly even over summer, relying totally on a thermostat to turn it off.
I would adjust the heating schedule so it is 'on' availability is reduced, perhaps to 8am to 10pm, thereby not running the pump when overnight outdoor temperatures are colder. A slightly higher output requirement when it is running during the day should help the pump run for longer periods, and will be supported by your own solar generation.
Finding the best water flow temperature is trickier, especially with no heat loss value to aim at, and no Melcloud to give feedback on what the running temperatures are actually doing as you try out different settings. KevM said he doesn't think the room temperature mode is ideal for UFH systems, and I think that is probably especially true in your case as the room thermostats are linked to the UFH manifolds not the EcoDan flow controller. Room temp mode may well be utilising the inbuilt thermistor in the controller, which is in the plant room and not one of the living spaces!
If you want to run fixed temp flow mode then I would suggest set it at 30 and then increase as necessary, I don't think you want to UFH flow to be too high with a heat pump. I suggest this cold-up approach as you are obviously concerned about cost and I think would prefer this to setting it higher and then reducing down if too warm.
Curve mode should be more efficient overall as it tracks external temps, but the one set up by the installers will be a best guess starting point. You can offset the actual flow temperature down against the curve and then bring it up to find the most effective values, and then even edit the curve to match – this is what I and most others have done. But it might be harder to gauge with a UFH system I imagine!
But you might need to raise the thermostat temperatures to allow the heat pump to work more consistently – for a period at least. You need to know a particular setting produces too much heat in order to make the adjustment before capping it with a thermostat, but a cold to warm approach as you are using now should work well too.
I'd ask your installer about get MelCloud capability added as it makes the running of the system more visible to you as an end user, and offers ways to adjust settings in a more direct way than button-pressing the controller.
I hope all this helps!
Mitsubishi EcoDan 8.5 kW ASHP - radiators on a single loop 210l Mitsubishi solar tank Solar thermal 3.94kW of PV
Firstly - thank you so much for taking the time to reply - this has been an education for me I can tell you. I have disliked this system from the word go and I'm hoping I might get to like it!! OK - what you are saying makes sense - I have changed the schedule (learnt how to do it!!) - as you say this was set by the installer, I've never touched it - was set for 04:00 until 21:00 - I have changed this to 08:00 until 21:00.
I think that I will up the thermostats in each room to 18 in living area and 16 in bathroom and bedroom. I will do that to start tomorrow morning.
I will also change the fixed flow temp to 30, as you suggest.
yesterday total 35 kWh - NOTE THIS IS NOT JUST FOR THE ASHP - THIS IS FOR WHOLE HOUSE - but I have a general run rate of about 15 to 20 kWh for the whole house - I looked at Septembers figures and it didn't once go above 20 kWh used in a day - which you would expect when weather is mild.
The thermostats show 15 degrees in each room - they are calling for heat - as have changed them to 18 in living room and 16 in the other two rooms. It will be interesting if they manage to reach this temperature today. Yesterday in the living room with solar gain - did get up to 17 - not as sunny here at the moment.
09:00 - used 13kwh so far today - yesterday total usage 28kwh
rooms are bathroom 15 (target = 16) - calling for heat
bedroom 16 (target = 17) - calling for heat
living area 16 (target = 18) - calling for heat - this space last night at 19:30 was at 17 and calling for heat - during the 12 hour period of the day had not managed to get up to 18 - possibly may today !!
WEATHER OVERNIGHT WAS ABOUT -2 - so a cold one and frost still on the ground at 09:00
I have the target flow temp at 35 degrees - sorry Harriup - I chickened out at putting it too low !!!
@derek-m Hi, Thanks for your reply. No I've never done any heat loss calculations and I don't have an EPC showing energy consumption - to be honest when this system was installed I thought it would be the best thing since sliced bread - better for the environment, would heat up my space really lovely in the winter and use less energy. In my experience - it is really complicated to understand the controls - if I change one setting how do I know that it's made any difference? Changing the setting from 21 to 15 (as stated in previous reply) - I've no idea what this really is - this is on the control panel separate to the individual controls in the space itself. Also, having to do heat loss calculations/EPC showing energy consumption etc etc!! I'm just happy when the temp outside is better and the ASHP doesn't need to come on and now dislike the really cold weather. Ironically I wish we had installed a wood burner in this new space too and have even looked at ways that we could possibly get one in. I phoned the installer last week (McGregor Heating) - they were really good and spoke to someone mentioning that usage was really really high and possibly the settings may need to be looked at - the woman was very nice and just said in a "knowing way" - that the settings were mostly likely correct. I took this to mean, yes electricity bills will be high and when it's cold it has difficulty coping.
The heat pump is located in a special (machine room) - all same level as the space itself. I have windows, but they are all double glazed and new 7 years ago - the whole space is only 7 years old. I've attached a couple of pictures of the hot water tank.
I have just had a look back through your previous messages to see if I missed anything. One thing that I would suggest is that you get all the uninsulated pipework correctly insulated.
wow thank you all so much for taking the time to send me a reply - I really do appreciate it and some of your suggestions. The EPC and heat loss calculations - I don't ever recall seeing them - but as it was put in a new build would we have needed them? The bottom line is, this system has been expensive to run from day one - so that is 7 years ago - it's only become more apparent since the cost of electricity has increased. Having to put some sort of rain deflector and also to change the setting of the main control panel to 21 and then go outside and try and check to see if cooler air is coming out of the compressor , I have absolutely no idea why I might be doing these things and really this is this what I need to do? With the figures I've provided - i.e. usage and size of space (small!!) could I potentially have a problem? I would have had this from day one as nothing has been changed. Why would anyone want to get one of these?
You should have been provided with all the relevant documentation in the handover package when construction was completed.
To be able to help you resolve your problems, it is necessary to develop a mental picture of how your system has been installed and is being operated. Obviously, if you cannot provide the necessary information then that limits what help and assistance that can be provided.
I suspect that you may have a problem, since you are only heating your extension to 15C, and using the same amount of electrical energy as someone heating a property twice the size, to a temperature of 20C - 21C.
@harriup I'm not sure about melclod - certainly never used this since we've had the system installed. It makes sense what you say - we do have stairs which go up to the main house - it's only up to a room and bathroom and then a door which separates from rest of house which I usually keep closed - I had wondered about heat loss here - but there's not much I can do - but actually the stairs are very close to the machine room and in the most insulated part of the new build. What you say also about it working too hard just to give very little output of heat, because we're not calling for it - that could be true - not sure what I would need to do to change this. I've set times on the thermostats in each of the three zones when to call for the heat. One zone will never call for it as is frost setting. It almost seems counterintuitive to me to let the system do it's thing - really in the cold weather it appeared to struggle to heat up the slab. We put 40mm limestone slabs down and I've thought perhaps they weren't right - but apparently they are quite good for these kind of systems. It's been very difficult to know what we should do. Should I be changing to the compensation curve mode when it's cold?
Was the floor adequately insulated underneath the UFH pipes?
hi - attached are three photos of the general layout - including where the UFH is - I have a whole folder of documentation - most of it to do with the manifolds and layout - they don't mean much to me - but if it helps I can photograph and attach? I am slowly coming to the conclusion that the settings were all wrong and using the "target room temp" setting was not right for me.
OK - a couple of pictures showing the consumed electricity v delivered energy. Might sound a stupid question - but says in december consumed was 516 - does that mean that my whole system only used that much energy for December? Looking at figures from my solar stats for last year:
June 417kwh / July 437 / August 437 / Sept - 416 / Oct - 410 / Nov - 500 / Dec - 1.04mwh / Jan - 860
September minimal running of the system and from oct - only on low heat for the 60 sq metres
Also attached pictures of the manifold
Looking at the photo's of the UFH manifold, they appear to show a water supply temperature of possibly 19C, and a return temperature of 15C. I therefore suspect that the heat energy is not getting to your UFH pipework.
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