I've looked at the manual as I'm not a stupid person, but that is not particularly easy to follow either.
Agreed. The manual seems to be incomplete. It says what the controls are and how to access them, but not really what they do to the machine. The ecodan seems to be a good unit but it's not end-user-friendly so it all depends on the installer's skill.
if I change one setting how do I know that it's made any difference?
Monitoring. Either melcloud if you've got it (paid for it, probably), an add-on kit like openenergymonitor, or laboriously writing down numbers from various displays at regular intervals (or as near as possible).
but that's a newer version. If there's no EPC and no heat loss calculations, I don't understand how it was selected and commissioned. The service document from its last maintenance service might be useful if you have it. Otherwise, we'll probably be guessing which of the typical installation layouts the installer intended for how it should work.
The heat pump is located in a special (machine room) - all same level as the space itself.
Ah! Is the master controller (the one showing 15c in the photo above) in that machine room? If so, have you got any other temperature sensor, such as remote display+sensor unit? Otherwise, the controller may be making strange decisions based on the temperature in the machine room, not in the heated rooms.
Could you please show a photo of your heat pump, which should be located outside.
I think the serial number panel identifies the heat pump (a previous version of the 8.5kW packaged unit, whose service manual is at https://library.mitsubishielectric.co.uk/pdf/book/Ecodan_ATW_PUHZ-W85VHA2-BS_Service ) but I suspect you already noticed that and are still interested to see photos to check whether it's been placed well, and so on.
@derek-m not great pictures I'm afraid - it looks out onto land which isn't mine.
Judging by the photo, it would appear that you have had water flowing over the guttering and on to the heat pump. The unit is designed for outside use, so hopefully will still be okay. I would suggest that you get someone to clean out the guttering, and possibly install some form of gutter guard. A further alternative could be to fit a rain deflector above the heat pump.
It would be helpful if the front grill on the heat pump is also cleaned, and check that the evaporator coils are clear at the rear of the heat pump, though be careful not to bend the attached fins.
The display unit will be displaying the temperature setpoint, which appears to be set at 15C. Initially I would suggest increasing the setting from 15C to say 21C, then go to the outside unit and confirm that the compressor and fan are operating. The air coming out of the front should be cooler, which could be indicated by a suitable thermometer if you have one.
Let me know when you have completed the checks, and set the temperature back to 15C if you wish.
Hi Sarah – I have a similar sized Ecodan and your energy consumption figures are very similar to mine for Dec and Jan, directly a product of the cold spells. However I am heating 120sqm detached house, but you are heating a smaller area, an extension? to an existing dwelling that you might lose heat into perhaps? Do you have MelCloud access for data from the unit? It is hard to tell from the photo as the installation is neat and the cables not really visible, but there might be a cable running near the controller to the small wifi receiver box?
It does appear to be running in AA mode from the symbol on the front of the controller.
Given that it is in a what should be well-insulated new build I would suspect the pump might be too large, especially when you are asking for really low internal temperatures. It will cycle on and off because it has to generate a certain level of heat input when running but you are asking for so little in the rooms it keeps having to stop. And then get going again. Which is a likely source of inefficient running.
Have you been happy with performance in the past regards heating the space? I wonder whether trying to curb energy consumption due to price concerns by reducing the target temperatures in the house is not having the desired effect as the pump is effectively running continuously but just not having enough heat taken from the heating distribution in the house. It might be better to set schedules to restrict the times it does run the heating but allow it the headroom to maintain a more efficient output by hitting a higher target temperature.
Mitsubishi EcoDan 8.5 kW ASHP - radiators on a single loop 210l Mitsubishi solar tank Solar thermal 3.94kW of PV
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?
I suspect that Sarah's system is set in fixed FWT mode. If you have the time could you guide Sarah through the process of changing to either WC or AA?
I don't know which version of the ecodan introduced Auto Adaptive mode, but the icon next to the temperature in the photo shows a thermometer in a house, which means it's in either AA or Room Temperature mode. If it was in Fixed Water Temperature mode, it would be showing 💧 a water droplet. In curve mode, 📉 a graph.
To change between modes, press the menu button (bottom left), then pick Heating, then the left column should show the current mode and pressing the 🔄 button below it will cycle between AA/Room, Fixed Water Temperature and Weather Curve.
If you want to edit the weather curve on the right of that screen, you need to long-press the menu button at the start, then a pencil (edit) symbol will appear beneath the curve and you can step through some tedious-but-comprehensive-and-powerful menus to edit and then confirm or cancel the edits. There surely are youtube videos with titles involving "weather compensation ecodan FTC" but I've not enough time to review them right now sorry.
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 EPC maybe not, but without the heat loss calculations it would be difficult to know whether the pump is correctly sized: too small and it won't be able to keep the space warm enough in winter; too large and it will cost more than necessary to run, especially in spring and autumn.
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?
Not sure about the rain deflector, but turning it up and checking that the pump is blowing out cold is simply checking that it's actually able to extract some heat from the air. If it doesn't do that, then there's some pretty fundamental problem such as a motor not motoring.
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.
Well, it sounds from the age of the building, the size and the low temperatures that it shouldn't be using that much electricity. Are you sure something might not have broken since day one? Or maybe it never worked right but the electricity prices are now forcing investigation.
This is what I see on settings - looks like it's set to target room temperature mode - if I change to target flow temperature - then 47degree C appears in the box and I don't think it's ever been in compensation curve mode
@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?
attached somewhere near the cylinder or controller then you should be able to connect to Melcloud (there will be a green light against 'unit' – I think – if it is all connected to wifi). If you don't have this it makes things more difficult to diagnose as it gives easier access to comprehensible info about flow and return temps, and running periods.
You seem to be in touch with the original installers, so they should have details of the design spec they worked to set the system up, including heat loss calculation. They are best placed to assess whether it is functioning as it should be, the hp unit and its settings have to work with the heat delivery system and the way you use it, and every house is different in that regard.
I am having difficulty envisaging your arrangement and relationship to the house exactly, but if you are effectively semi-detached then that should be a good buffer against heat loss along a good length of your 'external' walls. One thing that I might suggest you look at is whether the door to the main house is a source of draughts. You could have a pooling of colder air coming in around it?
Mitsubishi EcoDan 8.5 kW ASHP - radiators on a single loop 210l Mitsubishi solar tank Solar thermal 3.94kW of PV
Maybe we need to go back a step. You have a 60m2 new(-ish) built space with ufh and a 8.5kW Ecodan. It's using about 30kWh per day in winter to 'heat' the space to 15-18 degrees plus provide HW. It looks like you're controlling things by Room Temperature mode on the main controller plus you have some sort of thermostat in each of the three rooms.
Firstly, that sounds a big ASHP in a small space but that's not necessarily a huge problem in itself. Where I think you may have issues is the way you are controlling the ASHP. You are effectively splitting up your already maybe too small space into three even smaller ones and trying to control these separately. That's not the way to run an ASHP efficiently.
I don't know but I doubt you have three 'zones' as defined by Mitsubishi (the Ecodan controller can only handle two for one thing); I suspect you have a single zone with independent thermostats in each room that shut off the ufh flow when set point is reached. If you do, then you'll be asking the ASHP to heat very small areas at a time as the three rooms heat up and cool independently. For example you could be asking your 8.5kW ASHP just to heat your bathroom if the other rooms are up to temperature. This isn't going to work very efficiently as there won't be enough water flow to heat efficiently.
If the Ecodan controller is running in Room Temperature mode, it has to have a room temperature to monitor. Unless you have a remote thermistor connected to the main control box or a Mitsubishi wireless thermostat, it's going to monitor the temperature wherever the main control panel is. If that isn't in the living space then that isn't going to work properly. I've also heard it quoted that Ecodan Room Temperature mode doesn't work well with ufh but I have no experience of this.
A question on your hot water. How much do you use? I notice that it's at 53 degrees on the controller. That's quite hot and if you use a lot this could be a big chunk of your kWh used.
You could try running your system as a simple single zone and see what happens. If you set the main controller to fixed flow, say 40 degrees and all the thermostats to say 19, then that will let you know if the system is working. If there is nothing significant wrong and it's reasonably well designed then the ASHP and your ufh should be able to heat your space easily to that target. If it can't then something else is wrong. If it can then you can work from there.
@kev-m you're right with what you say - I do use thermostats in the three zones. The bathroom has always been low because it always seemed to be calling for heat - which then seemed to make the fan work - which then used more electricity - so I set it to frost setting. The hot water is for a shower and they are not long 20 minute showers!! I'm happy to try in fixed flow mode - I think mine says "target flow temperature" - picture of thermometer and droplet together, rather than house with thermometer - I'll set to 40 degrees (when I looked yesterday to switch was set to 47) and see how that goes. The weather currently is milder and so with my current settings electricity is low (so I know it's not the rest of the house using so much electricity - it is the ASHP) - if I try this for the next two days, I will see if the consumption goes up. Thank you for all your help.
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