Gary68

The increases in temp to above 50C is your hot water reheating you can see the tank temperature increase in line with this. If you don't want it to do this you can adjust the time hot water is heated in the schedule, its probably set to be on permanently rather than on a schedule. Or you can increase the temperature drop before it reheats When it is heating it is running at 34ish in line with your Weather compensation curve, although at 11am it is cycling on and off every 7 mins which implies only one UFH zone is calling for heat and there isn't enough water for it to heat continuously so it has to turn off till the water cools down enough then restart.

Its probably the same as you are achieving through HA but for those who don't use automation and have an Ecodan with Melcloud who want to boost heating at a cheap fixed time it is possible through the app. If you go through to the orange heating screen in the app and press actions then timer you can can create a schedule that turns on the heatpump at the fixed flow temp your controller is set to for a certain period then reverts to weather comp at the end of that period.

Agree with what has been said before, I have 4 zoned thermostatically controlled UFH downstairs, bypassed all the thermostats but the one in the hall so now works as a one big single zone.

I did a bit of a test last week when the temperature dropped overnight, in the depths of winter is was very difficult to determine what was going on as defrosts and recovery of the flow temp from defrosts was masking the issue. This isn't the case at the moment as its not cold enough, but what it did show is that with both circuits opened the flow temp had a dt of 8 where as its usually around 4 with only one circuit open. After I increased the pump speed to 4, with both circuits open the dt has returned to 4 so it would seem I had aggravated the issue with too low a flow rate which meant the HP just could raise the flow temp high enough. So will see how this works when winter hits. Changing the pump speed back to 4 has also highlighted another issue I had forgotten about. When set at a speed of 4 of 5 the pump speed seems to oscillate up and down slightly which is highly annoying as it more noticeable due to the varying frequency rather than it just being a constant frequency in the background.

That all makes sense flow temp is 55°C and its hitting 60°C before shutting off its probably overshooting due to the volume of water being so small. Its not working correctly that's for sure its getting a signal from somewhere that heat is required when it isn't. If heatmiser wireless thermostats lose connection with the UH8-RF, it opens the UFH circuits for 12mins every hour, again it doesn't look like this is what's occurring but are all the zones working as they should be and turning on when thermostats call for heat?

In the random activations the temperature is getting to 60°C very quickly suggesting its heating a very small volume of water, what temperature do you have the heating flow set to does that align with the 60°C? If so then the ashp is getting a call for heat from somewhere but none of the pumps are activating hence the rapid increase in flow temp. You said the UFH is controlled by heatmiser maybe there is an issue with how that's been wired to the ecodan controller.

So can you confirm that when the heat pump is running its trying to heat the DHW? If so, assuming it doesn't actually need to heat the hot water then you can either lower the reheat threshold or just control it through the timer so that it only heats once or twice a day depending on your requirements.

Is this the freeze stat function running the pumps, if you go to the service menu, the one that has a spanner on the far right, then down to page 2/4 there is a operation settings, in that menu there is the freeze stat function, there should be an ambient temperature its set to, on the right side this can be set as high as 20C, it runs the pumps every few hours. If you turn the temperature right down till it just ** then see if the issue stops. It doesn't sound like that but its easy to test overnight.

Thanks Joe, do you have a link, we do need to renovate the bathroom at some point and the towel rads are pretty poor emitters at low temps.

It would be more correct to say the HP doesn't turn off as the thermostat isn't satisfied- it kept the house at 20°C but the thermostat was set at 21°C and it couldn't reach that internal temp - I agree with everything else that has been said the HP is probably a little undersized for the worst case days but better that way than too big for the remaining 360 days of the year

Hi thanks for the response, the house doesn't get up to temperature the HP is on 24/7 in the depths of winter, the thermostats are set to a level that means they are always calling for heat. I will have to review this winter but what maybe happening is the unit has to defrost before getting back to 45°C and if it didn't have to defrost then it may be able to get there its just not powerful enough to get there between defrost cycles.

Hi John, When its sub zero outside, the HP never really turns off its on 24 hours a day, I learnt that at low temps, set back overnight wasn't really an option as the HP wouldn't be able to catch back up it could only maintain, so it runs 45°C constantly between defrost cycles which were occurring every hour reducing flow temp further, it would just get back up to temp then back to another defrost cycle. If then the upstairs circuit came on then it couldn't get back to 45°C hovered around 40°C if I recall correctly. I have a better handle on the weather comp curve this year and have maxed it out at 40°C to see if it can maintain temp and maybe defrost less.

Yes - that's where I was, its not a performance issue as such as the house is warm enough, I think its just on the limit of the capacity of the heat pump I will monitor more this winter. thanks for the response

Hi all, As we reach the start of the heating season, my fading memory reminded me of an issue I've had with my Ecodan since it was installed. Its not a massive inconvenience, more an annoyance to myself personally as I don't understand why its not doing what it should, the house maintained 20°C last year in the coldest months. The flow temperature will not reach target temperature when its really cold outside and the both the UFH (downstairs) and the radiators (upstairs) are calling for heat. The Ecodan has no issue getting DHW to 50°C in the depths of winter even when its run in the middle of the night during off peak prices so I know the flow temps can get that high. Its run in weather comp mode and when its subzero outside the flow temp should be 45°C. When its only the UFH calling for heat then it will reach 45°C but if the thermostat upstairs calls for heat the flow temp will drop and try to recover but never makes it back to 45°C until the upstairs thermostat turns off. Is this just the limit of the heat pump and it can't output enough heat at -5C with respect to the volume of water its trying to heat when both circuits are on? There are a lot of pumps in my airing cupboard attached to the hot water tank with the ecodan controller and I have no idea what they should be set to. There is one that relates to the HP itself that I can change the flow rate on through the ecodan controller it was set at 5 when the installer left and that was far too noisy so now set at 3, maybe I have caused the issue by reducing the flow rate too much? There is a pump for the upstairs rads a Grundfos UPM3 auto and another for the UFH circuit but then another pump that supplies the UFH manifold downstairs in a separate cupboard. These all have settings for proportional and constant curves and I have no idea what they should be set to. Any thoughts suggestions on what could be the cause or what to change to test appreciated. thanks in advance.

Hi, They are probably saying that cooling isn't supported as that model of Ecodan was on the RHI scheme where cooling has to be disabled, this is done by changing one of the dip switches on the front of the Ecodan controller. If you have a cylinder with a box on the front like the one in the video below turn off the power to everything unscrew the front panel and move dipswitch SW2-4 from off to on position., then turn everything back on once your main controller boots back up go to the heating options and cooling will now be visible. You will need to activate cooling in the timing schedule as its different for heating and cooling and you will need to turn up your thermostats to a higher than room temperature than its currently at to open the UFH circuits but then chilled water will circulate you can change the water temperature up and down on the main controller. It works really well with UFH in terms of cooling the house. When it was 40C last year my downstairs was at 20C constantly. It doesn't work well with rads and you just get pipes with no appreciable cooling you need fan coils for that to work as discussed on other posts https://www.google.com/search?q=ecodan+dip+switches&rlz=1C1GCEA_enGB995GB995&oq=ecodan+dip+switches&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIICAEQABgWGB4yCggCEAAYhgMYigUyCggDEAAYhgMYigUyCggEEAAYhgMYigUyCggFEAAYhgMYigXSAQ0yOTQ3ODAxNmowajE1qAIAsAIA&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:5ee4906d,vid:0Y4w18656d0