Posted by: @jasper01

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I've been running the system like the gas central heating system we have been used to for years in previous homes. However, I know this is not the best way. 

Not only "not the best way", but it probably won't even work unless you've got the central heating flow temperature set to gas-style high temperatures, which will cost a bomb. At cheaper low temperatures, it probably can't move enough heat into the emitters in the short "on" times. It takes a good 30+ minutes to bring most heat pumps up to temperature.

Posted by: @jasper01

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I have now set this to cold end 40 degrees and -3 and the other one at 36 degrees and 8 degrees. I sort of understand why, but not totally sure. Does this sound right?

It sounds a bit shallow to me, but it could be right and we can't really tell without seeing the heat loss calculation for your home. I suspect your H/A haven't given you that and asking for that would only lead them to suspect you're "fiddling" again.

Now, a possible saving grace: you have an ecodan so you might not need to figure out the curve for yourself. If the right switches are set in the unit (and they are by default), the "room temperature" mode is replaced by an "auto adapting" mode where the controller is supposed to learn for itself what temperature is needed given the current indoor and outdoor temperatures. That indoor temperature comes off the Mitsubishi control panel, not the wifi thermostats, so is it in your living space and not in a cupboard or something silly?

You might find you need to change the learning Interval in Menu: Service: Operation Settings: Heating Operation: Room Temp Control, which I'd guess at 20 minutes for a small new build.

Posted by: @jasper01

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We have wi-fi thermostats in every room. There's a control panel for those in the kitchen and I have no idea how to operate it.

The living room and hall/bathroom I've set to 20 degrees. Bedroom 1 16 degrees, bedroom 2 / office 19 degrees.

I'd only use that to prevent rooms from overheating and try to use the radiator valves to control temperatures normally. If you set thermostats too low, the heat pump may shut off or reduce down before all rooms are hot. You can find a lot of grumbling about on/off thermostats in other discussions on this site.

Good luck! Do you have melcloud or another app so that you can see what the system is doing in near-real-time?

Posted by: @jasper01

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The last time the H/A engineers came out they locked me out of the settings !!! They told me I shouldn't be 'fiddling' with it, or else they won't come out. 

By the way, I'm pretty sure locking the heating controls is not legal and definitely not if you're paying for the energy used. Right to quiet enjoyment and all that jazz. But I can understand if you don't want to have that fight and risk eviction these days.

@mjr thank you for your reply!

I should have said its UFH.

The control panel is in the hall. However, I appear to be still locked out of the service settings. I'm sure when we first moved in, I'm sure I remember being able to peruse this.

Partly, the reason why I want to understand more is so I can force the hand of the H/A to sort it out. I doubt I will be able to understand enough to do so. But I am trying; if only so I have a strong argument with evidence to present to the H/A. These bungalows are meant for elderly people - all the others in the street are struggling. we had ours set on the constant 45 degrees ( meant for swimming pools etc); as has a neighbour.

I will be getting onto the H/A again forthwith about the service settings, unless anyone knows how I can get back into it. I can access the list of operation settings but then when I choose an option it asks me if I want to shut down the system yes or no?

@mjr I have no idea what the heat loss calculation is. We weren't even given an instruction pack. If it hadn't been for a chance conversation with the next door neighbour, we'd have let a carpet fitter bang nails through the floor!

Hi Jasper01

Posted by: @jasper01

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I have now set this to cold end 40 degrees and -3 and the other one at 36 degrees and 8 degrees. I sort of understand why, but not totally sure. Does this sound right?

I’d say you’re looking roughly right at the 8c end of the curve but I would think you might be a bit cold at the -3c end. Unless you have a super insulated home. 

I guess it all depends on how accurately the size of your heat pump has been calculated. 

I would suggest setting your cold ambient end of the curve at about 52ishC @ -3

This is just for starters and you will probably still be adjusting later anyway. 

1. So how well do you know the buttons of your main controller? 
   if you press the back button the screen will light up.
2. press and hold the function button positioned under the i logo which should show you your existing set temperatures eg the hot water target temperature and the set Flow Temperature which your compensation curve is targeting to heat your radiator water based on the current outside temperature. *make a not of the target temperature*
3. Now can you identify the outside temperature from your thermistor readings. You can get this reading from the service menu. Open the main settings menu and select SERVICE. enter password which is normally 0000 then scroll down to thermistor readings and select it. You will see all thermistor readings on one screen. The lowest one is probably the outside ambient reading. 

You now need to test on 2 contrasting, cold and mild days how well the existing curve warms your house.

here’s a routine to adjust one  point on your curve:

Then raise the room stat to 24C to allow the HP to operate just from the WCcurve  setting. It helps also if all your rad stats are calling for heat rather than shutting down.  (If your curve is too low you will never reach room stat temp. - If it’s too high you will pass the room stat temp)

After 3 hours check if the temperature is at the right comfort level in your main living space.

Here is a starting point  let me know how you get on then we can then look at adjusting the curve   
hope this helps and if anyone thinks this is wrong please let me know….👍🏼

I would suggest setting your cold ambient end of the curve at about 52ishC @ -3

I don't understand what this means? Sorry...I don't understand any of it....its so frustrating....what does it mean if the curve is too low??? sorry, it just doesn't make any sense.

Also, I can't access service settings. The H/A locked me out of the whole control panel the other week. I called Mitsubishi to get back in, but still can't access service settings...just says do I want to shut system down?

My only other option to all this is to pay for an expert to come in and set it up for me. Does anyone know of anyone who could do this in the Worcestershire area?

@sunandair right so I was able to access the thermister reading - lowest figure was 9 degree c (Th7)

DHW is 55 36 set temp (FLOW)

Posted by: @jasper01

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Hello, 

I have trawled through some information on here, (and elsewhere), but I'm finding this ASHP malarkey, bewildering to say the least!

We rent the property (H/A) and they have been useless. Considering we only have a small 2 bed bungalow and ASHPs are supposed to be THE most efficient thing going, I could not understand for the life of me, why they system seemed incapable of heating the property; (new build 4 years old).

I tried to get the H/A engineers to get to the bottom of it, but I don't think they are clued-up enough. 

I've been running the system like the gas central heating system we have been used to for years in previous homes. However, I know this is not the best way. 

I had it running on room thermostats and had it on that setting. It came on at around 7 am - off at 10 am. On again at 2pm , off at 10pm. During the very cold spell Dec 22 we had it running 24/7, were still cold and it cost around £10 per day. Only really the lounge was warm and only because its open-plan to the kitchen, so the cooker helped to warm it up more.

Today, I've been looking into the compensation curve thing which I still don't really get. I have to have it explained VERY simply if anyone is able to help!

However, I delved into those settings - the 'cold end' (?) was set at 50 degrees at the top of the curve and - 30 at the bottom end. The other setting was also way off.

I have now set this to cold end 40 degrees and -3 and the other one at 36 degrees and 8 degrees. I sort of understand why, but not totally sure. Does this sound right?

I have also now set it run constantly.

We have wi-fi thermostats in every room. There's a control panel for those in the kitchen and I have no idea how to operate it.

The living room and hall/bathroom I've set to 20 degrees. Bedroom 1 16 degrees, bedroom 2 / office 19 degrees.

I'm now waiting with bated breath to see if over time - I guess it'll take a good day - to see if this makes any difference to fuel consumption and comfort levels. ( I currently feel quite chilly ). 

Are there any other settings I should be looking at?

The last time the H/A engineers came out they locked me out of the settings !!! They told me I shouldn't be 'fiddling' with it, or else they won't come out.  I had to phone Mitsubishi to find out how to un-lock it.

Any help for a bit of a thicko here gratefully received. I have been tearing my hair out with since we moved in, in August last year. I HATE the thing if I'm honest !

 

 

I usually suggest initial Weather Compensation (WC) settings of Leaving Water Temperature (LWT) of 50C at an outside air temperature of -5C, and LWT of 25C at an outside air temperature of 20C. But since you have clarified that you have UFH, the colder end may be better at 40C rather than 50C.

As a quick check, increase the setting of the thermostat located in the living area by 2C, then see if the room temperature increases. Wait until the temperature stabilises. If the temperature is much higher than desired, then the WC setting is too high.

If possible provide some photo's of your thermostats, controllers, UFH controls, water pumps and any other equipment that may be present. 

Posted by: @jasper01

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I would suggest setting your cold ambient end of the curve at about 52ishC @ -3

 

I don't understand what this means? Sorry...I don't understand any of it....its so frustrating....what does it mean if the curve is too low??? sorry, it just doesn't make any sense.

Also, I can't access service settings. The H/A locked me out of the whole control panel the other week. I called Mitsubishi to get back in, but still can't access service settings...just says do I want to shut system down?

My only other option to all this is to pay for an expert to come in and set it up for me. Does anyone know of anyone who could do this in the Worcestershire area?

 

 

 

Let me explain a little bit about heat loss and weather compensation (WC).

If there is a difference in temperature between the inside of your home and the outside, then heat energy will flow from the higher temperature to the lower one.

If the indoor temperature is 20C and the outside temperature is 20C, there is no temperature difference so no heat loss.

If the indoor temperature is 20C and the outside temperature is 10C, there is 10C temperature difference so the heat loss could be say 1kW.

If the indoor temperature is 20C and the outside temperature is 0C, there is 20C temperature difference so the heat loss could be say 2kW.

The heat loss is therefore dependent upon the temperature difference, the size of the property and how well insulated it is. Larger property, greater heat loss, better insulation level, lower heat loss.

To keep the indoor temperature fairly constant, the heat energy supply needs to match the heat energy demand (heat loss).

With a heat pump, this can be done with reasonable accuracy by means of WC control. A temperature sensor measures the outside air temperature, and the heat pump controller compares this value with that from the WC curve, and calculates the required LWT.

If the WC curve is set for a LWT of 25C at an outside temperature of 20C, and a LWT of 40C at an outside temperature of -5C, then the actual slope is given by:-

Change in LWT divided by change in outside temperature = (40C - 25C) / ( 20C - (-5C)) = 15C / 25C  = 0.6C

So if the actual outside temperature is 5C, the calculated LWT will be 25C + (20C - 5C) x 0.6C = 25C + 9C = 34C.

The heat pump controller will therefore control the heat pump to produce water at approximately 34C, which should provide sufficient heat energy to keep the indoor temperature at approximately 20C.

If the indoor temperature starts to increase, then the WC curve is set too high, so the slope of the WC curve needs to be adjusted by say changing the cold end setting to 40C at -10C rather than 40C at -5C. Obviously if the WC curve is too low, it may be better to change the curve to 45C at -5C.

I do believe that for the Ecodan controller to accept changes in settings in the installer/service mode, it is necessary to shut it down and restart, but maybe some Ecodan owners can confirm this requirement.

@derek-m thank you everyone so far!

Seems its 1 step forward 2 back.

I will get some pictures organised tomorrow and see if that helps you HP super sleuths! I really grateful for your help. None of us can afford to be spending money unnecessarily these days and even if I had money to burn, I would rather not!  Thanks again, I'll be back soon.

Posted by: @jasper01

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Also, I can't access service settings. The H/A locked me out of the whole control panel the other week. I called Mitsubishi to get back in, but still can't access service settings...just says do I want to shut system down?

Yeah, it does that. I say yes to shutting down, change the settings, then when finished and exited back to the home screen, press :power: to start the system back up.