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How to best configure my Mitsubishi heat pump to work effectively?

 
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Air Source Heat Pumps (ASHPs)
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 CheshireCat
(@cheshirecat)
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Joined: 3 years ago
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Topic starter 29/11/2022 3:40 pm  

Hi, 

I've a Mitsubishi 14kWh Ecodan which has just been fitted ( commissioned at the end of last week). 

We have the room stat (Mitsubishi) and FTC. 

Our house is around 180m2 with a variety of ages of the house. (Some parts 1840, some early 00's - with varying and questionable insulation in some parts - though we're working on that). 

Installers commissioned the system, but I would say in a way that is very reflective of a twice on/off a day system with a heat curve where the lowest flow temp is 25 deg c - even at an indoor temp of 20 dec c. 

It's a Mitsubishi FTC controller - but it doesn't currently have energy monitoring ( annoying and hopefully to be resolved shortly). 

The heat pump is cycling off and then throwing hot water through the rads - so I need to get a more even temp.  

Installers set combo of curve and room stat - but the crazy heat up/ off cycle is still happening.  So - how do I get this to stop happening? 

I adjusted the curve, which has helped a bit in some parts of the day, but still getting lots of cycling. 

I have the Mitsubishi app - but it's not very user friendly and I'm at a total loss to know what it's trying to tell me.   

I've tried switching weather comp only on - but the system stayed at 18 overnight which was far too warm for comfort. (I think this is because the app is set at 18 - it seems to have overridden the controller and I don't know how to get that back...)

I know the set back needs to just be a couple of degrees but the commissioning engineer put the set back at 10 degrees and I KNOW that's not correct.

I tried following a reset the curve at 8 degrees from Heat Geek, the cycling is less, but still present.  

I'm aware that this is not an easy ask, but I've no confidence that the installers will give me advice that works correctly for an ASHP as they seem quite determined to give me a set up that reflects my old boiler!

Help is much appreciated.  

 

 



   
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 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
29/11/2022 3:48 pm  

Posted by: @cheshirecat
↑

Hi, 

I've a Mitsubishi 14kWh Ecodan which has just been fitted ( commissioned at the end of last week). 

We have the room stat (Mitsubishi) and FTC. 

Our house is around 180m2 with a variety of ages of the house. (Some parts 1840, some early 00's - with varying and questionable insulation in some parts - though we're working on that). 

Installers commissioned the system, but I would say in a way that is very reflective of a twice on/off a day system with a heat curve where the lowest flow temp is 25 deg c - even at an indoor temp of 20 dec c. 

It's a Mitsubishi FTC controller - but it doesn't currently have energy monitoring ( annoying and hopefully to be resolved shortly). 

The heat pump is cycling off and then throwing hot water through the rads - so I need to get a more even temp.  

Installers set combo of curve and room stat - but the crazy heat up/ off cycle is still happening.  So - how do I get this to stop happening? 

I adjusted the curve, which has helped a bit in some parts of the day, but still getting lots of cycling. 

I have the Mitsubishi app - but it's not very user friendly and I'm at a total loss to know what it's trying to tell me.   

I've tried switching weather comp only on - but the system stayed at 18 overnight which was far too warm for comfort. (I think this is because the app is set at 18 - it seems to have overridden the controller and I don't know how to get that back...)

I know the set back needs to just be a couple of degrees but the commissioning engineer put the set back at 10 degrees and I KNOW that's not correct.

I tried following a reset the curve at 8 degrees from Heat Geek, the cycling is less, but still present.  

I'm aware that this is not an easy ask, but I've no confidence that the installers will give me advice that works correctly for an ASHP as they seem quite determined to give me a set up that reflects my old boiler!

Help is much appreciated.  

 

 

 

You could start by turning any thermostats up to 23C, then see if that has any effect upon the cycling.

 



   
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 CheshireCat
(@cheshirecat)
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Joined: 3 years ago
Posts: 18
Topic starter 29/11/2022 3:53 pm  

Thank you.  I'll do that now.

 



   
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 CheshireCat
(@cheshirecat)
Eminent Member Member
Joined: 3 years ago
Posts: 18
Topic starter 29/11/2022 3:55 pm  
image

 

This is an example of what I mean. 

 



   
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 CheshireCat
(@cheshirecat)
Eminent Member Member
Joined: 3 years ago
Posts: 18
Topic starter 29/11/2022 3:59 pm  
image

By contrast - 13:00 for an hour is relatively stable. This is reflective of the period 10 am to 1pm.  Cycling happened at 9:00 and 15:00

 



   
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 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
29/11/2022 4:07 pm  

@cheshirecat

It would appear that the heat pump was heating the hot water cylinder, when the Flow Temperature went above 50C. Once the DHW was up to temperature it switched back to CH, and has gradually raised the Flow Temperature up to the present 40C.

I would suggest that you see if the Flow Temperature stabilises, and if the indoor air temperature remains constant.



   
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 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
29/11/2022 4:21 pm  

@cheshirecat

When you say that you have a Mitsubishi 'room stat', do you know if it is actually a thermostat or a temperature sensor? Does it have a model number?



   
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 CheshireCat
(@cheshirecat)
Eminent Member Member
Joined: 3 years ago
Posts: 18
Topic starter 29/11/2022 4:22 pm  

Thank you! 

Just need to work out how to solve the app/ room stat overriding the controller now! 

 



   
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 CheshireCat
(@cheshirecat)
Eminent Member Member
Joined: 3 years ago
Posts: 18
Topic starter 29/11/2022 4:40 pm  

It’s a wireless remote controller. 

PAR-WT50R-E

 

 



   
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 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
29/11/2022 4:40 pm  

Posted by: @cheshirecat
↑

Thank you! 

Just need to work out how to solve the app/ room stat overriding the controller now! 

 

Please explain what you mean?

Looking at the first graph, it would indicate that your heat pump is carrying out the hot water reheat cycle, which will be set in the schedule.

The second graph would appear to show that your heat pump is operating normally, without any obvious cycling, but is responding to the variation of the outdoor air temperature.

If that is the case then you may wish to reset the 'room stat' to its original setting.

 



   
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 CheshireCat
(@cheshirecat)
Eminent Member Member
Joined: 3 years ago
Posts: 18
Topic starter 29/11/2022 5:59 pm  

They told me that any manual temp change  would revert at the next programmed change. 

It’s set to 17 during the day and 15 at night on the main controller/programmer.

I manually changed it to 18 in the app yesterday and it stayed at 18 all night although at 10pm it should have switched back to 15.  

 



   
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 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
29/11/2022 6:23 pm  

Posted by: @cheshirecat
↑

They told me that any manual temp change  would revert at the next programmed change. 

It’s set to 17 during the day and 15 at night on the main controller/programmer.

I manually changed it to 18 in the app yesterday and it stayed at 18 all night although at 10pm it should have switched back to 15.  

 

You will need to check the settings in the schedule. If you read through the manual it should explain how to do this, if not there will be a YouTube video I feel certain.

Who set the indoor temperature at 17C and 15C? It seems rather cold to me.

 



   
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