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Mitsubishi Ecodan 8.5kw working as on-off machine

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(@bialk)
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66 kWhs
Joined: 1 year ago
Posts: 5
Topic starter  

My Mitsubishi Ecodan 8.5 kw Heat pump doesn't work as inverter continuosly,  but more like as an on-off machine. I tried to change many settings on controller, but it still works 30 minutes and then going off 5-10 minutes. Please help how to setup it work continuosly without pause and not to stop when reaches flow temperature (37c). Here are thermistors readings

20230129 112926

And screen shot of consumption from the PV invertor, as Heat pump is connected to it:

Screenshot 20230129 195230 ShinePhone
This topic was modified 1 year ago 2 times by bialk

   
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(@kev-m)
Famed Member Moderator
5561 kWhs
Joined: 3 years ago
Posts: 1299
 

Posted by: @bialk

My Mitsubishi Ecodan 8.5 kw Heat pump doesn't work as inverter continuosly,  but more like as an on-off machine. I tried to change many settings on controller, but it still works 30 minutes and then going off 5-10 minutes. Please help how to setup it work continuosly without pause and not to stop when reaches flow temperature (37c). Here are thermistors readings

20230129 112926

And screen shot of consumption from the PV invertor, as Heat pump is connected to it:

Screenshot 20230129 195230 ShinePhone

Some more information required, as a start:

Are you running in Weather Compensation mode?  

What is the outside temperature where you are?

Have you radiators or underfloor heating

What size/type is your house?

Have you any form of thermostats working in zones/rooms?

 

 


   
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(@bialk)
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66 kWhs
Joined: 1 year ago
Posts: 5
Topic starter  
  • 1. No WC active. I tried it, but no change. Now it works on 37c heating mode water temperature. 

    2. Outside temperature is from minus 3 to plus 6 Celsius.

    3. Have 3 radiators and 2 heat water convectors. No DHW installed.

  • The house is 90 m2, inside Temps are 21-23c. 
  • No thermostat in rooms. Only controller from FTC to one room.

I wonder why Heat pump stops, instead working with less power. When outside temperature is under 0c it may defrost, but it tends to stop even when Temps are 5-10 degrees. 

 

Screenshot 20230130 110622 Samsung Notes

 

This post was modified 1 year ago by bialk

   
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(@kev-m)
Famed Member Moderator
5561 kWhs
Joined: 3 years ago
Posts: 1299
 

Posted by: @bialk
  • 1. No WC active. I tried it, but no change. Now it works on 37c heating mode water temperature. 

    2. Outside temperature is from minus 3 to plus 6 Celsius.

    3. Have 3 radiators and 2 heat water convectors. No DHW installed.

  • The house is 90 m2, inside Temps are 21-23c. 
  • No thermostat in rooms. Only controller from FTC to one room.

I wonder why Heat pump stops, instead working with less power. When outside temperature is under 0c it may defrost, but it tends to stop even when Temps are 5-10 degrees. 

 

Screenshot 20230130 110622 Samsung Notes

 

@bialk

An 8.5kWEcodan will be able to modulate down to 3-4kW at your flow and ambients.  Have a look at page A-57 here.

https://library.mitsubishielectric.co.uk/pdf/book/ATW_Databook_R32_2020#page-60-61

If it takes yours less than that to heat the flow to 37 deg it will have to cycle. 

You may be able to reduce this by changing the range above and below your set temps where the ASHP stops and starts.  Have a look at page 38 here.

https://library.mitsubishielectric.co.uk/pdf/book/Ecodan_FTC6_PAC-IF071-3B-E_Installation_Manual_BH79D843H02#page-38-39

A bit of cycling is OK.  2-3 times per hour is usually quoted as nothing to be concerned about.   

 


   
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(@bialk)
Eminent Member Member
66 kWhs
Joined: 1 year ago
Posts: 5
Topic starter  

Thanks for replay. It seems my house is well insulated and Pump reaches Temps quickly. What do Min, Normal and Max mean in this table? Should I change to Min settings through Quiet mode (one bar) in service menu?

Screenshot 20230130 124713 Samsung Notes

   
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(@kev-m)
Famed Member Moderator
5561 kWhs
Joined: 3 years ago
Posts: 1299
 

Posted by: @bialk

Thanks for replay. It seems my house is well insulated and Pump reaches Temps quickly. What do Min, Normal and Max mean in this table? Should I change to Min settings through Quiet mode (one bar) in service menu?

Screenshot 20230130 124713 Samsung Notes

I'm not exactly sure what nominal is; I think it's the compressor speed its official ratings are done at. P55 of the data book gives some info.  Min is lowest, max is highest and medium is 80 percent of nominal.  I think quite mode limits compressor speed but I don't know what it changes it to.  It should modulate down to min when it has to without being on quiet mode.   

 


   
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