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11.2kW Ecodan in 182sqm property

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(@kev-m)
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Posted by: @morgan

@derek-m @markc

Hi Derek and Mark.

I get that but I might not always run via weather compensation so when running via other means my preference is to dispose of the neostat altogether and have all in house Mitsubishi controls and remove the thermostat out of the equation.

I'm going to do the same.  

The Ecodan wireless controller is a thermostat; just one that communicates with the FTCX controller.  The issue with using 3rd party thermostats is that they don't.  This is surely just a data communication and software issue and I'm sure Mitsubishi could make 3rd party thermostats work with auto adaptation if they wanted to.  Is there some sort of communication standard I wonder?  I sure someone clever enough could hack into the FTC.  

I also wonder if other manufacturers have something similar to Mitsubishi's auto adaptation that does work with 3rd party thermostats. 


   
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Morgan
(@morgan)
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@kev-m 

Hi Derek.  Do you have Melcloud up and running within your system?

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.


   
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(@derek-m)
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Posted by: @kev-m
Posted by: @morgan

@derek-m @markc

Hi Derek and Mark.

I get that but I might not always run via weather compensation so when running via other means my preference is to dispose of the neostat altogether and have all in house Mitsubishi controls and remove the thermostat out of the equation.

I'm going to do the same.  

The Ecodan wireless controller is a thermostat; just one that communicates with the FTCX controller.  The issue with using 3rd party thermostats is that they don't.  This is surely just a data communication and software issue and I'm sure Mitsubishi could make 3rd party thermostats work with auto adaptation if they wanted to.  Is there some sort of communication standard I wonder?  I sure someone clever enough could hack into the FTC.  

I also wonder if other manufacturers have something similar to Mitsubishi's auto adaptation that does work with 3rd party thermostats. 

Hi Kev,

I'm afraid that you are not exactly correct. Whilst the remote controller can be used as a thermostat in combination with the main FTC controller, it actual acts as a remote temperature sensor. The thermistor in the remote controller measure the room temperature, and the remote controller transmits this information periodically to the main FTC controller. Along with the information provided by the ambient air temperature thermistor, the FTC controller then calculates the required water flow temperature to heat the room to the desired temperature. By measuring the actual room temperature it is therefore possible for the FTC controller to perform auto adaptation control.

I am not certain if a standard communication protocol has been agreed between the different manufacturers yet.

A wireless thermostat can be connected to the FTC controller, but will only perform on - off control, not auto adaptation control.


   
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(@derek-m)
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Posted by: @morgan

@kev-m 

Hi Derek.  Do you have Melcloud up and running within your system?

I don't have a Mitsubishi, so the answer is no.


   
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Jeff
 Jeff
(@jeff)
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Posted by: @derek-m
Posted by: @kev-m
Posted by: @morgan

@derek-m @markc

Hi Derek and Mark.

I get that but I might not always run via weather compensation so when running via other means my preference is to dispose of the neostat altogether and have all in house Mitsubishi controls and remove the thermostat out of the equation.

I'm going to do the same.  

The Ecodan wireless controller is a thermostat; just one that communicates with the FTCX controller.  The issue with using 3rd party thermostats is that they don't.  This is surely just a data communication and software issue and I'm sure Mitsubishi could make 3rd party thermostats work with auto adaptation if they wanted to.  Is there some sort of communication standard I wonder?  I sure someone clever enough could hack into the FTC.  

I also wonder if other manufacturers have something similar to Mitsubishi's auto adaptation that does work with 3rd party thermostats. 

Hi Kev,

I'm afraid that you are not exactly correct. Whilst the remote controller can be used as a thermostat in combination with the main FTC controller, it actual acts as a remote temperature sensor. The thermistor in the remote controller measure the room temperature, and the remote controller transmits this information periodically to the main FTC controller. Along with the information provided by the ambient air temperature thermistor, the FTC controller then calculates the required water flow temperature to heat the room to the desired temperature. By measuring the actual room temperature it is therefore possible for the FTC controller to perform auto adaptation control.

I am not certain if a standard communication protocol has been agreed between the different manufacturers yet.

A wireless thermostat can be connected to the FTC controller, but will only perform on - off control, not auto adaptation control.

There isn't a single control standard being used at present. 3 standards i have noticed being used by heat pump manufacturers to control them are.

Mobus (e.g. LG) 

ebus (e.g. Valiant) 

OpenTherm (e.g. NIBE) 

There are others i assume. 

So for example there are people using a raspberry pi and OpenTherm to control NIBE heat pumps.

The OpenTherm website lists the manufacturers using it. Some manufacturers don't use it for all their products (e.g. I am not sure Dakin are currently using it for their heat pumps) 

How much you can actually do in terms of control varies by manufacturer, heat pump model and their interpretation of the standard. Some manufacturers appear not to want 3rd party control anywhere near their pumps if possible

Tado controllers have good control of some gas boilers with their weather compensation and flow temperature modulation features so they are one to watch with heat pumps. Am not clear how the TADO integration actually works with individual heat pumps at present even though they mentioned it. 

Homely is another controller that has been mentioned before on the forum which has it's own thermistor, humidity sensor, weather compensation etc. I assume the actual integration with ASHPs varies dramatically by manufacturer. Very little on the website. 

 

 

 

 

 

 


   
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(@derek-m)
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@jeff 

Hi Jeff,

Would that be Modbus, rather than Mobus?


   
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Jeff
 Jeff
(@jeff)
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Posted by: @derek-m

@jeff 

Hi Jeff,

Would that be Modbus, rather than Mobus?

Yes. So much for my proof reading skills... 


   
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(@sand)
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Topic starter  

So Ive set up comp curve as Derek advised but I have a question what do i do with the wall thermostats for UFH do i leave them on manual? If yes at what temp do I leave them on, 21  or go slightly higher, so I can monitor and adjust the curve. Also wasn'nt really clear about the DWH does the curve deal with that too or do I have to set that differently.


   
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(@kev-m)
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@sand 

DHW is set differently from heating/compensation curve so won't be affected. 

If you set your thermostats a couple of degrees above the temperature you want, the room temperature should vary according to the flow temperature.  The thermostats will call for heat all the time unless you 'overshoot', when they will switch the ASHP off until the temperature drops.  Once you've got the weather compensation adjusted then the thermostats should never call for heat.  I just turn mine up to 30C so they are always calling for heat but room temp is quite steady. 

If you run weather compensation and set the thermostats to the temperature you want, the ASHP and thermostats can get into a bit of a conflict and the ASHP can end up turning on and off (cycling) more than it needs to.

 


   
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(@sand)
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Topic starter  

So sorry Kev M I'm finding the whole thing confusing 🤯. So if I turn my thermostats for the ufh up to 30 it will just call for heat all the time is that right. The thermostats can either be programmed on a timer or set to manual. So do I just turn them to manual and whack them u to 30c (Hubby not convinced he thinks Im just scamming him hes a tight ar@e yorkshire man 🤣) I just want my room to be 21 22c. I really struggle to understand the system especially weather comp only had it 6 wks.


   
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(@derek-m)
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Posted by: @sand

So Ive set up comp curve as Derek advised but I have a question what do i do with the wall thermostats for UFH do i leave them on manual? If yes at what temp do I leave them on, 21  or go slightly higher, so I can monitor and adjust the curve. Also wasn'nt really clear about the DWH does the curve deal with that too or do I have to set that differently.

Hi sand,

I'm afraid those are difficult questions to answer, since it very much depends upon how your system has been wired and configured.

I will try to answer the simplest one first. I don't think that the DHW temperature setting is affected by the weather compensation. The DHW temperature should be set at the lowest acceptable value from an overall efficiency point of view, but of course will periodically be heated above 60C during the sanitisation cycle.

Because you have 7 thermostats, used over 2 zones, I will have to make a number of assumptions, which may or may not be correct. Do you know how many thermostats are associated with the UFH and how many with the radiators? Do any of the radiators have TRV's installed?

Let's consider how the upstairs (radiator) zone may be controlled. If one or more thermostats call for heat, I would expect the relevant zone valve to be opened, and the heat pump to be started along with any external water pump. Heated water from the heat pump would flow through the zone valve to the radiators. When all the thermostats are up to temperature, the heat pump and any external water pump would be stopped and the zone valve closed. The above would work, provided that there is sufficient heat energy being transferred from the heat pump to the radiators, to exceed the heat demand and hence raise the room temperature to the desired level. If the water flow temperature or the water flow rate is insufficient, then the rooms would struggle to reach the desired temperature.

The downstairs (UFH) zone, may or may not have some form of mixing valve arrangement, since the water flow temperature required is often lower than that for radiators. As with the upstairs control, if one or more thermostats call for heat, the zone valve would be opened, and the heat pump started along with any external water pump.

ASHP's are most efficient when operating at the lowest water flow temperature that meets the heat demand, which of course may be different for each individual zone. It should also be remembered that the ASHP will supply the DHW and the two zones on a priority basis, so it is necessary to ensure that there is sufficient heat energy available to meet all needs.

To try to answer your question about thermostat settings and weather compensation mode, you could try the following. Increase each thermostat in turn by 1C, and confirm that the relevant room temperature increases to the new value, then set the thermostat back to the previous setting. Note any rooms that struggle to reach the desired temperature when the thermostat setting is increased. If all the rooms pass the test then set the weather compensation offset from 0 to -1 and repeat the above. When you get to the point where some rooms fail to reach the desired temperature, then raise the offset value by 1.

This should provide the correct weather compensation setting at that particular outside air temperature, whilst operating at the lowest water flow temperature. Monitor the system operation over a range of outside air temperatures, and note any rooms that fail to maintain the desired temperature.

Whilst this is not the most ideal, it should allow your complex system to operate utilising the thermostats, but still operate at the lowest water flow temperature as calculated by the weather compensation.

 

 


   
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(@kev-m)
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@sand 

When it's cold outside, it takes more energy to heat your house than when it's warm. One way of supplying more energy is to make the water in the radiators hotter.  That's all weather compensation does.  When it's 0C outside, your radiators/ufh might need to be 40C to heat your house to 21C.  When it's 10C outside, they might only need to be 35C.  And so on, for other temperatures. Running your ASHP on weather compensation just varies the radiator/ufh temperature depending on the outside temperature.  The only slight problem is that it can take a little bit of tinkering to get the compensation curve right for your house. 

ASHPs are most efficient when running steadily, at lower radiator temperatures.  Running on weather compensation as discussed is more likely to achieve this.  The downside not normally mentioned is that the ASHP will probably be running for longer than if you let the thermostats switch it on and off.  But that is normally compensated for by the increased efficiency.

We find that running the ASHP like we do makes the house temperature more constant and generally more pleasant to live with. As you imply, it's quite a leap of faith to turn the thermostats up and leave the heating on all the time.  

This post was modified 2 years ago by Kev M

   
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