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Ecodan - flow rates, sensors, settings

 
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Air Source Heat Pumps (ASHPs)
Last Post by rhh2348 1 month ago
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 Johnmo
(@johnmo)
Prominent Member Member
1654 kWhs
Joined: 2 years ago
Posts: 317
08/08/2024 11:27 am  

Posted by: @derek-m
↑

@johnmo

I think you will find that your results indicate the following.

All control systems have limits within which they can operate correctly, but once you go outside those limits then the control system can no longer perform correctly.

Within your controller it would appear that there are two individual control loops, one varies the compressor speed to produce the required LWT and also supply the thermal energy demand, while the other varies the water pump speed to produce the desired DT.

On start-up the controller senses that the LWT is below the desired value, so runs the compressor faster to produce more thermal energy. As the LWT starts to increase it creates a DT between LWT and RWT, but there will be a limit as to how high the LWT can increase until the RWT also starts to increase. As the LWT and RWT start to warm up, the controller starts to reduce the compressor speed and thermal energy output as it senses that the system is warming up. It would appear that the controller pulled back the compressor to its minimum operating speed.

Because the heat pump is still producing more thermal energy than that being emitted by the heat emitters, the net effect is that the RWT continues to increase, which in turn causes the DT to reduce and the LWT also to increase.

The LWT controller has now reached its minimum operating limit, so can no longer prevent the LWT from increasing. The DT controller has also reached its operating limit and can no longer maintain the DT at 5C, but now appears to be increasing the flow rate to try to prevent the LWT from continuing to increase. This it can do for a limited period of time, but because the heat pump is still producing more thermal energy than is required, the LWT continues to increase until it reaches the high limit and stops the heat pump.

 

That sounds about right. Would have pushing out circa 5kW against a heat demand of about 0.5kW. So floor basically buffering the heat.

 

Maxa i32V5 6kW ASHP (heat and cooling)
6.5kW PV
13.5kW GivEnergy AIO Battery.


   
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 rhh2348
(@rhh2348)
Trusted Member Member
323 kWhs
Joined: 7 months ago
Posts: 34
Topic starter 12/08/2024 6:53 am  

Posted by: @rhh2348
↑
can anyone confirm they have experienced the FTC6 adjusting pump speed to optimise running operation (e.g. slow down flow C increases / increase dT)?
Nudging this thread to see if any other Ecodan can share their experiences of their set up and how it behaves when heating water.

 

Furthermore, does anyone know how a stand-alone [Grundfos UPM3] pump would operate if under PWM control - does it map FTC speed 1 to lowest pump flow and speed 5 to highest and step up and down, or is it more-variable on the l/m??
Likewise, if anyone's got a setup similar to this, would be great to hear from you.

 

Mitsubishi ecodan PUZ-WM60VAA (6kW) with FTC6; third-party cylinder + pumps; LLH


   
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