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.
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.
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.
Hi @rhh2348 , coming late to this thread as our Ecodan is off and our DHW is wet solar during the summer months.
Have you found the answers to your question either via your tests or feedback?
1. there is a fixed flow rate you should be targeting with the Ecodan.
2. As you have a 3rd party cylinder it’s unlikely the FTC6 controller can vary the speed of your grundfos pump. You are left with manually adjusting the 3 speed dial on the grundfos itself.
3. Ecodan has 4 output bands - full load, part load1, part load2 and Minimum. I believe it can also modulate somewhat within each output band.
Regarding flow rate vs deltaT it is More complicated than just DT5. While that might be a good starting point when the heating is known to be in steady demand. The HP will modulate down to DT3 or so when close to set temp and ramp up to 8 or 9 when asked to raise a cold house temperature. This kind of situation can cause unnecessary panic or doubt in the system.
Our 8.5 Ecodan has a target flow rate of 15 lpm but operates at 17 lpm when heating the DHW because the loop resistance is less than the radiator circuit. It all seems fine.
Ecodans do not have an internal circulator pump they rely on an external circulator pump * the main advantage is that you can precisely size the circulator to suit the head/flow/pressure of the house pipework and size.
When we removed our LLH tank we changed the circulator to a 9m head variable speed model which is happy operating at 48 watts at 16lpm.
So let me know where you’re at and if any of this helps.
Not sure but believe the circulation pump speed is modulated to help manage dT. Sitting stationary may not do anything other than fixed speed.
can anyone confirm they have experienced the FTC6 adjusting pump speed to optimise running operation (e.g. slow down flow C increases / increase dT)?
Having read up on the matter since, the Ecodans do not do this - they run at one speed, be that which is set internally on the pump or on the FTC pump speed settings which sends the desired speed to the pump by PWM.
does anyone know how a Grundfos UPM3 would operate if under PWM control - does it map FTC speed 1 to lowest pump flow and speed 5 to highest
It'd still be interesting to know the answer to this - the Grundfos manual shows the following; I'm not clear what it means - particularly in relation to 3 curves + one straight line and the 5 FTC speed settings:
Our 8.5 Ecodan has a target flow rate of 15 lpm but operates at 17 lpm when heating the DHW because the loop resistance is less than the radiator circuit. It all seems fine.
I am assuming you are aware of the FTC(6, I think) pump speed settings that allow you to set a different circulating pump speed for space heating to that of the hot water - I believe it uses PWM to do so.
Our 8.5 Ecodan has a target flow rate of 15 lpm but operates at 17 lpm when heating the DHW because the loop resistance is less than the radiator circuit. It all seems fine.
I am assuming you are aware of the FTC(6, I think) pump speed settings that allow you to set a different circulating pump speed for space heating to that of the hot water - I believe it uses PWM to do so.
I’ve been looking for ways to control flow rates on our ecodan for over 2 years specifically for our Tempest cylinder. We now control our bespoke circulation pump down to a precise flow rate on a dial on the pump which works very effectively.
In the time we’ve looked into it I’m not aware of any differential flow rates on the Ecodan between DHW and domestic heating available on the FTC6 controller settings. So if you have found something we would be very interested in what you’ve found.
Having said that I have a 3rd party cylinder (not Mitsubishi) so I also know that the FTC6 controls for pump speed as supplied to us do not have integrated pwm speed adjustment as we were given to understand that the integrated ecodan electronics does not work with 3rd party pumps and cylinders.
In any case my understanding is that the FTC6 controller could only adjust the pump speed to a fixed output for both DHW and domestic heating. It didn’t have live variable speeds. *I stress that’s my understanding and interpretation of how it’s set up on the FTC6.
However there is a podcast tomorrow at 10.30am by Mitsubishi hosted by this web site. (See adverts ) perhaps there might be room for a question to be asked on that podcast.
It would be great to hear any news or changes on how remote controls might be applied to third party equipment within a commonly installed Ecodan setup.
Our 8.5 Ecodan has a target flow rate of 15 lpm but operates at 17 lpm when heating the DHW because the loop resistance is less than the radiator circuit. It all seems fine.
I am assuming you are aware of the FTC(6, I think) pump speed settings that allow you to set a different circulating pump speed for space heating to that of the hot water - I believe it uses PWM to do so.
I’ve been looking for ways to control flow rates on our ecodan for over 2 years specifically for our Tempest cylinder. We now control our bespoke circulation pump down to a precise flow rate on a dial on the pump which works very effectively.
I may very well come back to you for some detail on that pump at some point in the near future 🙂
In the time we’ve looked into it I’m not aware of any differential flow rates on the Ecodan between DHW and domestic heating available on the FTC6 controller settings. So if you have found something we would be very interested in what you’ve found.
I was referring to this:
Having said that I have a 3rd party cylinder (not Mitsubishi) so I also know that the FTC6 controls for pump speed as supplied to us do not have integrated pwm speed adjustment as we were given to understand that the integrated ecodan electronics does not work with 3rd party pumps and cylinders.
OK, that may be the answer I was looking for, however as the pre-plumbed cylinder comes with a Grundfos UPM3L 25-75 130AZA as primary pump (the L in 3L meaning 'large' according to the Grundfos web site), I would imagine the use of that pump (or a variant) may provide the same functionality, subject to use of/making an appropriate cable...
In any case my understanding is that the FTC6 controller could only adjust the pump speed to a fixed output for both DHW and domestic heating.
See above response.
It didn’t have live variable speeds.
That is correct, as I wrote elsewhere the other day.
However there is a podcast tomorrow at 10.30am by Mitsubishi hosted by this web site.
My bad…. the FTC6 does have separate speed settings as you say. It’s some time since I’ve looked at the on screen menu for pump speeds because we can’t use them with our setup.
however, as I’ve said, this doesn’t work on third party pumps and cylinders. Perhaps there is a bespoke way that Mitsubishi might now be able to offer a modification.
We have a Tempest Solar cylinder which has two coils and has 250l volume. Solar thermal array on the roof. The Grundfos circulation pumps were replaced when we had a low loss header removed. We now have just a single loop circulation pump which does DHW and space heating. Optimum flow rate is 15 lpm (set manually on the dial and operates at 48 to 50 watts) but as stated above this rises to 17 lpm on the DHW cycle but we don’t see any problem with this small rise in flow as we get our target 48c temperature in 30 minutes.
the pump is the Yonos-Pico 25/1-8 article 4215517/23w26/180.
The solar panel, on 11th October is still providing 100% of our DHW needs on a sunny day like yesterday. However output will start to decline on cloudy days in output and just act as a gentle boost to hw temp through winter until mid April.
@rhh2348, here is a chart from yesterday afternoon showing HP operating for space heating while the solar panel is gently heating the DHW.
Let me know if you get any further with using the grundfos pump you mentioned.(Grundfos UPM3L 25-75 130AZA) it sounds plausible as a solution if it can provide enough head pressure for you’re pipe runs.
This post was modified 3 months ago 2 times by SUNandAIR
