Ecodan - room temp auto adaptation and multiple zones

[BEJB]

I have a 14kW Mitsubishi Ecodan, which heats 2 zones (zone 1 = house with rads and zone 2 = kitchen with UFH) and DHW.

I spent a good time playing with weather compensation only to find that room temperature with auto adaptation heats better with a higher COP - happy bunny!

However, there does seem to be a slight issue. Auto adaptation seems to set itself to the lowest flow temperature to match heat input to heat output. So zone 1 heats well and is very efficient. But the system doesn't run zone 1 and zone 2 at the same time - zone 1 takes precedent if it calls for heat. So zone 1 seems to be on all the time (nice and snug!) and zone 2 seems to be off most/all of the time (a bit chilly). 

Does anyone have any suggestions as to how I might be able to get some heat to zone 2, while still being able to benefit from auto adaptation?

Thanks in advance for any help or advice you can give.

[JohnMo]

1 hour ago, BEJB said:

Auto adaptation

You are aware that auto adaptation isn't for use with UFH? Only works with radiator systems. Think the issue with UFH is the inertia is to large and throws the auto learning out.

 

UFH is very slow, so would really benefit being the lead.

[PhilT]

When i spoke to a Mitsubishi tech about auto with ufh, he said it wasn't so much that it doesn't work, but rather it's an unknown quantity because they have no user data experience, and the software could take much longer to "learn" how your room temperature reacts to changes in heat input, you would need to leave it in a steady state 24/7, eg target room temp at 20degC all the time, until it settles. Do you have separate Ecodan remote controllers for each zone?

Edited December 8 by PhilT

[BEJB]

2 hours ago, PhilT said:

When i spoke to a Mitsubishi tech about auto with ufh, he said it wasn't so much that it doesn't work, but rather it's an unknown quantity because they have no user data experience, and the software could take much longer to "learn" how your room temperature reacts to changes in heat input, you would need to leave it in a steady state 24/7, eg target room temp at 20degC all the time, until it settles. Do you have separate Ecodan remote controllers for each zone?

That's interesting. Yes, I do have separate Ecodan remote controllers for each zone. 

 

Although I have 'set back differentials' for both zones (reduced thermostat overnight), I have less for the UFH and the UFH starts earlier, so it gets a boost first thing in the morning. I could have a go at further reducing or removing the setback differential for zone 2 and raising it even earlier (if there is still a setback differential). 

 

I'd still have the thing where zone 1 wants to just run continuously during the day, rather than heating the house so zone 2 gets a chance. But maybe getting heat overnight would be ok.

 

I do wonder if the auto adaptation can 'learn' the heating of the two different zones - or if it pretends its just one zone and produces a sort of 'average' which is not right for either.

 

I also think there is a design flaw, in that the two zones have very different capacities. Zone 1 has lots of rads and the heat pump has obviously been sized for that. I think the heat pump is therefore oversized for the comparatively small volume of the kitchen UFH. So it can sometimes have comparatively inefficient sawtoothing. This seems less of a problem with auto adaptation than it does with weather compensation, so maybe the auto adaptation does learn something.

 

Thanks for your replies and ideas.

[PhilT]

14 minutes ago, BEJB said:

I do wonder if the auto adaptation can 'learn' the heating of the two different zones - or if it pretends its just one zone and produces a sort of 'average' which is not right for either.

In theory it can but with UFH in a kitchen zone, that's a huge (perhaps impossible) challenge of "learning" in a constantly fluctuating temperature environment, with all manner of appliances going on and off, warm bodies going in and out, sun coming through windows periodically, etc, and how isolated is the kitchen from the rest of the house - possibly different temperature air is wafting in and out? Have a go with the kitchen zone set to WC mode and see what happens.

[BEJB]

I can't set different heating modes for the two zones. I set it for zone 1 and the same applies to zone 2. Room seems to be the best compromise.

I don't know if this is just the way it is setup, or if I could change this to allow different heating modes for different zones.

[PhilT]

15 minutes ago, BEJB said:

I can't set different heating modes for the two zones. I set it for zone 1 and the same applies to zone 2. Room seems to be the best compromise.

I don't know if this is just the way it is setup, or if I could change this to allow different heating modes for different zones.

I can see this screen in the Melcloud app which suggests that you can set the mode by zone, but  I only have one zone so I could be mistaken

[sharpener]

Sounds like this might be a rare case for 3rd party controls, how about

• Optimise for Zone 1 as above which will be correct for rads but too hot for the kitchen UFH
• disconnect/disable Zone 2 controls on Ecodan
• turn down flow rate through kitchen UFH loop(s) until it (almost) requires the same flow temp
• fit 3rd party thermostat in kitchen to control the actuator(s) and take account of cooking gain etc

@JohnMo will be able to tell us if this could work.

 

[JohnMo]

Above sounds about right. Depending on thickness of screed you would need to fiddle with thermostat hysterisis. So get one that can go as low as 0.1 degs hysterisis.  Then if your overshooting, undershooting, you can correct with hysterisis.  Trying to run two systems with very differing inertia isn't easy. You either accept one is always wrong or put a controller to limit it.

[BEJB]

2 hours ago, PhilT said:

I can see this screen in the Melcloud app which suggests that you can set the mode by zone, but  I only have one zone so I could be mistaken

I have the two zones but only one option 

[BEJB]

When I first got the house , the kitchen/utility had third party controls. Dividing the UFH into 2 definitely meant the loops were too small for the ashp to heat!

Anyway, I swapped that out for an ecodan thermostat,which controlled both ufh loops and so worked a bit better. It also showed the temperatures on the Melcloud reports.

I do wonder if there is a setting or a dip switch that allows me to control the heating modes for both zones ....

Edited December 8 by BEJB

[PhilT]

38 minutes ago, BEJB said:

When I first got the house , the kitchen/utility had third party controls. Dividing the UFH into 2 definitely meant the loops were too small for the ashp to heat!

Anyway, I swapped that out for an ecodan thermostat,which controlled both ufh loops and so worked a bit better. It also showed the temperatures on the Melcloud reports.

I do wonder if there is a setting or a dip switch that allows me to control the heating modes for both zones ....

Give Ecodan home owner tech support a call. They have always been very helpful for me

[BEJB]

3 hours ago, PhilT said:

In theory it can but with UFH in a kitchen zone, that's a huge (perhaps impossible) challenge of "learning" in a constantly fluctuating temperature environment, with all manner of appliances going on and off, warm bodies going in and out, sun coming through windows periodically, etc, and how isolated is the kitchen from the rest of the house - possibly different temperature air is wafting in and out? Have a go with the kitchen zone set to WC mode and see what happens.

I think this is very true. I find it difficult to see how the auto adaptation can learn for the kitchen. It does have oven & hob, plus heat from things like the dishwasher etc. Also, it has several windows that face south-east, so gets quite a lot of solar gain. It can be quite cold outside, but if it's sunny it can be quite warm in the kitchen. 

While I think auto adaptation is good for zone 1, if I could set zone 2 to WC, that would definitely be worth a go.

[Gary68]

Are you saying that you can only heat zone 1 or zone 2 at once, or is just that you haven't got the thermostats calling for heat at the same time?

If its the former then something have been wired up incorrectly.

 

I have UFH downstairs and rads upstairs they are on separate stats and both can call for heat independently or together they just have different pumps for each circuit.

 

 

[BEJB]

1 hour ago, Gary68 said:

Are you saying that you can only heat zone 1 or zone 2 at once, or is just that you haven't got the thermostats calling for heat at the same time?

If its the former then something have been wired up incorrectly.

 

I have UFH downstairs and rads upstairs they are on separate stats and both can call for heat independently or together they just have different pumps for each circuit.

 

 

Mmmm- that is interesting. The heating system can heat zone1, zone 2 or DHW but only one of them at a time. I know DHW claims priority, but if I could have zone 1 and zone 2 independently or together, that would probably help. Thanks for the tip - that's something to look at.

 

Interestingly, if I have either zone 1 or zone 2 calling for heat, the Melcloud app shows both of them operating. I always assumed that was an artefact of the software, but maybe it is another thing pointing to some sort of configuration error.

[Gary68]

19 hours ago, BEJB said:

Interestingly, if I have either zone 1 or zone 2 calling for heat, the Melcloud app shows both of them operating. I always assumed that was an artefact of the software, but maybe it is another thing pointing to some sort of configuration error.

 

Mine does that too, I think its just the app.

 

Do you have a mitsubishi preplumbed cylinder, if it was for 2 zones there should be 4 pumps in total, 1 for the primary circuit, 1 for each zone and 1 for dhw.

 

If you turn both stats on to call for heat you should have 2 pumps lit up with lights if they are the std grundfos pumps that are usually on the cylinder