Grant aerona 3 ASHP, anyone using one of these. Thoughts?

[JohnMo]

1 hour ago, JamesPa said:

There is a severe danger that the perfect gets in the way of the good, to the advantage of the bad.  If doing it perfectly is too complex most will default to mode 1

Not sure I agree.  A house on an open flowing weather compensation system  is simple.  No actuators, no thermostats, you don't need mixers (in many cases) and in most situations a single pump is used, with the boiler or HP modulating its speed.  You can calculate the heating slope etc, so limited faffing getting things correct.

 

There is a study linked to on here, were 3 situations were tested. Heat pump via buffer, buffer control by on/off thermostat - CoP 2.7.  Test 2 Buffer with HP on weather compensation, CoP around 3.5.  No buffer, open system HP on WC, CoP around 4.2.  All tested at 7 degC outside temp and same simulated building loads.

 

56 minutes ago, JamesPa said:

I wonder what the Germans do, they have had weather compensation on their boilers for decades

So has the UK had WC, but we are too daft to use it.  Plumbers install a boiler on Y plan and flow central heating at the same flow temp as a cylinder.  Then on UFH mix the flow temp down.  We stuff our houses full of on/off thermostats, run a boiler or heat pump way to hot and then wonder why we have gas boilers that run at 80% efficiency, when they are capable and designed to give 110% efficiency.  And ASHP that give a CoP of 3 (if your lucky) when they should be getting over 4-5.

[JamesPa]

19 minutes ago, JohnMo said:

Not sure I agree.  A house on an open flowing weather compensation system  is simple.  No actuators, no thermostats, you don't need mixers (in many cases) and in most situations a single pump is used, with the boiler or HP modulating its speed.  You can calculate the heating slope etc, so limited faffing getting things correct.

In principle I agree with you.  But people are profoundly lazy and uneducated about this stuff, and our government is profoundly stupid (all as you have yourself intimated).  So in the real world things have to be made extremely simple and also deliver the necessary result (a house that is warm without tweaking) otherwise they will be clobbered as you say.  It's not ideal but systems have to be designed for the majority not for those on this forum.  Calculating anything is probably more than we can realistically expect, taking into account individual usage patterns etc is well beyond reasonable expectations in the real world.

 

I think your system setup is likely correct, the question is how installers can tune it without any instructions that are too complex in whatever small number of hours (minutes?) they allocate and more or less guarantee no callbacks.  Today it's too easy to do mode 1, quick, familiar and warm house guaranteed

[LnP]

6 hours ago, JohnMo said:

So what's that?

I didn't know either, but found this ...

https://renewableheatinghub.co.uk/weather-compensation-the-lizzie-curve

[HughF]

31 minutes ago, JamesPa said:

In principle I agree with you.  But people are profoundly lazy and uneducated about this stuff, and our government is profoundly stupid (all as you have yourself intimated).  So in the real world things have to be made extremely simple and also deliver the necessary result (a house that is warm without tweaking) otherwise they will be clobbered as you say.  It's not ideal but systems have to be designed for the majority not for those on this forum.  Calculating anything is probably more than we can realistically expect, taking into account individual usage patterns etc is well beyond reasonable expectations in the real world.

 

I think your system setup is likely correct, the question is how installers can tune it without any instructions that are too complex in whatever small number of hours (minutes?) they allocate and more or less guarantee no callbacks.  Today it's too easy to do mode 1, quick, familiar and warm house guaranteed

Fit homely, tell it target room temperature, homely learns the WC curve that suits the property and emitters. 
 

Makes installers jobs much much easier. 

[JamesPa]

1 hour ago, HughF said:

Fit homely, tell it target room temperature, homely learns the WC curve that suits the property and emitters. 

I agree entirely, this device seems like a game changer for getting WC right.  Its function should be built into every HP controller and installers forced by law to use it.

 

That just leaves balancing.  Balancing the traditional way by matching deltaTs might be a good enough approximation, provided emitters are correctly sized (does balancing present any challenges for installations done in the summer?)

[JohnMo]

 

2 hours ago, JamesPa said:

Its function should be built into every HP controller and installers forced by law to use it.

Pity it's only suitable for a limited selection of heat pumps. But it should be an easy enough algorithm to write I would have thought

[Kevm]

Mitsubishi has something called, 'auto adaptation'.  It's based on WC but uses room temperature as a target using its own thermostat.  No need for expensive add-ons, specialist knowledge or faffing around with WC curves. I'm trying it out at the moment and it seems to work well.   

 

I'm sure other manufacturers have similar technology.  Or do they? 

 

 

[JohnMo]

2 minutes ago, Kevm said:

auto adaptation

Think it's good for radiators but not UFH 

[JamesPa]

1 hour ago, Kevm said:

Mitsubishi has something called, 'auto adaptation'. 

I had always assumed, possibly incorrectly, this was load compensation, adjusting for short term variations due eg to solar gain, rather than targeting a semi permanent change in the WC curve.  One problem with control systems for heating is that there are several different time constants involved.  I'm not clear whether it's 'good enough' to fix one but not the others.

 

It would be good to understand clearly what these marketing terms mean, and how much they matter.  I feel a spreadsheet coming on...

[ReedRichards]

3 hours ago, JamesPa said:

I had always assumed, possibly incorrectly, this was load compensation....

 

I think it probably is Load Compensation but Heat Pump vendors seem extremely reluctant to use the same terminology that is applied to gas boilers.

 

If you are trying to maintain a steady state (and the response time constant is not too long, so radiators probably) then Load Compensation should compensate for inaccurate Weather Compensation settings.

 

What does Homely do that a combination of Weather Compensation and Load Compensation does not?    

[JohnMo]

1 hour ago, ReedRichards said:

What does Homely do that a combination of Weather Compensation and Load Compensation does not

I would think, as they only fit a small selection of heat pumps, analysis of house response to heating inputs and then writing control parameters back to the heat pump controller. Repeat... until it's all calibrated. Then possibly sit there for ever more looking pretty.

[HughF]

Homely is a modbus flow temperature controller, with the smarts (the thermal modelling of your house) and all the flow temperature blocks for the next 24hrs done in software on AWS.

 

You tell it your target room temperature and schedule, it figures out the cheapest way to get there, given the forecast and the spot pricing for your TOU tariff.

 

it takes control of the heat pump, bypassing the built in weather/load compensation. For installers, it gives them a one button commissioning of midea units, as all parameters can be set  over modbus, it means they can run the system in weather comp without needing to ever return and tweak the curve following complaints, and the homeowner gets a simple to use interface.
 

It has an internal temperature sensor, an interface unit and a smartphone app.

Edited January 23, 2023 by HughF

[Kevm]

22 hours ago, JamesPa said:

I had always assumed, possibly incorrectly, this was load compensation, adjusting for short term variations due eg to solar gain, rather than targeting a semi permanent change in the WC curve.  One problem with control systems for heating is that there are several different time constants involved.  I'm not clear whether it's 'good enough' to fix one but not the others.

 

It would be good to understand clearly what these marketing terms mean, and how much they matter.  I feel a spreadsheet coming on...

It's definitely more than that.  It bumps up the flow when the difference between set and actual room temp is a lot.  It does this less when the difference is only a little.  Some of the parameters that control this are adjustable. It also claims to have some 'learning' capability.  It does because it behave differently in the first 2 or 3 days compared with now. 

 

[ReedRichards]

55 minutes ago, Kevm said:

....It bumps up the flow when the difference between set and actual room temp is a lot.  It does this less when the difference is only a little. .. 

 

 

This is exactly the action of Load Compensation.  

[Kevm]

2 hours ago, ReedRichards said:

 

This is exactly the action of Load Compensation.  

 

I never said it wasn't.  My response was to JamesPa, who said "load compensation, adjusting for short term variations due eg to solar gain".  I was just saying that from what I observed it was more than that.

 

Mitsubishi is a bit vague on how it works but on another forum, a member asked their technical support and got an answer. Still a bit short on detail but suggests it's a bit more than weather and load compensation. It's probably not as cheap to run as me constantly tinkering with WC curves but for someone less well informed or interested, it's pretty good.

 

 

Question: -

 

My understanding of how Auto Adaptation should operate is that, the water temperature produced by the heat pump should follow the weather compensation curve, but if the indoor air temperature is below the desired temperature, the Auto Adaptation would add slightly to the weather compensation to gradual increase the water temperature, and hence increase the indoor air temperature. The reverse should occur if the indoor air temperature is too high.

Could you please clarify if my assessment of the control philosophy is correct?

 

Reply:-

 

Good Afternoon,

Yes your description of the Auto adaption mode is quite accurate.

The controller will constantly monitor room temperature and vary the flow temperature depending on the outside ambient temperature and how far away the target temperature is from the actual room temperature.

It also has a self-learning function which will follow similar patterns it adapted to in the past. For example, if 3 days previously the outdoor ambient was 5 degrees and the room stat was set to 22 degrees and the room was at 20 degrees, it will look at the flow temperature it used that day to get the room up to 22 degrees and adapt the flow temperature accordingly. If the room temperature does not increase over a 1 hour period it will increase flow temperature by 1 degree every hour until it reaches room target temperature.

[JamesPa]

1 hour ago, Kevm said:

Yes your description of the Auto adaption mode is quite accurate.

The controller will constantly monitor room temperature and vary the flow temperature depending on the outside ambient temperature and how far away the target temperature is from the actual room temperature.

It also has a self-learning function which will follow similar patterns it adapted to in the past. For example, if 3 days previously the outdoor ambient was 5 degrees and the room stat was set to 22 degrees and the room was at 20 degrees, it will look at the flow temperature it used that day to get the room up to 22 degrees and adapt the flow temperature accordingly. If the room temperature does not increase over a 1 hour period it will increase flow temperature by 1 degree every hour until it reaches room target temperature.

Potentially that sounds pretty damn good provided that

 

a. other forms of control (room stats and TRVs) are set sufficiently above the target temperature that they only kick in in extreme circumstances, and (of course)

b. that in practice, it achieves the correct temperature.  Please let us know if it does

 

The Ecodan is popular on this forum and so understanding it helps.  From a purely selfish point of view its also on my shortlist (of 2), and this feature, if it works well, would help swing it.  It makes me question what the relationship in the Ecodan is between the WC curve and the autoadapt curve.  After a while the former surely becomes irrelevant, or perhaps it always starts with the WC temp then adapts only if it perceives a difference.

 

Autoadapt as described may even be better than a linear WC curve (which is what the Ecodan supports to the best of my knowledge).  The theoretical WC curve (at least for radiators) is not quite linear, because output is not a linear function of the temperature diff between emitter and the room.  If the autoadapt doesn't lead to wild temperature swings and generally hits the spot, then its very probably doing at least as good a job as WC or better.

 

Im working on the spreadsheet I hinted at earlier to model the effect of WC on COP.  Very preliminary results (which use the performance figures from the 11.2kW Ecodan and make no allowance for any loss of efficiency due to cycling) are tending to indicate that more or less any half reasonable WC curve makes about a 20% difference to total fuel consumption, and the differences between the various flavours of half reasonable WC curves is small.  I need to refine the algorithm for calculating COP as a function of ambient and flow temperature however, before I can be confident enough to publish so please take this with a pinch of salt until I do.

 

 

[billt]

7 hours ago, HughF said:

Homely is a modbus flow temperature controller, with the smarts (the thermal modelling of your house) and all the flow temperature blocks for the next 24hrs done in software on AWS.

 

I was considering Homely, but being reliant on the cloud really puts me off.

 

Why do they need to use the cloud except to harvest your data?

[HughF]

32 minutes ago, billt said:

 

I was considering Homely, but being reliant on the cloud really puts me off.

 

Why do they need to use the cloud except to harvest your data?

101x easier to update the algorithms if they run on AWS instead of having to roll out firmware updates to all the installed units in the field. Trust me, I work in embedded electronics…

 

Personally I don’t give 2 hoots what they do with my temperature data.

[JamesPa]

6 minutes ago, HughF said:

101x easier to update the algorithms if they run on AWS instead of having to roll out firmware updates to all the installed units in the field. Trust me, I work in embedded electronics…

 

Easier for the manufacturer is not necessarily better for the customer!  I 100% agree that a central heating system which relies on the cloud for real time operation is not desirable (I would go so far as to say totally unacceptable).  In 10, 20 years time will the 'service' still be provided?

[billt]

37 minutes ago, HughF said:

101x easier to update the algorithms if they run on AWS instead of having to roll out firmware updates to all the installed units in the field. Trust me, I work in embedded electronics…

 

Personally I don’t give 2 hoots what they do with my temperature data.

 

Why should they need to update the firmware? Presumably they got it right in the first place. In my experience many firmware updates in consumer electronics make the functionality worse not better.

 

I understand that they need internet connectivity for TOU tariff data, but that's not necessary for the core functionality, and not something that I would use. No doubt they also scrape outside air temperature from weather stations rather than having a local sensor, but that's sub optimal. (That's what my current heating controller does, but it still operates without an internet connection. Does the Homely?)

[PhilT]

1 hour ago, JamesPa said:

Potentially that sounds pretty damn good provided that

 

a. other forms of control (room stats and TRVs) are set sufficiently above the target temperature that they only kick in in extreme circumstances, and (of course)

b. that in practice, it achieves the correct temperature.  Please let us know if it does

 

The Ecodan is popular on this forum and so understanding it helps.  From a purely selfish point of view its also on my shortlist (of 2), and this feature, if it works well, would help swing it.  It makes me question what the relationship in the Ecodan is between the WC curve and the autoadapt curve.  After a while the former surely becomes irrelevant, or perhaps it always starts with the WC temp then adapts only if it perceives a difference.

 

Autoadapt as described may even be better than a linear WC curve (which is what the Ecodan supports to the best of my knowledge).  The theoretical WC curve (at least for radiators) is not quite linear, because output is not a linear function of the temperature diff between emitter and the room.  If the autoadapt doesn't lead to wild temperature swings and generally hits the spot, then its very probably doing at least as good a job as WC or better.

 

Im working on the spreadsheet I hinted at earlier to model the effect of WC on COP.  Very preliminary results (which use the performance figures from the 11.2kW Ecodan and make no allowance for any loss of efficiency due to cycling) are tending to indicate that more or less any half reasonable WC curve makes about a 20% difference to total fuel consumption, and the differences between the various flavours of half reasonable WC curves is small.  I need to refine the algorithm for calculating COP as a function of ambient and flow temperature however, before I can be confident enough to publish so please take this with a pinch of salt until I do.

 

 

There Is one other feature of Auto Adaptation which marks it out from pure load and/or weather compensation modes. If ambient temps mean heat demand is low, depending on the curve you set, WC mode will allow the flow temp to fall below that which corresponds to minium continuous power delivery, so the comprressor switches off occasionally and you see a cycling effect in the flow temp readout. Auto Adaptation, on the other hand, does not allow the flow temp to fall below that which ensures continuous power delivery, even though you can see the power demand fall as the gap between actual and target temp closes, so the flow temp readout is never interrupted by a compressor pause, presumably for efficiency reasons. The flip side of this is that the target room temp is reached more quickly so in warmer ambient temps the heating will simply be off for longer periods.

Edited January 23, 2023 by PhilT

[Kevm]

2 hours ago, JamesPa said:

Potentially that sounds pretty damn good provided that

 

a. other forms of control (room stats and TRVs) are set sufficiently above the target temperature that they only kick in in extreme circumstances, and (of course)

b. that in practice, it achieves the correct temperature.  Please let us know if it does

 

The Ecodan is popular on this forum and so understanding it helps.  From a purely selfish point of view its also on my shortlist (of 2), and this feature, if it works well, would help swing it.  It makes me question what the relationship in the Ecodan is between the WC curve and the autoadapt curve.  After a while the former surely becomes irrelevant, or perhaps it always starts with the WC temp then adapts only if it perceives a difference.

 

Autoadapt as described may even be better than a linear WC curve (which is what the Ecodan supports to the best of my knowledge).  The theoretical WC curve (at least for radiators) is not quite linear, because output is not a linear function of the temperature diff between emitter and the room.  If the autoadapt doesn't lead to wild temperature swings and generally hits the spot, then its very probably doing at least as good a job as WC or better.

 

Im working on the spreadsheet I hinted at earlier to model the effect of WC on COP.  Very preliminary results (which use the performance figures from the 11.2kW Ecodan and make no allowance for any loss of efficiency due to cycling) are tending to indicate that more or less any half reasonable WC curve makes about a 20% difference to total fuel consumption, and the differences between the various flavours of half reasonable WC curves is small.  I need to refine the algorithm for calculating COP as a function of ambient and flow temperature however, before I can be confident enough to publish so please take this with a pinch of salt until I do.

 

 

 

@JamesPa

It is good at maintaining temperature but it will ramp up the LWT a lot (to 55 deg) to warm a cool house - if you let it.  I'm limiting mine to 48 deg. 

 

I agree about the difference between WC and COP.  I did some crude analysis comparing fixed 45 deg flow with WC and came up with this.  

 

Maybe a new topic to discuss all this might be better as the OP's thread has been hijacked a bit.

 

 

 

 

 

 

 

 

Edited January 23, 2023 by Kevm

[JohnMo]

49 minutes ago, Kevm said:

crude analysis comparing fixed 45 deg flow with WC

Interested - So what inputs did you use to get your data points?

[Post and beam]

3 hours ago, Kevm said:

Maybe a new topic to discuss all this might be better as the OP's thread has been hijacked a bit.

As the OP, i say crack on guys. All discussion of this nature is good as every day is a school day. I am just about to create another post with a question that spins out of this anyway.