Vaillant ASHP Subpar CoP Investigation Help.

[suspicious_squirrel]

Foreword

 

Hi, a new account here. I feel slightly bad about pitching up and asking for help immediately, but so many of my searches for trying to problem solve for myself end up here. It’s the most knowledgeable place I’ve found so I thought it best.

 

This post has got rather sprawling so I’ve added headings.

 

Introduction

 

I had an ASHP fitted mid September and I’ve not been seeing anything like the CoP I expected after putting everything into heatpunk (4.36 CoP @ 35°C flow) and going off experiences shared on youtube.

 

The set up is a Vaillant Arotherm 7 heat pump feeding the house with a surveyed heat loss of 6.73kW at -2.2°C. The heating is run on an open circuit with our bedroom TRV set to 3 (~20°C) to avoid it overheating at night. The desired temperature is set at 20°C (but set to run in pure weather compensation at 0.5) 

There is a volumiser on the return and no secondary pump.

 

In my mind this would give the ASHP the best chance of running efficiently even if it used more power to maintain heat overnight rather than ramping up in the morning.

 

Looking at my efficiency and comparing it to others, it feels like it should be 1/100% higher than the ~3 I’m seeing now we’re just getting into the heating season.

 

My first assumption was our heating circuit must be causing the issue, it’s a retrofit for a gas boiler with some pipe runs I can’t trace. Everything I researched (largely from these forums) and then checked appears to be ok though:

The flow rate gets to 1207 l/h (20 L/min).

The flow and return to heat pump delta is around 3.3°C (measured using a couple of cheap digital thermometers with probes placed 190 cm from the heatpump in/out as the pipe runs).

 

Request

I’m now out of ideas, and I thought it best to talk to people who know more than me. 

Is this normal; am I missing some wider context as to why my efficiency isn’t great; have I messed up the setting; is there something else to check?
 

I’ve listed below some example CoPs from the Vaillant app and also typed out all the (relevant) settings from the thermostat unit. If anything else would be useful I can sort that too.

 

CoP from Vaillant App

 

Low demand:

Heating: CoP of 2 at 17°C outside temperature (total energy consumption 0.568 KWh)

DHW: CoP of 3.2 at ~15°C during cycle outside temperature (total energy consumption 0.94 KWh)

 

7th Oct:

Heating: CoP of 3.4 at 14°C outside temperature (total energy consumption 3.2 KWh)

DHW: CoP of 3.1 at 11.4-12°C during cycle (total energy consumption 1.3 KWh)

 

12th Oct:

Heating: CoP of 2.9 at 10.4°C outside temperature (total energy consumption 6.4 KWh)

DHW: CoP of 2.6 at 8.3-8.7°C outside temperature (total energy consumption 1.1 KWh)

 

October Overall:

Heating: CoP of 3.2 at 11.3°C outside temperature (total energy consumption 158 KWh, total Heat Generated 507.0KWh)

DHW: CoP of 2.9 at 11.3°C outside temperature (total energy consumption 50.8 KWh, total heat generated 147KWh)

 

For comparison a youtube video with the same ASHP from someone local (ish) had heating CoP of 4.6, at a total heat generated of 507.8KWh (shockingly close to my total heat demand) in October. From memory they run a setback temperature of 18°C overnight and have the heat curve set to 0.60 (upsidedownfork)

 

Heat Pump Settings on thermostat unit.

 

Installation configuration

Installation

Water pressure: 1.2 bar

eBUS compontnets [Not imporatant?]

Adaptive heat curve: Deactivated

Current room air humidity: 51% rel

Hybrid manager: Bival. Point

Heating bivalence point: -25 °C

DHW bivalence pont: -20 °C

Heating alternative point: Off

DHW alternative point: Off

LHM temperature: 25 °C

ESCO: Cooling off

ESCO contact status: Blocked

Back-up boiler: Off

Buffer cylinder offset: 10K

Max. pre-heatng time: Off

OT constant heating: Off

Flow temp. Corr. max. Value: 0K

Basic system diagram config

Basc system diagram code : 8 [DETAILS]

HP control module configuration

MO 2: Not connected

MI: Not connected

Heat Pump 1

Status Heating

Current flow temperature: 26 °C

HP Control Module

Status: Off

Circuit 1 [Set in the app to 20°C all the time (bedroom TRV set to 3 to stop overheating) in manual Operation]

Circuit type: Heating

Status: Heating

Target flow temperature: 29 °C

OT switch-off threshold: 18 °C

Heat curve: 0.50/0.55 (0.5 was a little cool)

Min. Target flow temperature: 20 °C

Max. Target flow temperature: 45 °C

Set-back mode: Normal

Room temp. Mod.: Inactive

Cooling possible: No

Pump status: On

DHW [Set via the app to charge every night from 3-5:30 to 42°C]

Cylinder: Active

Target flow temperature: 0 °C

Cylinder charging pump: Off

Circulation pump: On

Anti-lego. day: Friday

Anti-legio. Time: 02:00

Cylinder charging hysteresis: 7.0 K

Cylinder charging offset: 10 K

Max. cyl. Charging time: 90 min

Cly. charg. Anti-cycle. Tme: 60 min

Parallel cylinder charging: No

 

Noise reduction mode

[Empty schedule]

 

Thanks in advance for any suggestions you have, at an extra cost of about 10 quid in October compared to if I had the same CoP as Mr Fork,  it's not the end of the world, it is annoying not understanding why though.

 

[JohnMo]

Put your cylinder on a timed mode, heat once per day extend to twice if you are running out of water. 

 

Do you need legionella? Do a risk assessment, unless you have a massive cylinder and very little hot water usage, keep water below 45 degs or are old and have medical issues, generally not needed.

 

Couple things I have seen while monitoring.

 

I can get a CoP while running of around 5 to 6, but with long off periods this can drop to about 3 to 4 over the whole day. To get a good CoP you need the heat pump ticking away all the time or cycles of about 10 mins on, 10 mins off.

 

The better insulated the property the harder it becomes to get a great CoP, leaky houses do best it seems.

 

We are running WC last run has just finished and it was 20 mins long, previous run was 3 hrs ago and it 6 degs outside. Run time got a CoP of 5.6, but overall the CoP between the two runs is 3.8. standby cost starting to influence running costs

[JamesPa]

50 minutes ago, JohnMo said:

The better insulated the property the harder it becomes to get a great CoP, leaky houses do best it seems.

 

We are running WC last run has just finished and it was 20 mins long, previous run was 3 hrs ago and it 6 degs outside. Run time got a CoP of 5.6, but overall the CoP between the two runs is 3.8. standby cost starting to influence running costs

That's an interesting observation.  Looking at OPs figures eg 12Oct total energy consumption 6kWh, which is only just over 250W.  7th Oct was half that.  At this level water pumps, control electronics, trace heaters etc all start to matter.  Looked at this way its not surprising that high loss houses get better COP, at least when it's mild.

 

I guess the supplementary question is, how much does it matter.  If your house is warm for 250W input that's a good result in many ways, perhaps there is a point where chasing COP becomes a bit academic.  The better approach might be to look elsewhere to reduce the electricity baseload (which is typically ~250-400W).  This will push up heat pump load but at a cop of 3+ rather than 1 (I'm assuming that all or most electricity consumed in the house eventually appears as heat, which I would think is highly likely).

[JamesPa]

One thing to add to the above.  If your heating load at OAT 10 is  only 750W, then your house loss at -2C is nowhere near the 8kW+ that the Vaillant 7 is capable of at -2/45C.  Probably more like 3-4kW.  You could very likely have got away with the next size down.  This might  have given a bit better COP at mild OAT.  However with an electricity consumption of only 250W the other factors would still be significant, so perhaps not!

[PhilT]

2 hours ago, suspicious_squirrel said:

 

Adaptive heat curve: Deactivated

Are you able to activate? This mode is designed to operate the compressor in the most efficient way possible given flow, outdoor and indoor temps.

[Beelbeebub]

This may be a case of not seeing the overall efficency wood for the (CoP) trees. 

 

At these mild temps the parasitic losses of the system (controls, valves, pumps) will be significant in comparison to the useful heat produced. 

 

October used around 200kwh for heat and DHW, which is about 275w continuously. That's a pretty low consumption given your standby consumption is likely to be in the 100w range. 

 

Maybe, in mild weather, some sort of scheduling where you turn the thing off might yield better results, but your finial gains are likely to be negligible. 

 

 

[JohnMo]

3 hours ago, suspicious_squirrel said:

DHW: CoP of 2.6 at 8.3-8.7°C outside temperature (total energy consumption 1.1 KWh)

You may benefit from running DHW on economy /silent mode, which ever gets the running the lowest output.  The lower the output, the longer the heating time. This in turn means lower flow temp for longer and gets better CoP.

 

3 hours ago, suspicious_squirrel said:

house with a surveyed heat loss of 6.73kW at -2.2°C

Would strongly suspect your heat loss is about 1/3 of that or less. 

[suspicious_squirrel]

Wow, thank you all for the feedback!

 

2 hours ago, JohnMo said:

Put your cylinder on a timed mode, heat once per day extend to twice if you are running out of water. 

 

Do you need legionella? Do a risk assessment, unless you have a massive cylinder and very little hot water usage, keep water below 45 degs or are old and have medical issues, generally not needed.

 

The DHW tank is 300L and only heated once a day (overnight) to 41°C. The turnover is fairly high because of this, but I'm happy with the once a week legionella cycle just in case everything hasn't been cycled out sufficiently, it does lower the CoP of the DHW by 0.8 on the day it runs though.

 

1 hour ago, JamesPa said:

That's an interesting observation.  Looking at OPs figures eg 12Oct total energy consumption 6kWh, which is only just over 250W.  7th Oct was half that.  At this level water pumps, control electronics, trace heaters etc all start to matter.  Looked at this way its not surprising that high loss houses get better COP, at least when it's mild.

 

I guess the supplementary question is, how much does it matter.  If your house is warm for 250W input that's a good result in many ways, perhaps there is a point where chasing COP becomes a bit academic.  The better approach might be to look elsewhere to reduce the electricity baseload (which is typically ~250-400W).  This will push up heat pump load but at a cop of 3+ rather than 1 (I'm assuming that all or most electricity consumed in the house eventually appears as heat, which I would think is highly likely).

 

Yes, I probably have this worse than most since there are no external/supplemental pumps so nothing is hidden from the Vaillant app.

I agree with your sentiment, my only concern is that the CoP suffers more as the weather gets colder, I'll be able to gather more data as we get into winter.

 

 

56 minutes ago, JamesPa said:

One thing to add to the above.  If your heating load at OAT 10 is  only 750W, then your house loss at -2C is nowhere near the 8kW+ that the Vaillant 7 is capable of at -2/45C.  Probably more like 3-4kW.  You could very likely have got away with the next size down.  This might  have given a bit better COP at mild OAT.  However with an electricity consumption of only 250W the other factors would still be significant, so perhaps not!

 

I absolutely could have, unfortunately the air changes per hour used in the calculations are non negotiable which inflated the heat loss. My more realistic heat loss is 5KW when you reduce the air changes per hour.

 

 

41 minutes ago, PhilT said:

Are you able to activate? This mode is designed to operate the compressor in the most efficient way possible given flow, outdoor and indoor temps.

 

Done, I'll report back. It often feels like the ASHP is on for a shorter time than it could be (running hotter than necessary), I assumed this was due to its minimum output though.

 

39 minutes ago, Beelbeebub said:

This may be a case of not seeing the overall efficency wood for the (CoP) trees. 

 

At these mild temps the parasitic losses of the system (controls, valves, pumps) will be significant in comparison to the useful heat produced. 

 

October used around 200kwh for heat and DHW, which is about 275w continuously. That's a pretty low consumption given your standby consumption is likely to be in the 100w range. 

 

Maybe, in mild weather, some sort of scheduling where you turn the thing off might yield better results, but your finial gains are likely to be negligible. 

 

 

 

That’s reassuring, thank you. As mentioned I don’t have any external pumps so that is harming my CoP while likely leading to overall power usage.
I’m not too worried about gaming it, I was concerned the system was running poorly and this would get worse as the temperature drops.

 

Just now, JohnMo said:

You may benefit from running DHW on economy /silent mode, which ever gets the running the lowest output.  The lower the output, the longer the heating time. This in turn means lower flow temp for longer and gets better CoP.

 

Would strongly suspect your heat loss is about 1/3 of that or less. 

 

I'll see what effect the heat curve setting has then change these too. The information for the DHW was more to help provide context to the heating CoP. I could probably improve the DHW CoP by running it at midday, but it’d be madness to not use the overnight rate.

 

Yes, the heat loss is certainly lower, unfortunately we had to use the set figures for air changes in our heatloss.

 

 

 

[Andehh]

Just checked our Cop and it's 3.1 over the whole year. We do two cylinder heats a day to 51 degrees and in summer can smash 4 full tanks on a warm weekend day with filling paddling pools.

 

Still only averaged out to be £160 a month,inclusive of daily washing machine and dishwasher usage. Couple of tumble drys a week,mostly WFH.

 

[sharpener]

I would suggest a few more things based on limited (so far) experience with a 12kW Arotherm Plus.

• Especially as your bedroom tends towards being too warm at night I would suggest using a scheduled setback at night to 18C. You might see a slightly worse CoP but the total energy consumption could still be less. If that works you might even try Eco (= off at night). With such a small heat loss and a relatively powerful HP it should have no trouble in bringing the temp back up in the mornings.
• This will also reduce the parasitic losses. But they are not very big in any case, mine reports just 11W in idle mode (controls are a few W in addition I think).
• Setting Adaptive = on and Room Temp Mod = Extended may make marginal improvements
• The HW algorithm is a bit weird, you could try reducing the cylinder offset to zero. It may not make much difference.
• Make sure the HW is set to Eco on the Heat Pump Interface Unit (not the SensoComfort), this will reduce the peak flow temp and so improve the CoP, You might then need a longer heatup time than 90 min as you have a big tank, or split it into two periods depending on yr tariff.
• I strongly suggest reconsidering the legionella cycle, it seems to be making quite a big hit, for most ppl it is not necessary, there is a useful article on the Heat Geek w/s.
• You have got (HW) Circulation pump = On. Not clear why this is, as MO2 is Not Connected. If you do have a secondary circulation pump you can give it its own schedule so it is only on when it is useful. If you haven't then this setting is not meaningful anyway.

[suspicious_squirrel]

On 10/11/2024 at 18:04, Andehh said:

Just checked our Cop and it's 3.1 over the whole year. We do two cylinder heats a day to 51 degrees and in summer can smash 4 full tanks on a warm weekend day with filling paddling pools.

 

Still only averaged out to be £160 a month,inclusive of daily washing machine and dishwasher usage. Couple of tumble drys a week,mostly WFH.

 

Cheers, do you know what your heat curve is set to?

 

On 10/11/2024 at 21:30, sharpener said:

I would suggest a few more things based on limited (so far) experience with a 12kW Arotherm Plus.

• Especially as your bedroom tends towards being too warm at night I would suggest using a scheduled setback at night to 18C. You might see a slightly worse CoP but the total energy consumption could still be less. If that works you might even try Eco (= off at night). With such a small heat loss and a relatively powerful HP it should have no trouble in bringing the temp back up in the mornings.
• This will also reduce the parasitic losses. But they are not very big in any case, mine reports just 11W in idle mode (controls are a few W in addition I think).
• Setting Adaptive = on and Room Temp Mod = Extended may make marginal improvements
• The HW algorithm is a bit weird, you could try reducing the cylinder offset to zero. It may not make much difference.
• Make sure the HW is set to Eco on the Heat Pump Interface Unit (not the SensoComfort), this will reduce the peak flow temp and so improve the CoP, You might then need a longer heatup time than 90 min as you have a big tank, or split it into two periods depending on yr tariff.
• I strongly suggest reconsidering the legionella cycle, it seems to be making quite a big hit, for most ppl it is not necessary, there is a useful article on the Heat Geek w/s.
• You have got (HW) Circulation pump = On. Not clear why this is, as MO2 is Not Connected. If you do have a secondary circulation pump you can give it its own schedule so it is only on when it is useful. If you haven't then this setting is not meaningful anyway.

I gave the overnight running a lot of thought, if we used the setback we'd maybe save off peak rate use in the evening, but then in the morning have the house ramping back up just after the cheap rate ends. I don't think there'd be much in it, but the current system feels like the most cost effective and comfortable.

 

The adaptive and Room Mod moves me off pure weather compensation and relies on the indoor units thermostat doesn't it? I thought pure weather comp is normally best if you can get the curve dialed in.

 

I'll have a look at the DHW stuff next, with the overnight tarrif even at a CoP of 1 it'd beat gas.

 

I'll switch that off, could you tell me what "MO 2" is?  No secondary pump, which I assume dosen't help my CoP since I assume the 50w (?) is being accounted for when with an external unit it'd be hidden.

 

 

So a few of just having changed "Adaptive heat curve" to activated and I've had the follow results:

 

11th Nov

Heating: CoP of 3 at 10.2°C outside temperature (total energy consumption 8.4 KWh)
DHW: CoP of 3.5 at 12-12.3°C outside temperature (total energy consumption 1.7 KWh) (it was warmer at 3am than during the day)

 

12th Nov

Heating: CoP of 2.8 at 8.7°C outside temperature (total energy consumption 9.5 KWh)
DHW: CoP of 2.8 at 6°C outside temperature (total energy consumption 1.7 KWh)

 

13th Nov

Heating: CoP of 3 at 8.9°C outside temperature (total energy consumption 9.7 KWh)
DHW: CoP of 2.9 at 9-9.3°C outside temperature (total energy consumption 1.4 KWh) (another warm 3am)

 

 

It sounds like there isn't anything drastically wrong with my settings. With the DHW CoP so close to the central heating, should I be looking at improving my pipework for the central heating?

For the moment I've upped my heat curve to try and get the ASHP to run a bit harder to see if that helps things. - This is only temporary and I'll lower it back down.

 

 

 

[suspicious_squirrel]

Just an additional thought, is there a way to monitor the ahsp run time? It seems to prefer to run hotter rather than longer. It’s hard to confirm this though since despite the assurances from the tabloids, I can’t hear when it’s running despite being sat about 2m away (inside)

[sharpener]

50 minutes ago, suspicious_squirrel said:

just after the cheap rate ends

 

What time is that? Most E7 tariffs are cheap until 0700, same for Cosy.

 

52 minutes ago, suspicious_squirrel said:

I thought pure weather comp is normally best if you can get the curve dialed in

 

If (only if) your sensocomfort is it a suitable place then active or extended can work out better esp. if you have solar gain or other internal heat sources. Adaptive will subsequently keep it tuned to the right curve. More peace of mind than any big further improvement.

 

56 minutes ago, suspicious_squirrel said:

I'll switch that off, could you tell me what "MO 2" is?  No secondary pump, which I assume dosen't help my CoP since I assume the 50w (?) is being accounted for when with an external unit it'd be hidden.

 

MO2 is a mulitfunction 230V output on the Appliance Interface for various kinds of external pump, if you don't have one set it to Not Connected in Installer settings.

 

1 hour ago, suspicious_squirrel said:

For the moment I've upped my heat curve to try and get the ASHP to run a bit harder to see if that helps things.

 

I doubt it will. Adaptive will eventually settle on the optimal heat curve.

 

16 minutes ago, suspicious_squirrel said:

Just an additional thought, is there a way to monitor the ahsp run time?

 

Is displayed on the App. Also on the VWZ AI (not the sensocomfort). You can see the no. of starts as well, if less that 3x the hours run (i.e. avg of 3 starts/hr or less) nothing to worry about, take up macrame instead.

 

[suspicious_squirrel]

2 hours ago, sharpener said:

 

What time is that? Most E7 tariffs are cheap until 0700, same for Cosy.

 

If (only if) your sensocomfort is it a suitable place then active or extended can work out better esp. if you have solar gain or other internal heat sources. Adaptive will subsequently keep it tuned to the right curve. More peace of mind than any big further improvement.

 

 

MO2 is a mulitfunction 230V output on the Appliance Interface for various kinds of external pump, if you don't have one set it to Not Connected in Installer settings.

 

 

I doubt it will. Adaptive will eventually settle on the optimal heat curve.

 

 

Is displayed on the App. Also on the VWZ AI (not the sensocomfort). You can see the no. of starts as well, if less that 3x the hours run (i.e. avg of 3 starts/hr or less) nothing to worry about, take up macrame instead.

 

 

Intelligent octopus Go, 23:30 - 5:30.

Ah, my sensocomfort is wall mounted next to a 3d printer so sometimes it's the perfect spot, other times not so much. (it's on command strips so I can move it)

When I navigate to the "circulation pump: on" I'm unable to change its state (no option to open it)

Ah yes, run time 533h with 835 on/off cycles, so about 40 min cycles. I'll put a pin in macrame, but that garden is looking scruffy.

[Lofty718]

Adaptive is the least efficienct setting, followed by active. The most efficient is using pure weather compensation but I run mine on active because things like cooking and solar gain can sometimes make the house overheat on pure weather comp

[Andehh]

5 hours ago, suspicious_squirrel said:

Cheers, do you know what your heat curve is set to?

 

I gave the overnight running a lot of thought, if we used the setback we'd maybe save off peak rate use in the evening, but then in the morning have the house ramping back up just after the cheap rate ends. I don't think there'd be much in it, but the current system feels like the most cost effective and comfortable.

 

The adaptive and Room Mod moves me off pure weather compensation and relies on the indoor units thermostat doesn't it? I thought pure weather comp is normally best if you can get the curve dialed in.

 

I'll have a look at the DHW stuff next, with the overnight tarrif even at a CoP of 1 it'd beat gas.

 

I'll switch that off, could you tell me what "MO 2" is?  No secondary pump, which I assume dosen't help my CoP since I assume the 50w (?) is being accounted for when with an external unit it'd be hidden.

 

 

So a few of just having changed "Adaptive heat curve" to activated and I've had the follow results:

 

11th Nov

Heating: CoP of 3 at 10.2°C outside temperature (total energy consumption 8.4 KWh)
DHW: CoP of 3.5 at 12-12.3°C outside temperature (total energy consumption 1.7 KWh) (it was warmer at 3am than during the day)

 

12th Nov

Heating: CoP of 2.8 at 8.7°C outside temperature (total energy consumption 9.5 KWh)
DHW: CoP of 2.8 at 6°C outside temperature (total energy consumption 1.7 KWh)

 

13th Nov

Heating: CoP of 3 at 8.9°C outside temperature (total energy consumption 9.7 KWh)
DHW: CoP of 2.9 at 9-9.3°C outside temperature (total energy consumption 1.4 KWh) (another warm 3am)

 

 

It sounds like there isn't anything drastically wrong with my settings. With the DHW CoP so close to the central heating, should I be looking at improving my pipework for the central heating?

For the moment I've upped my heat curve to try and get the ASHP to run a bit harder to see if that helps things. - This is only temporary and I'll lower it back down.

 

 

 

 

 

Yikes... I think we're 15deg and 3degrees? Does that make sense as a weather comp mode?

[sharpener]

5 hours ago, suspicious_squirrel said:

When I navigate to the "circulation pump: on" I'm unable to change its state (no option to open it)

 

You are just reading its state from an info field in the DHW settings. To change it to Not Connected go to Installation config|Heat pump control module config|MO2.

 

See the simulator here https://simulator.vaillant.com/vrc720/at/#/simulator.

 

4 hours ago, Lofty718 said:

Adaptive is the least efficienct setting

 

Don't agree with that. What evidence do you have for it?

[PhilT]

4 hours ago, Lofty718 said:

things like cooking and solar gain can sometimes make the house overheat on pure weather comp

that's precisely why adaptive is more efficient

[SuperJohnG]

I've not read it all (but I will)

 

We have a 7kW Vailliant arotherm,West of Scotland temps (so mildish). 

 

5.1 CoP on heating (which I was surprised too see the other day)

3.7 on DHW. Which is set to 52 degrees and reheats straight away. 

 

On curve 0.6. One zone, no buffer straight off WC. 

 

Works like a dream literally not touched since we moved in May 2023. 

[Lofty718]

Adaptive is not the most efficient, when I have it turned on it has the curve higher than I would set it manually and tends to overheat the house

 

Adaptive only works on the 'EXPANDED' mode which does not utilize weather compensation and low and slow heating, on expanded mode the heat pump will cycle more as once the heating demand is satisfied it will turn the heat pump off rather than the other modes that keep the heat pump on constantly never turning off when theres a heating demand and trickles low flow temperature heating into the house.

 

Read the manual, all of this info is in there. An adaptive curve may be suitable for a small number of properties where you cannot get things calibrated properly with either full weather compensation (best option) then the second option would be active (weather comp with room influence modulation) .. expanded with an adaptive heat curve is the least desirable option for efficiency... but might work for some houses.

Edited November 15 by Lofty718

[ReedRichards]

14 hours ago, suspicious_squirrel said:

Intelligent octopus Go, 23:30 - 5:30.

Maybe Eon NextDrive 00:00 - 07:00 would work better for you?  It will depend on whether you have solar PV and need the good export rate Octopus gives to its import customers.

[PhilT]

6 hours ago, Lofty718 said:

Adaptive is not the most efficient, when I have it turned on it has the curve higher than I would set it manually and tends to overheat the house

Yes this might happen the first time but that's why it's called "adaptive" - the idea being to leave it for however long it takes (a few days, a week maybe) in a steady state at your chosen room temperature setting, so it can "learn" from the micro-incremental temperature changes how your room temperature reacts to your flow temperature, with reference to your target room temp. If, the first time, the flow temp climbs too fast, the next time it will choose a more gradual increase in the flow temp, and repeat this "learning" until the flow temp behaviour achieves a steady state vs. your room temp target. Then if the sun is shining through your window it will reduce the flow temp further according to the higher rate of room temp increase.

[Lofty718]

3 hours ago, PhilT said:

Yes this might happen the first time but that's why it's called "adaptive" - the idea being to leave it for however long it takes (a few days, a week maybe) in a steady state at your chosen room temperature setting, so it can "learn" from the micro-incremental temperature changes how your room temperature reacts to your flow temperature, with reference to your target room temp. If, the first time, the flow temp climbs too fast, the next time it will choose a more gradual increase in the flow temp, and repeat this "learning" until the flow temp behaviour achieves a steady state vs. your room temp target. Then if the sun is shining through your window it will reduce the flow temp further according to the higher rate of room temp increase.

You are missing the point, heat pumps shouldn't turn off once the heating demand is met because it means when they turn on they will need a higher flow temperature to acheive the desired result which in most cases means a lower COP and the heat pump having to work harder. I don't know any installers that use this setting, only as a last resort to fall back on.

 

I run sensocomfort on my Vaillant boiler and still don't use adaptive, I don't want the boiler and pumps shutting down. I use less gas when on constantly and trickling a small amount of heat into the house. Curve 0.25 for UFH and 0.35 for the radiators

Edited November 15 by Lofty718

[suspicious_squirrel]

Just a quick update:

I dug out the original paperwork, the MCS "customer heat pump proposal pack" has an estimated SCoP of 3.91 at a flow temperature of 45°C (3.65 at 50°C for DHW).
There is a caveat that it could be 30% lower than this, which I beat by 0.163 today! Though I'm also running far lower water temperatures...