Posted by: @trebor12345

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Internal Temp: 22C
Curve: 0.2

You won't be able to achieve those simultaneously unless curve 0.2 happens to be exactly the correct curve for your house.  To find the correct curve set target temp to 22 (as that is your target temperature/ and adjust curve factor slowly (no more than 0.05 per 24 hrs) until house settles at 22.   Best done a bit later in the season when demand is higher, at this time of the year there is still lots of noise on demand.

Posted by: @trebor12345

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Manual setting
24 hrs run time

Settings correct for that yes.

Posted by: @trebor12345

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Secondly.  My flow temperature is a lot higher than the target being set by the Heating Curve.  Its 17C outside at the moment so I should see a flow temp of 25C according to the curve, but the app, sensocomfort, and my temperature probes are seeing 27

Your pump is cycling at low demand so ft will be higher much of the time.  Also I think there is an installer setting for mine ft (in the hpui possibly) which may override.  I wouldn't get too concerned at this stage in the season.

Posted by: @trebor12345

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Some addition data that may be relevant:  Typical power 400 watts consumption, compressor running at 25%. HP is cycling every 2hours (which is to be expected).

That's a good figure, is it the 5kW pump? My 7kW bottoms out at 600W.

Posted by: @jamespa

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Posted by: @trebor12345

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Internal Temp: 22C
Curve: 0.2

You won't be able to achieve those simultaneously unless curve 0.2 happens to be exactly the correct curve for your house.  To find the correct curve set target temp to 22 (as that is your target temperature/ and adjust curve factor slowly (no more than 0.05 per 24 hrs) until house settles at 22.   Best done a bit later in the season when demand is higher, at this time of the year there is still lots of noise on demand.

That's a good figure, is it the 5kW pump? My 7kW bottoms out at 600W.

I am still trying to get to grips with how the Curves and set temperatures inter act with each other.  I set 20C as the base-line for all the Curves (as thats what is shown in the manual/chart.)  I was of the understanding if I increase the setting of 20C to 22C then that would give me a higher Curve, resulting in a higher flow temperature.  Have I got it right?

The 400 watts is on my 3.5 Kw HP.  I am really happy with the low running.  I suspect the 25% modulation is the lowest it goes.

Posted by: @trebor12345

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I am still trying to get to grips with how the Curves and set temperatures inter act with each other.  I set 20C as the base-line for all the Curves (as thats what is shown in the manual/chart.)  I was of the understanding if I increase the setting of 20C to 22C then that would give me a higher Curve, resulting in a higher flow temperature.  Have I got it right?

Yes to the final sentence.  There are actually two controls that do more or less the same thing if you operate on pure wc, namely the set temperature and the curve slope/index ( 0.2).  Both shift the curve albeit in different ways.  

However their effect differs if you operate other than in pure WC.  In that case changing the set temperature, as well as shifting the curve, changes what the system does in response to the temperature sensor.

The best way to set it up is set the target to the value you want, then adjust the curve until that value is achieved. This calibrates the curve to your house. 

After that, if you want to change the target or program a set back just do so leaving the curve where it is.  But as I say above change the curve slowly and refine the settings when it's cold.

Alternatively many say active mode works well.  This does an element of auto adjustment of the curve provided it's in the right ballpark.  You could just set the temp you want, enable active mode and (preferably) report back!

Posted by: @trebor12345

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I have my hot water temp set to 42 and had to reduce hysteresis (an option on the installer menu) to 3. Now the water is warmed (during set time periods) whenever the sensor reads 39 or below. 

I too had to reduce the hysteresis even though my dhw temp is set to 48.  Occasionally with a reheat programmed once per day, it would be just hot enough not to trigger reheat on day 1, but too cold to be acceptable by day 2.

Posted by: @jamespa

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I too had to reduce the hysteresis even though my dhw temp is set to 48.  

I too found the same thing, so reduced the hysteresis.  Works like a dream now!  The Legionnaires cycle is still a little problem in that the water is too hot.

@trebor12345 

I have been meaning to get home assistant to tweak the legionaries cycle for once a month, at the moment it is also weekly…

Still trying to understand my new Vaillant aroTHERM heat pump (3.5kw). To recap a 2024 built bungalow with a very low heat requirement of just 12 w/m2.  Therefore the heat pump is cycling with an off time every 60 minutes (consistently), so average of 12 cycles per day (see attached). I do not believe this to be a major problem for the heat pump in the shoulder months, but according to AI, the overall system performance/reliability could be improved by increasing “Compressor start-off threshold” from 60 minutes to 100 or 120 minutes.

Notes: Operating pure WC. Compressor runs at 25%.  Curve temperature set of 25C, HP produces 26.3C. (HP unable to disperse the heat generated).

Does making this setting change sound a sensible approach?

@trebor12345 

That curve looks healthy to me.  I wouldn't change anything at this stage and certainly not because AI BS tells you to.

Heat pump has to cycle when demand is less than min outtput. Once per hour is not bad

Posted by: @jamespa

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@trebor12345 

That curve looks healthy to me.  I wouldn't change anything at this stage and certainly not because AI BS tells you to.

Heat pump has to cycle when demand is less than min outtput. Once per hour is not bad

JamesPa

Thank you.

Just need to check my understanding on something.  I am running pure weather compensation so Inactive mode.  In this mode the target flow temperature is calculated using the outside temperature and heating curve selected, in my case 0.2  Setting a Desired Room Temperature on the sensoComfort Controller has NO effect? (You can set the Desired Room Temperature to 30C and it will have no effect on the flow temperature)

Posted by: @trebor12345

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Setting a Desired Room Temperature on the sensoComfort Controller has NO effect? (You can set the Desired Room Temperature to 30C and it will have no effect on the flow temperature)

That is not the case.  The heating curve adjustment sets the shape of the curve but the set desired temperature (if set to anything other than  20C) offsets the curve.  This is explained on page 4 of the manual here

One way to think about this is that the heating curve adjustment adjusts the heating curve to suit the characteristics of your house, whereas the set temperature adjustment adjusts it according to what temperature you want to achieve inside your house.  

Although initially confusing its actually very sensible, once the heating curve is approximately right and achieves 20C when the system is operated 24x7, just adjust the set temperature until you feel comfortable, as you would a thermostat.  This approach means that setbacks and set-forwards work in  the most efficient way possible and if people want a different temperature they can tweak the set temperature without having to get into the complexities of the WC curve, yet maintaining optimum efficiency. 

Vaillant are not unique is dealing with weather compensation this way, its common to several EU based boiler manufacturers which have had to deal with mandatory weather compensation in boilers for a couple of decades.  The asian heat pump manufacturers have not historically had to face this regulation so their UI is less sophisticated.