Posted by: @trebor12345

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@jamespa Can I check something that I done some weeks ago.

My underfloor manifold is set via the 12 flow gauges to a total of 20 l/m.  In the UI of the indoor unit I have reduced the primary pump from 28.5 l/m to 24.3 l/m.

Why did I do this.  I was seeing a lot of mixing in the buffer tank.  Reducing the primary pump flow rate to 24.3 l/m reduced the amount of mixing.  Therefore the return temperature to the heat exchanger is reduced slightly (approx 0.5C). Hope this makes sence.

Yes this makes sense.  Ideally you match flow either side of the buffer, at which point it is pointless (but that is anyway the case).  Since a perfect match isn't possible its better to have slightly more flow in the primary than in the secondary.  This should force the cold water to the bottom of the tank thus (hopefully) reducing the flow temperature loss across the buffer to near zero.

Posted by: @trebor12345

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Nothing really new, except that these Thermo Off periods are way tooooo long at 1hr 20 mins and 2hrs 20 mins. 

Way too long based on what criterion.  From what I recall from your earlier post the house wouldn't cool much in this time.  So why does it matter?

Posted by: @jamespa

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Way too long based on what criterion.  From what I recall from your earlier post the house wouldn't cool much in this time.  So why does it matter?

You always challenge my thinking!  I don't specifically know why I think it's too long.  My only thought is do other systems/users have that long time.

Yesterday it did take some time to get heat into building, the off's didn't help.

It was 0C over night, so when I turned the heating off at 11pm it was 22C, this morning it had dropped to 20.5C in the main living area (20sqm of glass), so a little cool for us.  

Posted by: @trebor12345

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You always challenge my thinking!  I don't specifically know why I think it's too long.  My only thought is do other systems/users have that long time.

Its not so much challenging as seeking to understand.  Your house cools very slowly so provided that the right amount of energy is put in over several hours (which, if the WC curve is correctly adjusted it should), you wont notice it.  It is quite a long off time but that said my heat pump will do that in one of its modes.  My house cools quicker than yours so I do notice it, and therefore dont operate in that mode preferring pure weather compensation instead.

I am reasonably sure that the key to getting this to work is 24x7 operation on WC, with no human intervention other than, not more than once a day and always in the same direction, adjusting the WC settings.  Once thats set up then the various behavioural features of the heat pump and your house can be observed and optimised or adapted if necessary.  Until it is set up you are operating with a (largely human based) control system which is inherently unstable because of the delayed response of your house and the fact that the control system stops working overnight, and is therefore impossible to diagnose.

I find having my thinking challenged is always a good thing 🙂

Posted by: @bontwoody

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I find having my thinking challenged is always a good thing 🙂

I’m always pleasantly surprised when I find out I’ve been thinking in the first place. 😎 

@majordennisbloodnok ‘Sometimes, I sits and thinks, other times, I just sits’. Toodles.

@toodles thinking is existing, or did I miss some thinking here?

@batpred I think I am too! Toodles.

Posted by: @toodles

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@majordennisbloodnok ‘Sometimes, I sits and thinks, other times, I just sits’. Toodles.

"I think therefore I am" - René Descartes

"To be is to do" - Socrates

"To do is to be" - Jean-Paul Sartre

"Do be do be do" - Frank Sinatra

@majordennisbloodnok Tibby or not Tibby - anyone seen my cat?

Posted by: @jamespa

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Yes this makes sense.  Ideally you match flow either side of the buffer, at which point it is pointless (but that is anyway the case).  Since a perfect match isn't possible its better to have slightly more flow in the primary than in the secondary.  This should force the cold water to the bottom of the tank thus (hopefully) reducing the flow temperature loss across the buffer to near zero.

JamesPa.  Thats one thing that I do have right.  Cross that one off the list.

JamesPa Below is the plot of yesterdays run (30 Nov).  Surprise NO THERMO OFFS.  Ran for 10.5 hours.  Im afraid it's a fluke!!! 

I have always expressed the view that the HP is oversized, as you have found the Night/ECO setting, I turned it down to 50%.  This is the result.

It's not a sustainable way to run the heating.  

Does it tell us anything else?

I am looking at setting up the WC.