Posted by: @jamespa

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@giganto 

Thanks for posting the photos which are very useful.  You are asking the right questions!

Without knowing exactly how the Honeywell is wired/connected its difficult for me to tell how best to disable it.  Can you tell anything from the wiring around?  Others, eg someone with one of the Honeywell devices, may well have a better idea.

The final picture is your weather compensation curve.  This changes the temperature of the water that the heat pump produces to feed the radiators according to the outside temperature. With the current settings its likely you are paying 30% -50% more for your heating than you need to and are less comfortable than you could be.  Dont panic though, it can be changed and we will provide help.

Before you start changing anything I recommend you read this introduction to heat pumps which explains some of the key concepts.  You need to forget everything you learned about running a boiler (much of which was wrong even for boilers!) and think instead 'low and slow' - on 24x7 at a very low level, just enough to keep the house warm.  The weather compensation is key to this.

If you read the introduction and tell us something about how the Honeywell is connected we can talk you through the key steps.  If you do this your house should be more comfortable and your heating bills lower.

 

Thanks for the reply. I have read through  the info and posts again. I am ignoring the Honeywell at the moment. I have activated the AT compensation and moved the curve so to be around 35C  FT @ 0C which ranges from 25C FT @  20C  to 50C FT @ -30C  (40C FT @ -10C). I'll try this for a few days to see. I've attached pics. I think that I was looking for 'unicorn dust'. I just spiked the DHW for a shower!

Posted by: @giganto

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. I think that I was looking for 'unicorn dust'.

Not if you are systematic and patient.

The high OAT end is logically something like 20 at 20, or more practically something like 25-27 @ 16 or thereabouts.  At this level it's fairly self regulating.  So that leaves only the low oat end.  Start at the design ft if there is one or if not 35 for ufh or 45 for rads at design oat (or do a linear extrapolation of that to a lower oat if you wish  Then turn it up ir down as appropriate, once a day no more frequently.   Once the house is getting close to the right temperature (go by feel) start trimming radiator lsvs if there are major discrepancies.  

Fortunately rad balancing doesn't have to be particularly accurate because rooms share heat.  Adjusting the WC curve is basically one parameter up or down, same as a thermostat.  

This really is much more difficult to describe than to do, so long as you are patient.

Posted by: @jamespa

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Posted by: @giganto

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. I think that I was looking for 'unicorn dust'.

Not if you are systematic and patient.

The high OAT end is logically something like 20 at 20, or more practically something like 25-27 @ 16 or thereabouts.  At this level it's fairly self regulating.  So that leaves only the low oat end.  Start at the design ft if there is one or if not 35 for ufh or 45 for rads at design oat (or do a linear extrapolation of that to a lower oat if you wish  Then turn it up ir down as appropriate, once a day no more frequently.   Once the house is getting close to the right temperature (go by feel) start trimming radiator lsvs if there are major discrepancies.  

Fortunately rad balancing doesn't have to be particularly accurate because rooms share heat.  Adjusting the WC curve is basically one parameter up or down, same as a thermostat.  

This really is much more difficult to describe than to do, so long as you are patient.

AT curve centred around 35C as per last post. Late evening not quite enough comfort for the missus, so I altered AT curve to 37C. At approx 4 ish am, both of us downstairs - synchronised loo system - complaining how warm it was so I quickly altered AT curve back to 35C - fabulous this morning when we got up properly. Anyways I attach some pics of the temp traces of the system showing the Flow and Return (oulet and Inlet) temps. You can clearly see the lines around 4 ish pre alteration, then a little reset downwards? then settle at reduced values. i checked again when I got up and noticed another slightly larger reset? before returning to the previous temps. With the second blip, you can see the Flow and return temps appear to separate to about 5C apart (Usually around 2.5 max) before returning to normal readings. I thought that it might be something to do with defrost but with the larger dip the AT(outside) actually rise upwards at the same time. Any thoughts?

would be appreciated

The last photo is defrost for sure (or cooling, but presumably not at this time of year).  You can tell because flow < return.Once you get close to the right curve I would go for one adjustment every 2 days or even longer, and make smaller changes.  Houses take a very long time to stabilise so adjusting too much too frequently just leads to oscilllation.