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Water law settings... A year on

 
Air Source Heat Pumps (ASHPs)
Last Post by Profzarkov 4 weeks ago
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Profzarkov
 Profzarkov
(@profzarkov)
Trusted Member Member
Joined: 2 years ago
Posts: 65
Topic starter 10/04/2026 4:15 pm   [#2943]

Hi

I've had my system for well over a year now and I'm very happy. The Samsung ASHP plus 5.2kW solar & the Powerwall 3 are all doing very well.

I've been reviewing my water law settings & would appreciate any comments.

The dhw temp is now 46°

Quiet mode is on 2400-0730, although I can't find any info on what this actually does. I know - makes it quieter! It's next to our bedroom and is pretty quiet anyway.

201   15° & -2°

202  31° & 44°

 

I still use my Hive thermostat, mainly to monitor the house temperature & graphs.

I have it set to 19° daytime & 18° overnight.

I know I should scrap or at least raise the thermostat up high. What values would then be needed in the water law...

 

Cheers 

Steve



   
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JamesPa
 JamesPa
(@jamespa)
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Posts: 4909
10/04/2026 4:25 pm  

Posted by: @profzarkov
↑

I know I should scrap or at least raise the thermostat up high. What values would then be needed in the water law...

That depends on your house.  The only way to find out is to turn hive and any TRVs up high, then turn down/up the low OAT WL setting until the house is just at the right temperature.  You cant really do this now until next season!  You need to do it slowly, ~one degree per day.

I would probably adjust 31 to perhaps 27 or even 25 and 15 to perhaps 8/20.  Logically its 20 at 20 or perhaps 20@17/18 (ie when the OAT is the same as the desired room temp you need no heating) depending on the OAT at which your house in practice reaches the desire IAT with no heating.  This isnt that critical though. 

I would also adjust -2 to something lower, perhaps -5/-10.  The reason for this is you want the FT to keep rising if the OAT falls below design temp.  With it set as you propose it will flatline when the OAT reaches -2.  

Hope that makes sense.


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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Profzarkov
 Profzarkov
(@profzarkov)
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Posts: 65
Topic starter 10/04/2026 4:35 pm  

Yes it does

Apart from the abbreviations!

We're in West Wales and so temps never go below zero.... usually!

I'll have a play.

Many thanks 

 



   
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Profzarkov
 Profzarkov
(@profzarkov)
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Joined: 2 years ago
Posts: 65
Topic starter 29/04/2026 10:40 am  

@jamespa 

I've adjusted a few parameters 

201 is now 16°.     -4°

202 is now 27°.    43°

If that makes sense.

See what happens next winter.



   
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