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[Alwayslearning22]

Should I run my a2w heat pump on a fixed temp of 45? Or would a weather comp curve be better?

I would like cheap bills and a warm house? If that’s possible.

[ProDave]

More information?  like how is the heat delivered? Under floor heating or radiators for example?

[JohnMo]

In general WC allows the lowest supply temp, as heat loss equal to heat supply.  Needs a mind set change as heating is on 24/7, limited use of thermostats 

[Alwayslearning22]

2 hours ago, ProDave said:

More information?  like how is the heat delivered? Under floor heating or radiators for example?

It’s. 3 story new build with radiators  and a 4kw split heat pump.
 

[ProDave]

As replies above, WC in theory should reduce bills a little as the lower temperature the heat pump can operate, the higher will be the COP.  but it willmean the heat pump will be running for longer or even 24/7.

 

It would be interesting from one of the people that has implemented it, if anyone has been able to quantify the sort of savings they have observed compared to constant temperature.

[JamesPa]

The thread here has a discussion and a model of WC; (scroll down for v2 improved version).

 

Of course model and actual may differ, but order of magnitude I would think this is likely not bad.  No allowance is made for pump consumption but, knowing your heat demand and pump power, would enable a rough calculation to be done.  Some people have contributed measurements also.

 

[ReedRichards]

3 hours ago, JohnMo said:

In general WC allows the lowest supply temp, as heat loss equal to heat supply.  Needs a mind set change as heating is on 24/7, limited use of thermostats 

 @JohnMo always says this and I always respond that neither 24/7 operation nor limited use of thermostats is a prerequisite of Weather Compensation.  If you want to take WC to the limit of peak efficiency then, probably, yes.  But I don't have 24/7 operation and I use two zones with two thermostats and I'm still sure that WC saves me money over using a fixed water temperature.    

[Alwayslearning22]

Thanks for the replies. Some of that stuff is very complicated for an idiot like me. 
Is it ok to run radiators on weather comp? I had a heating engineer out recently and he said weather comp is only for underfloor heating. 
I should run it at a fixed flow of 45 with it turning off and on. 

[ReedRichards]

I have only radiators and I run them with Weather Compensation; it works fine.  Since radiators generally require hotter water in cold outdoor temperatures than you use for UFH, then you probably derive more cost benefit from using WC with radiators than you do with UFH.  

[Alwayslearning22]

2 minutes ago, ReedRichards said:

I have only radiators and I run them with Weather Compensation; it works fine.  Since radiators generally require hotter water in cold outdoor temperatures than you use for UFH, then you probably derive more cost benefit from using WC with radiators than you do with UFH.  

Thanks for the reply. 
I actually prefer the constant heat in the house with WC. 
I sometimes think certain heating engineers know less than let on about these systems. 

[JamesPa]

2 hours ago, ReedRichards said:

.  Since radiators generally require hotter water in cold outdoor temperatures than you use for UFH, then you probably derive more cost benefit from using WC with radiators than you do with UFH.  

According to my model that's spot on.  At a flow temp of 35C, typical of ufh, the saving due to WC is 5%.  At 45C it's more like 15-20%.

[JohnMo]

3 hours ago, Alwayslearning22 said:

think certain heating engineers know less than let on about these systems

I think quite a few have zero idea