Air source heat pump , heating mode

[saveasteading]

Can someone explain the following please, from a Vaillant specification?

 

Is there an optional setting for 35/45/55 C? or does it change automatically as necessary?

 

from the A+++ to A++ variation I assume that the system works better at the lower temperature, but can be increased  to suit circumstances.

I expect there is a big difference in running cost between A+++ and A++.

SCOP of up to 5.03  sounds good but "up to" makes it  a bit meaningless.

 

And what is that 'F' about? 

 

Energy efficiency class 35°C	(A+++ to F)	A+++
Energy efficiency class 55°C	(A+++ to F)	A++

 

https://www.vaillant.co.uk/specifiers/products/arotherm-plus-heat-pump-74048.html

[billt]

I would guess that you either choose the flow temperature for a constant temperature or there is an optional control system thaht uses either weather compensation or load measurement to adjust the flow temperature. I'd guess the F is for HW heating with a high flow temperature.

 

If you scroll down on the page you linked to there is a more detailed spec to look at (although it's not detailed enough).

There's an interesting BRE page which will estimate annual efficiency of a heat pump system. .https://www.bregroup.com/heatpumpefficiency/index.jsp

 

It lets you select the heat pump, flow temp etc and shows a graph of the estimated COP.

 

 

[IanR]

3 hours ago, saveasteading said:

Is there an optional setting for 35/45/55 C? or does it change automatically as necessary?

 

You need to work out the flow temp your emitters require to deliver the heat in to the house to offset the energy losses.

 

You then set the Flow Temp on the ASHP space heating to match this.

 

The larger the emitters, and lower overall heat loss, the lower the required Flow Temp and better SCOP.

 

From this set Flow Temp, you can then use a weather compensation curve to increase the Flow Temp as the outside temp drops. This allows a lower general Flow Temp, and even better SCOP, raising it only when needed. I found it better to run without weather compensation at the start to understand how the house reacted to a known Flow Temp, and then set up Weather compensation.