@dant 

Good morning Dan,

I suggest that you download the following manual and confirm that it matches your equipment before we proceed any further.

ThermaV owners manual Monobloc

Bad news I'm afraid, my radiators have started to feel warm to the touch. 😥 

@derek-m 

Posted by: @morgan

@derek-m 

 

I knew I had heard that somewhere. 😎 

Hi all

Has anyone adjusted their flow temperature as I hear it can produce decent savings on electricity usage?

Also, how often do others ASHP defrost cycle, particularly at night? 

@hr_3, we dropped ours from 45C to 40C in November. Our previous COP was 2.7 and it’s now over 3, which is good. Depending on how well insulated you are, and if you’ve got UFH or big rads, you could get away with 35C. 

As for defrosts, we’ll easily do 8-10 when temperatures drop. Humid evenings with temperatures in the 1-3C range are worst for us. Sub-zero temperatures don’t lead to as many defrosts for us because there’s typically less moisture in the air.

I asked my installers about switching to weather compensation mode

This was their feedback:

"When we have rads and UFH working together we tend to find using the weather compensation curve is not particularly effective. It can mean that there’s low temperature water in a convective radiator panel which doesn’t provide sufficient output. Our customers with similar set ups are far happier to hit a set flow temp of 50/55 which ensures the panels convect warm air into the rooms.

You can experiment with using the weather compensation mode to see if it suits, but we would recommend just to keep the set flow temperature. Ultimately the thermostat will turn off once it’s hit the set temp so the heat pump will be operating for a shorter period of time at a slightly higher flow temperature and  you’ll find little difference in the ultimate efficiency. You could try adjusting the set back temperature by a few degrees which would mean the temperature in the house is maintained.

Hope that makes sense and do come back to me if there are any further issues re. upstairs heating."

@dant,

I thought on a dual rad/ufh system the ASHP heated water to a single temperature; the rads got fed this directly and the ufh got it mixed with cold water because it didn't need such a high temperature?  Would your supplier still be saying go for a set 50/55 if you didn't have ufh?  A flow temp of 50 is right at the upper end.  

@kev-m The installer (since sacked) who commissioned our rad only installation set flow temps to 55.  I have set it down now to 40 and still the house remains comfortable.

@witchcraft,

I remember seeing an article or video where the installer said they set the radiators at 50C because otherwise the customers complained the heating wasn't working.  

Posted by: @editor

@hr_3, we dropped ours from 45C to 40C in November. Our previous COP was 2.7 and it’s now over 3, which is good. Depending on how well insulated you are, and if you’ve got UFH or big rads, you could get away with 35C. 

As for defrosts, we’ll easily do 8-10 when temperatures drop. Humid evenings with temperatures in the 1-3C range are worst for us. Sub-zero temperatures don’t lead to as many defrosts for us because there’s typically less moisture in the air.

Hi Mars

Thanks, OK I think my ASHP (steibel eltron wpl17) is in line with your cop there (about 2.7)at the moment at 45c flow

I may drop to 35/40c and see outcome.

We have large k2 double convector rads, no ufh but system was installed from scratch, not retrofit so mainly 22mm pipe everywhere. System gets up to 20c no issues which for us is too hot and temperature seems to only drop below 19c after 11-12hours (on the recent colder days at 5c)

@hr_3, give it a bash - you should get a feel for temperature and efficiency within a few days.