Hello,
I am the owner of the ‘Brighton & Hove’ ecodan system! Over the past year or so I have made some really significant changes to the original installation to get it working correctly.
The actual COP for the CH is around 5.5. We still have a little air in the system which is causing a drop in the measured efficiency in the DHW cycle as air appears when the flow temp hits 45C.
What have we done to getting the CH working so well?
i) I have upgraded all the pipework from what was originally installed. The primary pipework runs are now in mainly 28mm with a little remaining in 22mm. We have a large Emmetti manifold that distributes water directly to each radiator uisng 16mm MLCP pipe. There are no TRVs.
ii) there is a single large Grundfos MAGNA pump. Our flow rate is typically 1440l/h. That is 24 l/min. There is a section of 22mm pipe remaining and I expect we will see it increase further once that is shorted and replaced in 28mm.
iii) we only ever turn off two radiators in the loft extension (office) at the weekend. We have no other radiator controls. Each radiator gets a measured 4l/min from the manifold.
iv) the heating controls are a combination of loxone/knx. In reality is is very simple config. We have a precise digital thermometer in each room. When any room ‘calls for heat’ the system comes on and heats every room in the house. The system has a minium run time of 1 hour. It currently runs at a manually set 32C.
v) as the temperature drops as it cools the system will remain running all day. At that point we will increase the flow temp. I am hopeful we will not need to push it beyond 40C. This is estimated and hopeful, rather than being scientifically calcuated.
vi) radiators are typically long K3 ones. It seems to be that there is only one room (the kitchen) that is causing the heat to come one. I think that this due to poor insulation/drafts and an undersized aluminium radiator that was originally used with a gas boiler. I am considering replacing the rad with a floor standing 1600x300 K3.
I have found the width of a radiator to be the most critical factor, and the height is not needed. A thermal camera image of our 900x900 radiator shows the bottom half doing very little.
I convinced that TRVs are bad for a ASHP installation. They throttle the flow by partially closing when a room is at temperature. ASHP is much more suitable to a ON/OFF arrangement. And then using the precence of an ON to start up the system; then we give every room heat while the system is running.
Currently the system comes on when a single room wants heat. I could change it so that it requires two rooms demand heat before the system starts up.
Let me know if you need more, or pictures.
Incidentally we use every rooom in the house each day (other than the office being unused at weekends), and the house is always occupied.
George