I have a older 5 bed brick house (Edwardian Terrace) with a new ecodan ASHP heatpump installation. We run it 18+ hours in the day with a flow rate no greater than 45 C. We have c. 10 radiators.
I have reading the voltage from the Sika Vortex (Heat flow sensor for ASHP) and I am getting a flow rate of acboutr 12 l/min. When calcualting the temprature difference and the power output, I get a reasonable COP of 3 ish. This suggests that the flow rate is correct.
How can the flow rate be so slow? I have two circulation pumps comsuming 50W, so there is not an abscence of pressure. One of the pumps is a Grundfos ALPHA3 which shows a head of 6m.
The radiators on the ground floor that are furthers from the 22mm pipes comming down have their lock shield valves fully open and just do not seem to be getting enough flow.
What to do?
Replacing any of the pipework on the ground floor is a major excercise as we have hard floorings everywhere.