Cedric Bainbridge

Hi cb1965, I'm guessing that as your post was nearly four years ago, you will be able to help. I installed the same Heatmiser UH8 UFH system in my current property but used a specialist supplier to install the Mitsubishi Ecodan ASHP under the government grant scheme. I soon started getting L9 (insufficient flow) errors on the Ecodan and on checking, the ASHP engineer had completely ignored the Heatmiser controller - nothing was connected to the heat call terminal block. So, if one of the UFH zones called for heat, nothing would happen unless the Ecodan was also calling for heat, and if the other way around, ie. the Ecodan called for heat but no UFH zones were calling for heat, the Ecodan would shut down with an L9 error. When questioned, the ASHP company told me that was the only way that they could install it and the Heatmiser controller was my problem! I now run the system with the Ecodan remote adjacent to the hall UFH thermostat and keep those set at the same temperature, but I also keep another UFH zone (the coldest zone in the house) permanently open (by leaving that zone's actuator off the valve). This has been okay as a workaround. Now, I am renovating a new property to move into and I have installed the same Heatmiser UFH system, and I am again using the same firm of installers for the Mitsubishi Ecodan under the government grant scheme. However, this time, I want the Heat call from the Heatmiser to control when Ecodan calls for heat. I am happy that they will connect the UFH pump and valves to the Ecodan FTC but I do want the Heatmiser controller to determine when heat is called for and not the thermostat that is built into the Ecodan remote. I can see the terminal block TBI.1 on the Ecodan FTC on my current system which is for 'Room thermostat 1' and nothing is wired into it (nor is anything wired into TBI.2 which is for 'Room thermostat 1'. The wiring diagram lists terminals 7 and 8 for Room stat 1. The Heatmiser terminal block for heat enable has Ls and Lr terminals. Do you know which connects to which? If you have any advice it would be much appreciated. Many thanks.