BEJB

Yes, I followed the instructions as carefully as I could. I've attached a photo below. The Heatmiser is still in place, but is entirely disconnected and turned off. I'll get rid of it when I am absolutely 100% sure I'm not going to go back to it! When I do that, I'll arrange the power feed to the Salus units more neatly. The only bit where I improvised regarding the Salus was to cable tie some foam lagging around each of the thermistors. This was just to make 100% that they were at the temperatire of the pipe and were not influenced by other hot things around them. It seemed fairly sensible.

Yes, the heating system has three pumps, primary and one per zone. There are no valves in the heating circuits. The system also provides DHW in a tank. So there is another pump for that and the three position valve selects whether to send the heat to the DHW heat exchanger or heating. It can't go to both at the same time - hot water takes priority.

Many thanks for replying so quickly. The later portions of the charts are where zone 1 cuts in and takes all the heat. If I could get zone 2 to behave like that and heat the kitchen, I would be happy! I'm not sure if I have anything as grand as an install schematic. However, it is a standard Ecodan pre-plumbed FTC5 cylinder, so I have attached a couple of diagrams that show that. In the first one, number 22 shows the low loss header, with the two spare ports for zone 2. The second diagram shows zone 1 and zone 2, with the pumps associated with those zones. Does that help understand the configuration? Thanks again Eric

A couple of years ago, I bought a house heated by a 14kw Ecodan ASHP with a Mitsubishi pre-plumbed cylinder system, that was installed in 2015. It has zone 1 to heat 10 radiators and zone 2 to heat 3 loop wet UFH for the kitchen and utility - also heats DHW. During the colder winter months and late frosts this year, it was clear that the UFH was failing to heat the kitchen/utility floor. The input to zone 1 is physically higher on the low loss header, so if both zone 1 and zone 2 are on at the same time, zone 1 takes the heat, and no heat travels down the low loss header to zone 2. If just zone 2 is on, some heat goes into the zone 2, but much of it travels down the low loss header to the return. This causes the return to be almost as hot as the flow, so the Melcloud reports show the return temperature tracking the flow temperature. When it reaches the peak temperature, it cuts out and flushes with cold water from zone 1. This shows as a sawtooth effect of fast cycling - the cycling is very regular, every 10 minutes. If zone 1 is on by itself, this does not happen - the return remains lower than the flow and there is no cycling (I've attached a melcloud report showing this). The system has been serviced, I've flushed the UFH loops out (via hose - a small amount of muck came out but not much and the flow was OK) and inserted more biocide. I've tried altering the pump speeds. To reduce any flow obstructions, I've removed the flow meters and used blanking plates. I've replaced the Heatmiser UH2 with a standard Ecodan wireless thermostat, and Salus THB23030 actuators. I still have the 10 minute cycling. I have a feeling that the ASHP is too big for the UFH by itself - but not big enough to heat both zone 1 and zone 2 together. I've tried asking UFH and ASHP installers and maintainers, but they look even more baffled than I do and offer no help (with all the green deal stuff, they are too busy installing new systems to bother with maintaining existing ones). I just wondered if anyone had any thoughts or ideas as to anything I could try? Many thanks Eric

Sorted it out. I found that zone 2 would fire up if both the wired and wireless thermostats called for heat. So I disconnected the wired Heatmiser UF2 and set the SW3-1 dip switch in the FTC5 back to the default (OFF - Zone2 operation stop at thermostat short) from ON - Zone2 operation stop at thermostat open. That seems to work as I wanted it now. Many thanks

A couple of years ago, we bought a house with a 14kw Ecodan ashp. Zone 1 is radiators. Zone 2 is a three loop ufh, for the kitchen/utility. The ufh is controlled by a wired Heatmiser 2. I want to replace the HM2 with an Ecodan wireless controller. I have bought one, paired is and configured it as a sensor for zone 2. It shows on Melcloud. I have turned off the HM2. But the wireless controller does not operate as a thermostat. If I wind it up, the ashp doesn't fire up to heat zone 2. I guess the FTC5 is somehow configured to choose the HM2 rather than the wireless controller as thermostat. I wondered if anyone had any idea what else I need to do to get the wireless controller to work with zone 2? What am I missing?