Noz85

So you are suggesting that my boiler is set at 55C and the mixer 45C?

Thanks, both. I have an IR thermometer for the pizza oven. My dad also has a temperature sensor which is accurate to 1degree so he claims so could try that also. I think you are right, JohnMo. Dropping the flow temp 10degrees was a little bit hasty. Careful trial and error is a more suitable approach. I have taken a meter reading the other week after reducing the flow temp. So I will see what it has used and put it back for comparison, then maybe starting making finer adjustments. So we don't think that the mixer setting matching the flow temp out at the boiler is important?

Thanks for having a look at this .. We have lived in our house for 5 years now and it has UFH heating throughout installed to the developers spec. The ground floor is screed and upstairs is installed between floor joists. Due to the ever-rising cost of our energy bills, I have looked into the potential saving that can be achieved by lowering the flow temperature that leaves the boiler. It has always been set to 55degrees and I have lowered it to 45degrees as suggested by a couple of articles I read online. Unsurprisingly, the house is colder. I anticipated that the system would get the house to the safe comfort level but take a little longer. However, it is a little colder than I expected, and depending on what is going on outside, not quite comfortable enough. The mixer valves on the downstairs and upstairs manifolds are set to 55degrees, as they have always been. I have not yet altered this setting, and this is why I am writing this query on the board. I assume that the mixer valve temp should match the flow temp? Could this 10degree discrepancy between boiler flow temp and mixer valve setting be contributing to the house being particularly cold? Or not really? Do I just need to increase my flow rate back to 55degrees and forget this experiment? Unfortunately, the manifolds do not have temperate gauges for feed and return. So I have no idea what the temperature difference is. My concern is that a lot of the rooms are calling for heat, even though I am only trying to achieve 17/18degrees in most rooms, 19degrees in two. (These temperatures may appear to be low, but when the flow rate was 55degrees the house was a nice temperature). Constant calling means that the boiler is running a lot and therefore I assume this is probably using more gas than having a 55degree flow temp.