I currently have wet underfloor heating in a large conservatory. When it is cold outside like 2-4c, the temperature in the conservatory will not go any higher than 16c, even with the room stat set a 21c. I have got the UFH pump on the no.3 setting with the mixing valve on 50c. The question is would it be safe to turn the mixing valve up to 55c with a screed floor and ceramic tiles. Would appreciate any comments from any UFH experts.