Underfloor heating not getting hot enough

[Vicdiy]

Assuming the UFH TMV is working correctly it still requires ~ 10C/15C differential to operate properly so possibly the LLH secondary flow is excessively higher than the primary flow which means the UFH return will just short circuit the excess to the flow side.

Good point. My daughter rang me yesterday and said that following the latest visit from the boiler installer to tidy up some electrics the UFH was now working perfectly. Unfortunately she wasn’t there at the time but is texting him to see if he had done anything to the UFH circuit as he had previously said he didn’t know why it wasn’t hot enough. I will post if I find anything out. Thanks for your advice.