Hi I am a newbie and hate to join and ask for help straight away. I am having issues with my wet underfloor heating using serious oil, 900 litres in 45 days gone, i have it on 8 hours but have also run it on all the time but it doesn’t matter what I do i uses a lot of oil. upstairs radiators barely on once a week maybe and an hour of hot water each day. I could write a book on it but will keep it as brief as I can. Its a hep2o system with two manifolds a 12 port and a 6 port controlled by two micro center controllers, 12-8 and 12-4. Run by a Warmflow 150/170 boiler. The problems started a few years back when one of the controllers Micro centre 12-8 stopped working the relay for heat demand was permanent on.. I got it replaced however I believe the electrician mixed up the wiring for the actuators as some of the stats are not working the correct zone, which I can work out myself hopefully. However both separate flow manifolds do not run equal temp? Regardless of the valve setting 1-5 on the end of the flow manifold, The 8 port is 45 degrees the 12 port is 55 degrees. Why would this be? Both are fead straight from the boiler? Also what purpose do the valves on the end of each flow manifold serve? They link a pipe into the return side? Is this to recirculate the return? Also recently the actuators on the 8 port manifold have stopped opening when the heating turns on , they only open if you go to a stat in that zone and go from full demand to zero and back why is this? They work fine then for the full 8 hours until the next time the heating turns on they do the same fault. Should a mix valve not have been installed in the system? As rads run 80 degrees and ufh 40 to 60?? I have my boiler at 60 which is the lowest it goes for the ufh which is high to me, its a big boiler too warmflow 150 I believe it is too big for what we using it for mainly the ufh. Can a different jet be installed to reduce oil consumption and temperature? I think the install has been a bodge the house was only built in 2008 and it has been a very troublesome system with high running costs. I am an mechanical engineer by trade but definitely not an expert when it comes to UFH so treat me kindly and thanks for any help or advice. I can attach photos of the system when I get home!