I would say nothing more than 40 pounds. i would be happy to do this for you, however if the pipework does want adjusting the entire central heating wil have to be drained down and then re-filled, then you will require an inhibitor to put back into the system to prevent internal corroding, this would be another 25 for the inhibitor. I would be happy to come and have a look for you. Paul Jones/ Plumber tel 01142796589