Hi, just looking to inform myself before escalating issue with either Valliant or plumber. Had extension finished in Dec 2018, new pipes throughout to shower/taps/radiators. New Valliant boiler installed. Water wasn't heating fully from the off, had Valliant out Jan 19, replaced heat exchanger and all fine. Same thing in Jan 20, boiler serviced in Dec 19 and hard water filter replaced. Had Valliant out in Jan 20, replaced heat exchanger as it had scaled over. Had them out again this week as water temp dipped and they had to replace exchanger again. No charge anytime but mentioned there could be if keeps happening. Assuming the filter is doing its job is there any other issue that could be causing this. Do I have grounds for a new boiler? Its the 3rd new exchanger in just over a year in anew boiler. Many thanks for any help.