We can’t fault the quality of the job your guy left, and he was very tidy also, tell him well done! This will depend on how old and inefficient your existing boiler is and the fuel your boiler uses here are some examples of potential savings for a home heated by gas central heating. Boiler problems? talk to frank! If your gas boiler is over years old, it may only be % efficient our package includes %+ efficient gas boiler and upgraded.