Range from the cheapest fitting of a boiler magnetic filter £50 (Nat gas based in BR3) to the dearest fitting of a boiler magnetic filter £170 (1977 - Denham Plumbing and Gas based in SE26).
Comparing heating engineers estimates for fitting a magnetic filter gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to connect a magnetic filter in SE20 by posting a job with HaMuch and we will send it to heating engineers in SE20.