Range from the cheapest fitting of a boiler magnetic filter £40 (APG Assist Plumbing & Gas based in W5) to the dearest fitting of a boiler magnetic filter £170 (ThePlumbers.org based in TW7).
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 Kew by posting a job with HaMuch and we will send it to heating engineers in Kew.