Prices shown are valid on 2018-05-25. The costs for replacing a boiler will vary, but a straightforward oil boiler replacement plus thermostatic radiator values will typically cost about £3,000. This is my first yelp review ever glad i read steve k's review and called jim. Corrosion within central heating systems accounts for 90% of all system/boiler failures if you have any of the following problems your system will benefit from flush cleaning. Ground movement causing derby drain problems.