Boiler Installation Cost Guide

We deliberately do not publish boiler prices. Any figure on a website is either an unrealistically low headline or a padded average, and neither helps you budget. What we can do is be completely transparent about what moves the number.

The main variables are: the boiler brand and output you choose; whether it is a like-for-like swap, a relocation or a conversion; the condition of your existing system and whether it needs a power flush; gas supply pipe sizing, which frequently needs upgrading in older Kingston upon Thames properties; the flue route and any scaffolding or access requirement; the condensate route; and controls, from a basic programmer to full smart zoning.

Secondary factors include removing loft tanks and a cylinder, making good after a back boiler, magnetic filters and scale reducers for hard water, and whether the work is in an occupied property needing phased hot water.

The practical route is a short survey — often the photos and answers you can send us are enough for an accurate figure. You then get a fixed written price that does not move unless you change the specification.