Which? magazine has rated 370 boiler brands including worcester bosch, viessman, baxi and vaillant and found prices can range from £600 to more than £2,400. If your home heating system is past its prime and your energy bills go through the roof, you may be wondering how much does it cost to install a new boiler? First, the problem needs to be isolated once it is, the unit needs to be replaced. Building regulations state that.