how much for a new combination boiler
1 If you are keeping the same type of boiler (e.g. if you have a existing combi boiler you are replacing it with a new combi), the price to buy and install it will start at about Â£1300 provided there are no real plumbing adjustments required.pproximate starting prices are discussed below: 1  If you are keeping the same type of boiler (e.g. if you have a existing combi boiler you are replacing it with a new combi), the price to buy and install it will start at about Â£1300 provided there are no real plumbing adjustments required.