Upgrading your current heating system to a high efficiency condensing boiler can save you hundreds of dollars a year. Use the Condensing Boiler Calculator to estimate the cost of upgrading from a traditional to a modulating condensing boiler. How Much Does A Condensing Boiler Cost? On average, homeowners report spending $6,500 to install a condensing boiler that will heat a 2,000 sq.ft. home. This cost estimate includes all materials and professional installation for a 90K BTU condensing boiler with 95% AFUE (boiler efficiency). On the low-end of the price spectrum, a 90K BTU condensing boiler costs $5,680, while the same… Read more »