I was looking to replace my very reliable, but over-40-year-old Gloworm heat-only boiler. I wanted a boiler that had a stainless steel heat exchanger, as I believe that is the best variant available. I looked at Worcester Bosch but rejected that along with many others. The only one that suited my requirements was the Viessmann 100-w B1GA heat-only boiler with a condensate pump, as my boiler is on an inside wall. The installation was difficult to start with, as the microchip shortage delayed the supply, but one was found a hundred miles away or so and was brought here by the fitters Snug Energy Doncaster. The installation was carried out in one day successfully with little disruption. As of today about 6 months since installation, the system is working just as it used to do with my original boiler. The Viessmann is just as quiet and efficiency should be improved. There are 3 other Viessmann boilers in the family, and all seem to have been reliable for their owners. Recommended is all I can say.