If you want to know more about the different types of boiler, go to. E independence blvd, suite o. Fired boiler / hrsg, sizes up to 1000hp. To use this feature you must be signed-in to your account, please. No more intrusive, pushy sales visits at home. In general boilers are on all the time, so that you have warm water day and night with the help of a timer, you decide when the water is to be heated, for instance.