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Posted by HeatPro on January 04, 2005 at 07:15:47:
In Reply to: Should I replace my boiler or repipe it? posted by Dave on January 04, 2005 at 05:03:57:
Your problem is due to the different history of two continents. You Lochinvar boiler is more like European boilers like Bosch, etc, that use smaller tubes, rather than large heavy vessels of water. If it were a problem of Lochinvar design, then Europe and Britain would not have boilers any longer. The small-tube design permits high efficiencies and the instant water heater craze is a result of that design.
Problems occur when the installer-designer of a hot water system can not 'catch on' to the need to use a variety of designs that apply to the custom situation that is hot water heating. If your installer can understand loop-subloop design, where all the water for the whole house can pass through the boiler, instead of the 'spider' multi-zone system used by the large-mass vessel where water is reduced when few zones open, you are on your way to few problems. The 'buffer' tank is a way to get more water to flow through the boiler so it doesn't short-cycle; in effect, it turns the small-tube boiler into the old large-mass boiler the installer can deal with from past experience.
As as some indirect water heater tanks are made to accept boiler water on the tank side and domestic water is made in them py passing through copper coils in the water, that would make an excellent 'buffer tank.' Tanks that cost several thousand dollars are usually ASME rated pressure tanks; but you don't need that sever duty, just a tank that can take the pressure of boiler water, which indirects can.
So you have a choice to repipe to a loop-subloop piping arrangement, add a buffer tank to bypass its water through the boiler to compensate for indadequate flow when closing zones off, or get a new large-mass boiler that any old-timer USA installer understands. Your choice.