franpipeman wrote:I guess that if you have a more than one zone system you need to set your feed rate up to the largest btu consuming zone.That would make the smaller btu zones , when operating. less efficient yes? When the weather is cold ones needs to burn more fuel.
If you have a small zone call for heat, the boiler will simply run until it reaches the high limit and then shut off...assuming you have the controls setup that way. If nothing else calls for heat for several hours, the heat stored in the boiler will be lost to the surrounding area and to the chimney. In my case, the boiler keeps the basement comfortable and the heat going up the chimney maintains a good draft...so I don't worry about it.
When you have multiple zones of varying size, the a control that adjusts the boiler temperature based on load becomes beneficial. Constant/frequent circulation is also nice with a high-mass system.