Posted by Harold Kestenholz - Hydronic Network on August 02, 2001 at 13:13:46:
In Reply to: Re: Need advice on Laars Endurance gas boiler(formerly Trianco Heatmaker) posted by Paul from NH on August 02, 2001 at 12:06:28:
Yes, the water flow through the boiler must be established before firing the burner. If many small zones will open and close, changing the rate of flow through the boiler, the boiler should have a bypass to insure a set minimum of flow through the boiler so it will not flash to steam and damage the tubes.
If the sytem is very old with standing cast iron radiators, the circulator can be left running all the time. The thermostat can then turn the burner on when the room temperature drops. A house with baseboard radiation can have the same if the loops have no zone valves. Don't worry about the circulator running cost, they are 1/8 horsepower or less and draw the energy of a light bulb - they last longer running all the time without starting and stopping loads.